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Rationale and Objectives: The purpose of this study was to compare the efficacy of the color scale with regard to focal detection with computed tomography in acute ischemic stroke., Materials and Methods: Computed tomography images of the brain of 19 patients diagnosed with acute stroke, based on magnetic resonance diffusion-weighted images obtained within an onset of 24 hours, and the images of five normal patients were displayed in each color look-up table on a monitor. The detection of acute stroke was compared among 15 radiologists. The images were compared in the gray, green, yellow, red, and blue scales of the look-up tables. The observers recorded acute ischemic stroke as "present" or "absent." They also located the position of the stroke lesion and described the degree of their conviction as to whether a lesion existed. Detection was evaluated by receiver operating characteristic analysis. The area under the receiver operating characteristic curves was compared. In addition, reduced fatigue and the ease in image observation were compared., Results: Compared to the other scales, the yellow scale had a significantly higher area under the receiver operating characteristic curve, which indicated that this scale allowed better detection of acute ischemic stroke. The gray scale produced the least fatigue in image observation., Conclusions: The detection of acute ischemic stroke is improved by changing the display monitor from the gray scale to the yellow scale. From the perspective of color psychology, yellow is associated with higher arousal, cheerfulness, confidence, creativity, and excitement. Therefore, the yellow scale may be suitable for a medical imaging display., (Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Purpose: Dual-energy computed tomography (DECT) can be used for visual determination of iodine distribution in the myocardium (iodine image); however, the accuracy and reproducibility of the process remains debatable. Because of the low contrast-to-noise ratio of CT, we hypothesized that quantitative measurement may be more accurate for detecting myocardial ischemia. In this study, we evaluated our quantitative method by comparing it with visual analysis using Tc-tetrofosmin (TF) stress-rest single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) as the reference standard., Materials and Methods: Forty-three patients who had a significant stenosis on cardiac rest DECT and had received Tc-TF stress-rest SPECT MPI within 1 month were retrospectively analyzed. The regions of interest were set on iodine images in accordance with the American Heart Association (AHA) 17-segment model (a total of 731 segments). The regions of interest values were divided by the amount of iodine (mg) per unit weight (kg) and defined as perfusion value (perfusion value analysis). All segments were also visually analyzed and receiver operating characteristic curve analysis performed to identify the superior analysis., Results: The receiver operating characteristic curve analysis showed that perfusion value analysis is significantly superior to visual analysis [the area under the curve: 0.921 (95% confidence interval, 0.860-0.981) versus 0.685 (95% confidence interval, 0.580-0.791), respectively, P<0.05], with 93.8% sensitivity, 99.1% specificity, 98.9% accuracy, 83.3% positive predictive value, and 99.7% negative predictive value (P<0.01)., Conclusions: Quantitative analysis of the iodine image of rest DECT, called perfusion value analysis, is more accurate than visual analysis when compared with Tc-TF SPECT MPI as the reference standard.

The simulation study was conducted for the new venous catheter with side holes of contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) to evaluate the infusion pressure on four contrast media and several injection speeds. All infusion pressure of the new venous catheter with side holes were less than 15 kg/cm 2 as limitation of extension tube and also reduced the infusion pressure by 15% at the maximum compared to the catheter with single hole. The results suggest that the new venous catheter with side holes can reduce the infusion pressure by power injection of contrast-enhanced CT and MRI.

The purpose of this study is to develop a new and simple methodology for calculating mean size-specific dose estimates (SSDE) over the entire scan range (mSSDE) from weight and volume CT dose index (CTDIvol). We retrospectively analyzed data from a dose index registry. Scan areas were divided into two regions: chest and abdomen-pelvis. The original mSSDE was calculated by a commercially available software. The conversion formulas for mSSDE were estimated from weight and CTDIvol (SSDEweight) in each region. SSDEweight were compared with the original mSSDE using Bland-Altman analysis. Root mean square differences were 1.4 mGy for chest and 1.5 mGy for abdomen-pelvis. Our method using formulae can calculate SSDEweight using weight and CTDIvol without a dedicated software, and can be used to calculate DRL to optimize CT exposure doses., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Purpose: To assess the dose reduction of radiologists by using angular beam modulation (ABM) and radiation protection drape during computed tomography (CT) fluoroscopy., Materials and Methods: The phantom was set on the lower that is 15 cm from the isocenter position. We measured the radiation exposure around the phantom with radiophotoluminescence glass dosimeters. The space radiation dose rate was measured with an ionization chamber dosimeter in the CT room., Results: The dose rate of finger radiation exposure was 67% at assumed assist tool position with ABM. And the dose rate of finger radiation exposure with the combination of ABM and radiation protection drape was 33%. The space dose rate of exposure with the combination of ABM and radiation protection drape was 49% at 150 cm., Conclusion: The combination of ABM and radiation protection drape can reduce finger radiation exposure at assumed assist tool position. The space dose rate of the standing position of radiologists can get a clear dose of radiation reduction by the combination of both.

Objective: To investigate the associations between large-joint damage and findings on fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) using the "assessment of rheumatoid arthritis by scoring of large-joint destruction and healing in radiographic imaging (ARASHI)" scoring system., Methods: A total of 270 large joints (shoulders, elbows, hips, knees, and ankles) in 27 rheumatoid arthritis patients were assessed. FDG-PET/CT was performed at the initiation of biologics. Radiographs at baseline and at 3 years were evaluated using the ARASHI score., Results: Radiographic progression of damage was detected in 35 by Larsen grade vs. 87 by the ARASHI score. The maximum standardized uptake value (SUVmax) at baseline, Steinbrocker stage at baseline, concomitant prednisolone use, and disease activity score in 28 joints based on erythrocyte sedimentation rate (DAS28-ESR) at 6 months were significantly higher in the radiographic progression group. An SUVmax higher than 1.65 at baseline was a significant predictive factor for progressive damage at 3 years., Conclusions: The ARASHI score may allow more detailed evaluation of large joints than the Larsen method. Joint destruction is likely to have progressed at 3 years in large joints, which had a higher SUVmax at the initiation of biologics.

Purpose: To investigate the incidence and risk factors of contrast induced nephropathy (CIN) after contrast enhanced (CE) computed tomography (CT) in patients with renal dysfunction., Materials and Methods: Two hundred sixteen inpatients with estimated glomerular filtration rates (eGFR) <60 ml/min/1.73 m 2 underwent CE CT using iodine doses of 420 or 480 mg I/kg. Data of all enrolled patients was collected for baseline serum creatinine level (SCr), post-CE CT SCr within 3 days after CE CT, and conditions considered risk factors for CIN [renal dysfunction, contrast media dose, advanced age, diabetes mellitus, no intravenous hydration, cardiac dysfunction (left ventricular ejection fraction <60%) and intensive-care unit (ICU) admission]. CIN was defined as an increase in SCr level of more than 0.5 mg/dl or more than 25% from baseline within 3 days post-CE CT without any other identifiable cause of acute kidney injury., Results: The incidence of CIN was 11/216 (5.1%) and was associated with cardiac dysfunction [odds ratio (OR) 6.540; 95% confidence interval (CI) 1.090-39.300; p = 0.040] and ICU admission (OR 11.500; 95% CI 2.050-64.100; p = 0.005)., Conclusion: Our results suggested that cardiac dysfunction and ICU admission may be risk factors for CIN in patients with preexisting renal dysfunction.

Background: Thyroid function in patients with Grave's disease is usually evaluated by thyroid scintigraphy with radioactive iodine. Recently, dual-energy computed tomography (DECT) with two different energy X-rays can calculate iodine concentrations and can be applied for iodine measurements in thyroid glands. This study aimed to assess the potential use of DECT for the functional assessment of the thyroid gland., Methods: Thirteen patients with Grave's disease treated at our hospital from May to September 2015 were included in this retrospective study. Before treatments, all subjects had undergone both iodine scintigraphy [three and 24 h after oral administration of 123 I (20 μCi)] and non-enhanced DECT. The region of interests (ROIs) were placed in both lobes of the thyroid glands, and CT values (HU: Hounsfield unit) and iodine concentrations (mg/mL) calculated from DECT images were measured. The correlation between CT values and iodine concentrations from DECT in the thyroid gland was evaluated and then the iodine concentrations were compared with radioactive iodine uptake ratios by thyroid scintigraphy., Results: Mean (±SD) 123 I uptake increased from 46.3 (±22.2) % (range, 11.1-80.1) at 3 h, to 66.5 (±15.2) % (range, 40.0-86.1) at 24 h (p < 0.01). CT values ranged from 34.5 to 98.7 HU [mean: 67.8 (±18.6)], while the iodine concentrations calculated with DECT ranged from 0.0 to 1.3 mg/mL [mean: 0.5 (±0.4)]. A moderate positive correlation between CT values and the calculated iodine concentrations in the thyroid gland was seen (R = 0.429, p < 0.05). A significant negative correlation between 123 I uptake at 3 h and iodine concentration by DECT were seen (R = -0.680, p < 0.05), although no correlation was observed between 123 I uptake at 3 h and CT values (p = 0.087). No correlation was observed between 123 I uptake at 24 h and CT values (p = 0.153) or that between 123 I uptake at 24 h and iodine concentration by DECT (p = 0.073)., Conclusion: The negative correlation of 123 I uptake at 3 h with iodine concentration evaluated by DECT was better than that observed with simple CT value. DECT may have a potential role in the evaluation of iodine turnover in hyperthyroid patients.

The purpose of this study was to reveal the optimal function for regression of spectral Hounsfield Unit (HU) curves. The optimization procedure consists of the following steps: 1) obtaining dual energy CT (DECT) images of the RMI 467 phantom, 2) obtaining virtual monochromatic images from DECT images, 3) mapping each region of interest (ROI) to a phantom rod on virtual monochromatic images, 4) obtaining spectral HU curves for all rods, 5) regression of spectral HU curves using various functions, including linear, quadratic polynomial, cubic polynomial, quartic polynomial, quintic polynomial, sextic polynomial, septic polynomial, exponential, corrected exponential, bi-exponential, and logarithm, and 6) calculating the coefficients and the Akaike Information Criterion (AIC) of the functions listed above. Results indicated that the quintic polynomial function is suitable for analyzing the regression of spectral HU curves. The coefficients generated by the quartic or higher order polynomial functions were significantly higher than those generated by other functions (p<0.05). The median AIC of the quintic polynomial was the lowest among all functions. Therefore, we conclude that the quintic polynomial is the best function to use for the regression of spectral HU curves.

Objective: To assess the incidence and types of sensation of smell and taste during i.v. injection of five kinds of contrast media (CM) in CT examinations., Methods: 735 patients who underwent contrast-enhanced CT (CE-CT) between 14 March 2016 and 5 April 2016 were enrolled. Medical staff asked patients whether they felt heat sensation and sensation of smell and taste during i.v. injection of CM (one of the following: iopromide, iomeprol, iopamidol, iohexol and ioversol) after their CE-CT. If the patients stated having felt the sensation of smell or taste, they were also asked what kind of smell or taste they sensed. Next, 30 ml of each CM was poured into high-purity pet cups for radiological technologists to smell directly. Radiological technologists were asked whether or not each CM had any smell., Results: The sensations of smell and taste incidence for iopromide were 24.3% and 18.9%, respectively, which were significantly higher than those for other CM (p < 0.05). The highest incidence of the sensation of smell was medicine-ish, and the most frequently noted taste was bitterness. All radiological technologists could directly smell only iopromide, which has an ether group on a side chain and fewer hydroxyl groups., Conclusion: Iopromide showed a higher incidence of sensation of smell and taste than other CM. Advances in knowledge: This was the first investigation of sensation of smell and taste during i.v. injection of CM, and a specific CM showed a higher incidence, which is suspected to be due to its chemical structure.

The aim of this study was to verify the usefulness for the dose optimisation of setting a diagnostic reference level (DRL) based on the results of a prefecture-wide multi-centre radiation dose survey and providing data feedback. All hospitals/clinics in the authors' prefecture with computed tomography (CT) scanners were requested to report data. The first survey was done in July 2011, and the results of dose-length products (DLPs) for each CT scanner were fed back to all hospitals/clinics, with DRL set from all the data. One year later, a second survey was done in the same manner. The medians of DLP in the upper abdomen, whole body and coronary CT in 2012 were significantly smaller than those of the 2011 survey. The interquartile ranges of DLP in the head, chest, pelvis and coronary CT were also smaller in 2012. Radiation dose survey with data feedback may be helpful for CT dose optimisation., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Purpose: The aim of the current study was to evaluate the utility of F-18-fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) in assessing patients diagnosed with immunoglobulin G4 (IgG4)-related disease (IgG4-RD) with inflammation of the head and neck glands., Methods: We reviewed the records of 17 patients (16 men and 1 woman) with IgG4-RD exhibiting inflammation of the head and neck glands (lacrimal or salivary glands; LSG) who were diagnosed by excisional biopsy of the LSG. F-18 FDG PET/CT images were retrospectively evaluated for locations of high FDG accumulation, and the maximum standardized uptake value (SUVmax) of each lesion was calculated., Results: In 15 of 17 patients (88 %), FDG accumulation was observed in organs outside of the biopsied LSG. High FDG accumulation was most frequently seen in the lymph node (71 %), followed by the non-biopsied LSG (41 %). FDG accumulation was also found in other typically affected organs including the prostate and retroperitoneum (18 %), kidney and lung (12 %), and pancreas (1 %). FDG accumulation was most commonly observed in two lesions outside of the biopsied site (41 %)., Conclusions: Detection of the multi-organ involvement before treatment is important for patients with IgG4-RD. F-18 FDG PET/CT is an effective tool for assessing the location of extra-LSG lesions in patients with IgG4-RD with LSG inflammation.

Unlabelled: The accurate depiction of both biologic and anatomic profiles of tumors has long been a challenge in PET imaging. An inflammation, which is innate in the carcinogenesis of oral squamous cell carcinoma (OSCC), frequently complicates the image analysis because of the limitations of (18)F-FDG and maximum standardized uptake values (SUV(max)). New PET parameters, metabolic tumor volume (MTV) and total lesion glycolysis (TLG), as well as (18)F-fluoro-α-methyltyrosine ((18)F-FAMT), a malignancy-specific amino acid-based PET radiotracer, are considered more comprehensive in tumor image analysis. Here, we showed the substantial effects of the intratumoral inflammatory process on (18)F-FDG uptake and further study the possibility of MTV and TLG to predict both tumor biology (proliferation activity) and anatomy (pathologic tumor volume)., Methods: (18)F-FDG and (18)F-FAMT PET images from 25 OSCC patients were analyzed. SUV(max) on the tumor site was obtained. PET volume computerized-assisted reporting was used to generate a volume of interest to obtain MTV and TLG for (18)F-FDG and total lesion retention (TLR) for (18)F-FAMT. The whole tumor dissected from surgery was measured and sectioned for pathologic analysis of tumor inflammation grade and Ki-67 labeling index., Results: The high SUV(max) of (18)F-FDG was related to the high inflammation grade. The SUV(max )ratio of (18)F-FDG to (18)F-FAMT was higher in inflammatory tumors (P < 0.05) whereas the corresponding value in tumors with a low inflammation grade was kept low. All (18)F-FAMT parameters were correlated with Ki-67 labeling index (P < 0.01). Pathologic tumor volume predicted from MTV of (18)F-FAMT was more accurate (R = 0.90, bias = 3.4 ± 6.42 cm(3), 95% confidence interval = 0.77-6.09 cm(3)) than that of (18)F-FDG (R = 0.77, bias = 8.1 ± 11.17 cm(3), 95% confidence interval = 3.45-12.67 cm(3))., Conclusion: (18)F-FDG uptake was overestimated by additional uptake related to the intratumoral inflammatory process, whereas (18)F-FAMT simply accumulated in tumors according to tumor activity as evaluated by Ki-67 labeling index in OSCC., (© 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Background: Positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) can detect the presence of synovitis in rheumatoid arthritis (RA) patients. The aim of this study was to investigate whether the findings of FDG-PET matched the conventional assessments of the disease activity score (DAS) 28, DAS28-CRP, simplified disease activity index (SDAI) and clinical disease activity index (CDAI) in RA patients receiving tocilizumab (TCZ) therapy., Methods: Seventeen RA patients treated with TCZ were assessed. FDG-PET was performed at baseline and three and six months after the initiation of TCZ therapy. The maximum SUV (SUVmax) of the bilateral shoulder, elbow, wrist, hip, knee and ankle joints were added together (total SUV) and were used to assess the degree of FDG uptake as a representative parameter. The correlations between the ΔSUV and the difference in the clinical parameters at baseline and at each observation period, and the differences in each clinical parameters, were assessed., Results: The ΔSUV, the differences in the total SUV at baseline and at three/six months after starting treatment positively correlated with the ΔDAS28 (r = 0.615 p = 0.009/ r = 0.775 p < 0.001), ΔDAS28-CRP (r = 0.696, p = 0.002/ r = 0.828, p < 0.001), ΔSDAI (r = 0.652, p = 0.005/ r = 0.686, p = 0.002) and ΔCDAI (r = 0.662, p = 0.004/ r = 0.711, p = 0.001) for each period. The total SUV was significantly decreased at three and six months after the initiation of TCZ (p < 0.05)., Conclusions: A reduction in the FDG uptake was observed at three and six months after the initiation of TCZ therapy. The disease activity estimated on FDG-PET/CT matched the conventional parameters following the TCZ therapy in RA patients.

It is essential for medical students to learn and comprehend human anatomy in three dimensions (3D). With this in mind, a new system was designed in order to integrate anatomical dissections with diagnostic computed tomography (CT) radiology. Cadavers were scanned by CT scanners, and students then consulted the postmortem CT images during cadaver dissection to gain a better understanding of 3D human anatomy and diagnostic radiology. Students used handheld digital imaging and communications in medicine viewers at the bench-side (OsiriX on iPod touch or iPad), which enabled "pixel-to-tissue" direct comparisons of CT images and cadavers. Students had lectures and workshops on diagnostic radiology, and they completed study assignments where they discussed findings in the anatomy laboratory compared with CT radiology findings. This teaching method for gross and radiological anatomy was used beginning in 2009, and it yielded strongly positive student perspectives and significant improvements in radiology skills in later clinical courses., (© 2014 American Association of Anatomists.)

Background: Hepatic angiomyolipoma is a rare benign mesenchymal tumor. We report an unusual case of a patient with multiple hepatic angiomyolipomas exhibiting high (18) F-fluorodeoxyglucose (FDG) uptake., Case Presentation: A 29-year-old man with a medical history of tuberous sclerosis was admitted to our hospital for fever, vomiting, and weight loss. Abdominal dynamic computed tomography revealed faint hypervascular hepatic tumors in segments 5 (67 mm) and 6 (10 mm), with rapid washout and clear borders; however, the tumors exhibited no definite fatty density. Abdominal magnetic resonance imaging revealed that the hepatic lesions were slightly hypointense on T1-weighted imaging, slightly hyperintense on T2-weighted imaging, and hyperintense with no apparent fat component on diffusion-weighted imaging. FDG-positron emission tomography (PET) imaging revealed high maximum standardized uptake values (SUVmax) of 6.27 (Segment 5) and 3.22 (Segment 6) in the hepatic tumors. A right hepatic lobectomy was performed, and part of the middle hepatic vein was also excised. Histological examination revealed that these tumors were characterized by the background infiltration of numerous inflammatory cells, including spindle-shaped cells, and a resemblance to an inflammatory pseudotumor. Immunohistochemical evaluation revealed that the tumor stained positively for human melanoma black-45. The tumor was therefore considered an inflammatory pseudotumor-like angiomyolipoma. Although several case reports of hepatic angiomyolipoma have been described or reviewed in the literature, only 3 have exhibited high (18) F-FDG uptake on PET imaging with SUVmax ranging from 3.3-4.0. In this case, increased (18) F-FDG uptake is more likely to appear, particularly if the inflammation is predominant., Conclusion: Although literature regarding the role of (18) F-FDG-PET in hepatic angiomyolipoma diagnosis is limited and the diagnostic value of (18) F-FDG-PET has not yet been clearly defined, the possibility that hepatic angiomyolipoma might exhibit high (18) F-FDG uptake should be considered.

Objectives: Adenocarcinoma in situ (AIS), which is considered to be pathologically non-invasive in the new International Association for the Study of Lung Cancer/the American Thoracic Society/the European Respiratory Society classification, might be present in patients who show a part-solid nodule on thin-section computed tomography (CT) scan., Methods: Between 2008 and 2011, 556 clinical Stage IA (c-Stage IA) lung cancer patients underwent pulmonary resection. For all the patients, the findings obtained by preoperative thin-section CT were reviewed and categorized as pure ground-glass nodule (GGN), part-solid nodule or pure-solid nodule based on the findings on thin-section CT, i.e. based on the consolidation/tumour ratio (CTR). A part-solid nodule was defined as a tumour with 0 < CTR < 1.0, which indicated focal nodular opacity that contained both solid and GGN components. All the patients were evaluated by positron emission tomography (PET), and the maximum standardized uptake value (SUVmax) was recorded. Several clinicopathological features were investigated to identify predictors of AIS in clinical Stage IA lung cancer patients with a part-solid nodule radiologically, using multivariate analyses., Results: One-hundred and twelve c-Stage IA lung cancer patients showed a part-solid appearance on thin-section CT. Among them, AIS was found in 10 (32%) of the tumours with 0 < CTR ≤ 0.5, in contrast to 3 (5%) with 0.5 < CTR < 1.0. According to multivariate analyses, SUVmax and CTR significantly predicted AIS in patients with a part-solid nodule (P = 0.04, 0.02). The mean SUVmax of the patients with AIS was 0.57 (0-1.6). Moreover, in the subgroup of part-solid nodule with a SUVmax of ≤1.0 and a CTR of ≤0.40, which were calculated as cut-off values for AIS based on the results for a receiver operating characteristic curve, 6 (40%) patients with these criteria showed a pathological non-invasive nature, even patients with a part-solid nodule., Conclusions: Among c-Stage IA adenocarcinoma with a part-solid nodule on thin-section CT scan, an extremely low level of SUVmax could reflect a pure GGN equivalent radiologically and AIS pathologically. The preoperative tumour SUVmax on PET could yield important information for predicting non-invasiveness in patients with a part-solid nodule.

A 62-year-old male presented with sudden onset of low back and right leg pain. Contrast-enhanced computed tomography demonstrated an abdominal aortic aneurysm (AAA), along with a large mass lesion causing vertebral body erosion. Magnetic resonance imaging (MRI) suggested that the mass lesion consisted of a chronic hematoma. Fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) demonstrated increased uptake around the mass lesion, but not around the AAA. Surgical intervention was performed, and the subsequent histological diagnosis was chronic contained rupture of AAA. The mass lesion consisted of chronic hematoma and necrosis with inflammatory cell infiltration and hemosiderin deposition. This condition mimics some neoplastic diseases, but MRI and FDG-PET findings may help establish the correct diagnosis.

Purpose: The objective of this study was to characterize cervical computed tomography (CT) findings in Kawasaki disease (KD) patients that may facilitate early diagnosis., Methods: We retrospectively reviewed cervical CT images of 78 children with cervical lymphadenopathy to analyze the distribution and morphology of lymphadenopathy and other soft-tissue findings., Results: Twenty-eight patients were diagnosed with KD. Fifty had other diseases (non-KD). Retropharyngeal edema was observed in 82% (23/28) of KD and 30% (15/50) of non-KD (P < 0.01) cases. Retropharyngeal lymphadenopathy was observed in 89% (25/28) of KD and 48% (24/50) of non-KD (P < 0.01) cases. Levels III and IV lymphadenopathy was found in only 1 KD case, whereas levels III and IV lymphadenopathy was found in 58% (29/50) (P < 0.01) and 36% (18/50) (P < 0.01) of non-KD cases, respectively., Conclusions: Retropharyngeal lymphadenopathy and retropharyngeal edema are relatively common features of KD on CT. Given the potentially serious complications of KD, this diagnosis is an important consideration in a young child presenting with these imaging findings.

Purpose: The aim of this study was to investigate the feasibility of separately evaluating bronchial (BAP) and pulmonary arterial perfusion (PAP) of lung cancers using dual-input perfusion computed tomography., Materials and Methods: Twenty-nine lesions from 28 patients [19 men and 9 women; age, 65.8±11.3 y (mean±SD); range, 39 to 85 y] were included in this study (1 patient had 2 tumors). From computed tomography data, quantitative maps of PAP and BAP were created using the dual-input maximum-slope method. Total blood perfusion (TBP) was defined as the sum of PAP and BAP, and the percentage of PAP to TBP was defined as %PAP. Correlation of these values with tumor size, location, and pathologic type was statistically analyzed., Results: PAP ranged from 2.0 to 93.1 mL/min/100 mL (mean±SD, 26.8±26.4), BAP was 0 to 65.4 (25.1±19.12), TBP was 20.7 to 132.0 (52.0±29.0), and %PAP was 4% to 100% (48.8%±31.9%). PAP, TBP, and %PAP correlated negatively with tumor size (P<0.05). PAP and %PAP were higher in the peripheral zone than in the central zone (P<0.05). There was significant correlation between pathologic type and the respective perfusion parameters (P>0.05)., Conclusions: We were successful in separating the dual vascular supply to assess dual-input perfusion of lung cancer. We found perfusion of lung cancers to depend on tumor size and location. Acknowledging and assessing the dual vascular supply in lung perfusion may have clinical implications in the management of lung cancer treatment.

Objective: L-3-[(18)F]-fluoro-α-methyl tyrosine ((18)F-FAMT) is an amino acid tracer for positron emission tomography/computed tomography (PET/CT) which specifically transported into cancer cells by L-type amino acid transporter 1 (LAT1). LAT1 overexpression in tumors is significantly correlated with cell proliferation and angiogenesis. (18)F-FAMT PET/CT, fluorine-18-fluorodeoxyglucose ((18)F-FDG) PET/CT and magnetic resonance imaging (MRI) were compared for their diagnostic performance in the detection of bone marrow invasion in patients with oral squamous cell carcinoma (OSCC)., Methods: Twenty-seven patients with OSCC on the upper or lower alveolar ridge underwent staging by MRI, (18)F-FDG PET/CT and (18)F-FAMT PET/CT studies before surgery. Post-surgical pathologic examination was used as the standard to determine the final diagnoses. The possibility of bone marrow invasion on MRI, (18)F-FDG PET/CT and (18)F-FAMT PET/CT were usually graded retrospectively into five-point score. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated according to the obtained scores., Results: As the sensitivity of (18)F-FDG PET/CT was highest (100 %) among that of MRI (95 %) and (18)F-FAMT PET/CT (90 %), the specificity of (18)F-FAMT PET/CT was highest (85.7 %) among that of MRI (57 %) and (18)F-FDG PET/CT (14.3 %). The size of pathological tumor was accorded with that detected by (18)F-FAMT PET/CT and was smaller than that detected by (18)F-FDG PET/CT (P < 0.01). Significant difference was not found between (18)F-FAMT PET tumor volume and pathological tumor volume., Conclusions: (18)F-FAMT PET/CT was useful and more specific than MRI or (18)F-FDG PET/CT in the detection of bone marrow invasion of OSCC and may contribute to minimize the extent of resection in oral surgery patient.

Background: We performed this study in order to investigate the shape of the origin of the celiac artery in maximum intensity projection (MIP) using routine 64 multidetector-row computed tomography (MDCT) data in order to plan for the implantation of an intra-arterial hepatic port system., Methods: A total of 1,104 patients with hepatocellular carcinoma were assessed with MDCT. In the definition of the branching angle, the anterior side of the abdominal aorta was considered the baseline, and the cranial and caudal sides were designated as 0 and 180 degrees, respectively. The angles between 0 and 90 degrees and between 90 and 180 degrees from the cranial side were considered upward and downward, respectively, and the branching angle of the celiac artery was classified every 30 degrees. The subclavian arterial route was used for the implantation of an intra-arterial hepatic port system in patients with branching angles of 150 degrees or more (sharp downward)., Results: The median branching angle was (median ± standard deviation) 135 ± 23 (range, 51-174) degrees. The branching was upward in 77 patients (7%) and downward in 1,027 patients (93%). The branching was downward with an angle of 120 to 150 degrees in most patients (n = 613). The branching was sharply downward with an angle of 150 degrees or more in 177 patients (16%). A total of 10 patients were referred for interventional placement of an intra-arterial hepatic port system. The subclavian arterial route was used for implantation of an intra-arterial hepatic port system in 2 patients with sharp downward branching., Conclusions: The branching angle of the celiac artery can be easily determined by the preparation of MIP images from routine MDCT data. MIP may provide useful information for the selection of the catheter insertion route in order to avoid a sharp branching angle of the celiac artery.

Optimisation of computed tomography (CT) parameters is important in avoiding excess radiation exposure. The aim of this study is to establish the diagnostic reference levels (DRL) of CT in Japan by using dose-length product (DLP). Datasheets were sent to all hospitals/clinics which had CT scanner(s) in Gunma prefecture. Data were obtained for all patients who underwent CT during a single month (June 2010), and the distributions of DLP were evaluated for eight anatomical regions and five patient age groups. The DRL was defined as the 25th and 75th percentiles of DLP. Datasheets were collected from 80 of 192 hospitals/clinics (26 090 patients). DLP for head CT of paediatric patients tended to be higher in Japan compared with DRLs of paediatric head CTs reported from the EU or Syria. Although this study was performed with limited samples, DLP for adult patients were at comparable levels for all anatomical regions.

Objectives: To evaluate whether there is a correlation between the differences in joint uptake of 2-[18F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) and the improvement of clinical findings in RA patients undergoing anti-TNF therapies., Methods: Twenty-two patients who received anti-TNF therapies, including infliximab for 16 patients and etanercept for 6 patients, were assessed. PET with (18)F-FDG studies and clinical assessments were performed at baseline and 6 months after the initiation of therapy. The maximal standardized uptake value (SUV(max)) was used as a representative value for the assessment of the FDG uptake in the bilateral shoulder, elbow, wrist, hip, knee and ankle joints. Spearman's rank correlation test was applied to assess the correlation between the SUV and the clinical parameters., Results: The ΔSUV (12 joints), the difference in the SUV(max) of the affected 12 joints before and after treatment, was positively correlated with the ΔDAS28 (r = 0.609, P = 0.003), ΔDAS28-CRP (r = 0.656, P = 0.001) and Δtender joint count (TJC) (r = 0.609, P = 0.003). There were also significantly positive correlations between ΔSUV (8 joints); the difference in the SUV(max) of the bilateral shoulder, elbow, wrist and knee joints before and after treatment and the ΔDAS28 (r = 0.642, P = 0.001), ΔDAS28-CRP (r = 0.712, P < 0.001) and ΔTJC (r = 0.608, P = 0.003), respectively., Conclusion: The FDG uptake observed in the inflamed RA joints may reflect disease activity. The FDG-PET response was correlated with the clinical response to the biologic treatment of RA.

Osteoid osteoma (OO) is a common benign bone tumor, usually found in children and young adults. Fewer than 30 cases of multicentric OO in a single bone have been reported in the world literature. We present the case of a 17-year-old boy with OO in the left tibia, containing double nidi. Plain radiography and computed tomography (CT) revealed two adjacent nidi surrounded by bony sclerosis within the distal left tibia. The tumor was successfully treated using two separate CT fluoroscopy-guided percutaneous radiofrequency ablations during a single session. The patient achieved complete pain relief the next day, and has remained asymptomatic for 9 months since treatment.

We developed a novel coaxial system using a fine guide needle wire (GNW) to safely and easily place the radiofrequency needle under CT-guidance. The GNW consists of a fine needle (diameter, 21-gauge; length, 150 mm) and a wire (0.018 inch, 250 mm). An exclusive radiofrequency cannula (14-gauge; 160 mm) was also used. This system was used for the treatment of six hepatocellular carcinomas in six patients. All lesions were located deeper than 10 cm from the needle entry site. This system was useful in performing CT-guided RF ablation for deeply or precariously located liver lesions particularly in patients who are unable to hold their breath.

A 63-year-old man underwent computed tomography (CT) using intravenous low-osmolar iodine contrast medium (LOCM) 6 days after undergoing high-dose (131)I-MIBG therapy for metastatic pheochromocytoma. Immediately after the CT examination, his blood pressure increased to 260/160 mmHg (from 179/101 mmHg before the examination). Phentolamine mesilate was administered, and the blood pressure rapidly went back to normal. Although hypertensive crisis after administration of LOCM is rare, this case suggests that high-dose (131)IMIBG therapy may be a risk factor for hypertensive crisis after administration of intravenous LOCM.

An asymptomatic 77-year-old man presented with a mass in his right thoracic paravertebral region. Calcification was not detected in the tumor on initial computed tomography. However, the tumor grew rapidly and calcification subsequently appeared. Surgical resection was performed, and the histological diagnosis was extraskeletal osteosarcoma of the pleura. Only a few cases of primary pleural extraskeletal osteosarcoma have been reported in the literature, and there have been few descriptions of the imaging features. Extraskeletal osteosarcoma should be included in the differential diagnosis of older men with rapidly growing mass lesions derived from the pleura.

Background: Computed tomography (CT) is the largest source of medical radiation exposure to the general population, and is considered a potential source of increased cancer risk. The aim of this study was to assess the current situation of CT use in Japan, and to investigate variations in radiation exposure in CT studies among institutions and scanners., Methods: Data-sheets were sent to all 126 hospitals and randomly selected 14 (15%) of 94 clinics in Gunma prefecture which had CT scanner(s). Data for patients undergoing CT during a single month (June 2008) were obtained, along with CT scan protocols for each institution surveyed. Age and sex specific patterns of CT examination, the variation in radiation exposure from CT examinations, and factors which were responsible for the variation in radiation exposure were determined., Results: An estimated 235.4 patients per 1,000 population undergo CT examinations each year, and 50% of the patients were scanned in two or more anatomical locations in one CT session. There was a large variation in effective dose among hospitals surveyed, particularly in lower abdominal CT (range, 2.6-19.0 mSv). CT examinations of the chest and upper abdomen contributed to approximately 73.2% of the collective dose from all CT examinations. It was estimated that in Japan, approximately 29.9 million patients undergo CT annually, and the estimated annual collective effective dose in Japan was 277.4 *103 Sv person. The annual effective dose per capita for Japan was estimated to be 2.20 mSv., Conclusions: There was a very large variation in radiation exposure from CT among institutions surveyed. CT examinations of the chest and upper abdomen were the predominant contributors to the collective dose.

Purpose: To describe clinical and computed tomography (CT) findings of isolated dissection of the visceral arteries (IDVA)., Materials and Methods: We retrospectively analyzed clinical presentation and abdominal CT findings of 38 patients who were diagnosed as having an IDVA. IDVA were classified into three types based on CT findings: patent false lumen with re-entry (type I), patent false lumen without re-entry (type II), and completely thrombosed false lumen (type III)., Results: The dissection was located in the superior mesenteric artery (SMA) in 27 patients, celiac artery (CA) in 6, CA to splenic artery in 2, and common hepatic artery (CHA), CA to CHA, and inferior mesenteric artery (IMA) in 1 patient each. The dissection was classified into type I in 8 patients, type II in 12, and type III in 18. Surgical treatment was performed in 1 patient with type II SMA dissection because of bowel ischemia, although the remaining 37 patients were managed conservatively. Two cases with type II showed a progressive enlargement of the false lumen in follow-up CT. Increased density of the fat tissue around the affected visceral artery was more commonly seen in symptomatic patients compared to asymptomatic ones (P < 0.01)., Conclusion: Based on our observation, patients with IDVA can be managed conservatively when there are no signs indicating organ ischemia.

Purpose: The aim of this study was to compare the maximum-slope (MS) and dual-input one-compartment model (DOCM) methods in hepatic perfusion computed tomography (CT)., Materials and Methods: A total of 37 patients with known or suspected liver disease underwent single-location dynamic CT after arterial or venous bolus injection of contrast material. Perfusion CT images were created by the MS (dividing the peak gradient of the time-attenuation curve by the peak vessel CT number) and DOCM-calculating from the equation dC ( L )(t)/dt = k ( a ) C ( a )(t - tau( a )) + k ( p ) C ( p )(t - tau( p )) - k ( v ) C ( L )(t)-methods. The perfusion parameters hepatic arterial perfusion (HAP), portal venous perfusion (PVP), and hepatic perfusion index (HPI) were determined., Results: The PVP of the tumor-free hepatic parenchyma determined by the MS method was lower than that obtained by the DOCM method (P < 0.001) with both injections. HAP determined by the MS method was lower than that obtained by the DOCM method with venous injection (P = 0.001), although there was no difference between the methods for HAP with arterial injection (P = 0.154). Most of the perfusion parameters showed linear correlations between the two analytical methods., Conclusion: Except for HAP with arterial injection, the perfusion parameters obtained with the MS method were lower than those obtained with the DOCM method.

Objective: To evaluate whether [F-18] fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can distinguish benign from malignant solitary pulmonary nodules (SPNs) with non-solid components., Methods: [F-18] FDG-PET/CT scans were performed on 53 consecutive patients (30 men, 23 women; mean age 65 years) who had SPNs with non-solid components identified by CT screening for lung cancer. All patients underwent surgical resection, and all lesions were pathologically proved. Visual score, maximal, and mean standardized uptake value (SUV), and maximal and mean lesion-to-normal tissue count density ratio (LNR) were calculated in all lesions. In addition, clinical characteristics, laboratory test results, and CT findings were assessed., Results: Benign SPNs with non-solid components had a higher uptake on [F-18] FDG-PET/CT. Visual score, maximal and mean SUV, and maximal and mean LNR were significantly higher in the benign when compared with the malignant SPNs (P < 0.001). When the cutoff of 1.5 was assigned for maximal SUV, the diagnostic performance of [F-18] FDG-PET/CT in predicting benign SPN revealed 100.0% sensitivity, 96.4% specificity, and 100.0% accuracy., Conclusions: [F-18] FDG-PET/CT is useful for the differential diagnosis of SPNs with non-solid components.

A 37-year-old woman presented with a painful mass lesion in her right inguinal region, 6 days after normal vaginal delivery. Computed tomography and magnetic resonance imaging showed a serpentine mass lesion containing blood elements along the inguinal course of the round ligament continuous to the labium majus. Although thrombosed varices of the round ligament is a rare condition, it should be distinguished from other inguinal masses to prevent unnecessary surgical treatments.

Air embolism is a rare but potentially fatal complication of percutaneous needle biopsy of the lung. We report a case of cerebral air embolism which occurred during computed tomography (CT)-guided needle biopsy. Air entering the aorta is depicted on CT-fluoroscopy images of the procedure.

Rationale and Objectives: Our goals were to apply perfusion CT technique to breast tumor and to evaluate the correlation between arterial perfusion value and other tumor characteristics., Materials and Methods: Thirty-one female patients with primary breast tumors were included in this study. A single-slice dynamic CT was performed after an intravenous bolus injection of contrast material (40 ml; 370 mg I/ml) at 8 ml/sec. The parameters were calculated on a pixel-by-pixel basis by using maximum slope method, and quantitative maps of arterial perfusion were created. Statistical correlation between tumor size, patient age, and perfusion were assessed. Differences in perfusion between scirrhous and nonscirrhous carcinoma were also assessed., Results: Perfusion CT images were successfully created for 24 patients (mean age, 55.9 years old; range, 36-85 years). In five patients, dynamic CT was not performed due to lack of visualization of the breast tumor on unenhanced CT. In two patients, reliable perfusion CT image could not be created because of motion artifact. The mean perfusion for 24 tumors was 33.1 +/- 16.9 ml/min/100 ml (mean +/- SD; range, 14-78), and the tumor perfusion did not correlate with patient's age or tumor size (21.0 +/- 10.2 mm; range, 10-45 mm). The mean perfusion of nonscirrhous carcinoma (45.8 ml/min/100 ml; n = 11) was higher than that of scirrhous carcinoma (22.7 ml/min/100 ml; n = 11; P < .001)., Conclusion: Determination of the perfusion of breast carcinoma is feasible by dynamic CT and can be performed during a routine CT study without much supplementary burden on the patient. There are differences in blood flow between scirrhous and nonscirrhous breast carcinoma, and further research is needed to determine the impact of this finding.

Rationale and Objectives: We sought to determine the relationship between tumor blood flow and glucose uptake in head and neck tumors using perfusion computed tomography (PCT) and fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)., Materials and Methods: Institutional review board approval and informed consent were obtained for this study. Sixteen patients (mean age, 67 years; age range, 36-89 years) who had known or suspected head and neck tumors (15 malignant tumors and one schwannoma) underwent PCT and FDG PET examinations. Tumor area was measured on conventional CT images. The PCT data were postprocessed using maximum slope method analysis, and standardized uptake value (SUV) was measured on FDG PET., Results: Mean arterial perfusion of the tumors was 61.56 mL/min/100 mL (range 22.17-102.7 mL/min/100 mL), and mean FDG SUV was 7.48 (range 2.74-17.1). A significant negative correlation between arterial perfusion and FDG SUV was found for malignant tumors (r = -0.538, P = .04, n = 15)., Conclusion: There was an inverse relationship between arterial perfusion and glucose uptake of head and neck malignant tumors, suggesting that the malignant tumors may depend on anaerobic glycolysis.

When interpreting enhanced computer tomography (CT) images of the upper abdomen, radiologists visually select a set of images of the same anatomical positions from two or more CT image series (i.e., non-enhanced and contrast-enhanced CT images at arterial and delayed phase) to depict and to characterize any abnormalities. The same process is also necessary to create subtraction images by computer. We have developed an automated image selection system using a template-matching technique that allows the recognition of image sets at the same anatomical position from two CT image series. Using the template-matching technique, we compared several anatomical structures in each CT image at the same anatomical position. As the position of the liver may shift according to respiratory movement, not only the shape of the liver but also the gallbladder and other prominent structures included in the CT images were compared to allow appropriate selection of a set of CT images. This novel technique was applied in 11 upper abdominal CT examinations. In CT images with a slice thickness of 7.0 or 7.5 mm, the percentage of image sets selected correctly by the automated procedure was 86.6+/-15.3% per case. In CT images with a slice thickness of 1.25 mm, the percentages of correct selection of image sets by the automated procedure were 79.4+/-12.4% (non-enhanced and arterial-phase CT images) and 86.4+/-10.1% (arterial- and delayed-phase CT images). This automated method is useful for assisting in interpreting CT images and in creating digital subtraction images.

Background: To evaluate the role of computed tomography (CT) -guided needle biopsy and sodium iodide fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in the investigation of solitary pulmonary nodules (SPN), which are discovered on screening chest radiographs, and to determine the cost-effectiveness of these modalities., Material/methods: We have used decision-tree analysis models to assess the accuracy and cost-effectiveness of four strategies for the diagnosis and management of SPNs: CT alone strategy (baseline), CT plus FDG-PET strategy, CT plus FDG-PET plus CT-guided needle biopsy strategy, and CT plus CT-guided needle biopsy strategy. Reported values of prevalence of cancer, and sensitivity and specificity of each diagnostic modality were applied to the decision-tree models using Japanese health care costs., Results: The prevalence of lung cancer among SPNs discovered on the lung cancer screening was less than 10%. In this prevalence, the strategies using CT-guided needle biopsy were the cost-effective alternatives to the CT alone strategy (cost saving was 436,470 yen - 456,478 yen per patient), and had higher accuracies (95-96% vs. 67%). Both effects were mainly the result of reducing the number of the candidates who undergo unnecessary thoracotomy for a benign SPN, and these results were true over a wide range of prevalence of cancer (0-55%). The cost saving and accuracy of the CT plus FDG-PET strategy (359,206 and 92%) were approaching to those of the strategies using CT-guided needle biopsy., Conclusions: The introduction of CT-guided needle biopsy and FDG-PET for the evaluation of SPNs, which are discovered on screening chest radiograph, is potentially cost-effective in Japan with high accuracy.

Rationale and Objectives: To apply perfusion computed tomography (CT) technique to variable malignant liver tumors, and to define the usefulness of quantitative color mapping., Materials and Methods: Perfusion CT images were created for 36 malignant liver tumors in 28 patients (age, 66.4 +/- 10.1 years; range, 48-85) with metastatic liver tumors (n = 17; nine colorectal carcinomas, eight other malignant tumors) and hepatocellular carcinomas (n = 11). A single-slice dynamic CT was performed after an intravenous bolus injection of 40 mL of contrast material (320 mgI/mL) with 8 mL/sec. The parameters were calculated pixel-by-pixel using maximum slope method, and quantitative maps of arterial and portal perfusion were created. In four patients who underwent transcatheter arterial chemoembolization, perfusion CT was performed before and after transcatheter arterial chemoembolization., Results: In all patients, liver tumors were shown as hypervascular lesions on arterial perfusion CT. The average arterial perfusion value of the metastatic tumors from the colorectal carcinomas was 0.67 +/- 0.33 mL/min/mL, and that of hepatocellular carcinomas was 0.94 +/- 0.26 mL/min/mL (P = .03). The other metastatic tumors from various primary tumors showed a wide range (0.19-1.45 mL/min/mL) of arterial perfusion. Arterial perfusion of the liver tumors was obviously decreased after successful transcatheter arterial chemoembolization. In 12 of 15 tumors, in which portal perfusion CT images could be created, region-of-interest analysis showed no portal perfusion in the tumors. In two cases, decreased portal perfusion in the segments, which malignant tumors involved, was demonstrated., Conclusion: Perfusion CT can provide quantitative information about arterial and portal perfusion of liver tumors, combined with good anatomic detail in one image. This technique has a potential to evaluate the angiogenesis of liver tumors, to show secondary changes in perfusion, such as decreased portal perfusion in apparently normal liver adjacent to metastases, and to monitor the therapeutic response in vivo.

Aim: To improve liver-perfusion imaging by using the dual-input one-compartmental model., Methods: Single-level dynamic computed tomography (dynamic CT) was taken at the height of the hepatic hilum after a rapid intravenous injection using 40 ml of iodinated contrast material. From the time-density curve of each pixel on CT, we calculated blood-flow rate constants of liver inflow and outflow. For inflow, two constants were calculated at arterial and portal veins. We postulated that blood flow between hepatic vessels and the hepatic parenchyma could be analyzed by using the calculated constants, and made equations for liver perfusion mapping. The perfusion images obtained by this method were compared with those made by the maximum slope method., Results: We applied the method to a patient with hepatolithiasis. On dynamic CT, there was an abnormal enhancement pattern in the posterior segment of the liver. Perfusion CT images made by the dual-input one-compartment model demonstrated abnormal portal perfusion of the liver. In contrast, those made by the maximum-slope method did not represent the perfusion pattern well., Conclusion: The dual-input one-compartmental model makes it possible to obtain more detailed information on liver hemodynamics.

Rationale and Objectives: To correlate the presence of fatty liver and the enhancement value of liver tissue during portal phase computed tomography., Materials and Methods: Liver tissue enhancements during portal phase computed tomography were measured in 16 fatty liver and 35 control patients. All patients intravenously received 100 mL of non-ionic contrast material (320 mg iodine/ mL) at a rate of 3 mL/second, and the image acquisition started at 70 seconds. Attenuation values were measured on the 80-second portal phase images and the corresponding unenhanced images, and the contrast enhancement value (HU) of the liver tissue was calculated. Adjusted enhancement values were also calculated with the following equation: adjusted enhancement value = enhancement value (HU)/[dose (grams of iodine)/body weight (kg)]., Results: The contrast enhancement value was significantly reduced in the fatty liver patients compared with the normal controls (37.0 +/- 7.2 vs 49.8 +/- 12.0 HU; P < .0001). This difference was still significant in adjusted enhancement value (80.1 +/- 13.7 vs 93.6 +/- 23.0 HU kg g(-1); P = .01)., Conclusion: The liver tissue with fatty infiltration was less enhanced than controls, probably because of decreased portal perfusion.

Rationale and Objectives: The purpose of this study was to develop and test a method for evaluating the effect of diagnostic tests on physicians' diagnostic thinking., Materials and Methods: The authors applied the method to data obtained in a previous study. The diagnoses of surgeons in the emergency department before and after contrast material-enhanced computed tomography (CT) and their certainty were collected from the cases of 125 adult patients with acute abdominal pain. When the pre- or post-CT diagnosis was not consistent with the final diagnosis, the diagnostic certainty reported by a physician was converted to a negative value (true diagnostic certainty). Change in true diagnostic certainty was calculated by subtracting the values for diagnostic certainty before CT from those after CT., Results: In 118 cases, the change in true diagnostic certainty was positive, which indicates that the CT information was beneficial for the physician's diagnostic thinking. The true diagnostic certainty before CT was 32.9% +/- 57.6 (range: -90% to 100%; 95% confidence interval: 22.7%, 43.1%) and that after CT was 73.4% +/- 37.0 (range: -80% to 100%; 95% confidence interval: 66.8%, 80.0%; P < .0001). Thus, the increase in true diagnostic certainty was 40.5% +/- 58.8 (range: -160% to 170%; 95% confidence interval: 30.1%, 69.2%)., Conclusion: This method may be useful for estimating the effect of diagnostic tests on physicians' diagnostic thinking in variable conditions.

We present two cases, in which perfusion CT demonstrated diffusely increased arterial and decreased portal perfusion of the liver parenchyma around liver abscess and infectious bilomas. These cases suggested that perfusion CT may be useful for a quantitative analysis of perfusion changes in infectious hepatobiliary diseases with good anatomical detail.

Rationale and Objectives: The authors developed software for creating quantitative maps of arterial and portal perfusion in the upper abdominal organs on personal computers. The image quality of these perfusion computed tomographic (CT) images was visually evaluated., Materials and Methods: In 58 patients (38 men, 20 women; mean age, 63.9 years +/- 11.9; range, 22-85 years) with various diseases of the upper abdomen, 91 single-section dynamic CT studies were obtained. The data were transferred on-line to a personal computer, and quantitative maps of arterial and portal perfusion were created by means of the maximum-slope method. Perfusion CT images were reviewed by a radiologist and a radiation technologist, and image quality was rated according to a four-category scoring system (1 = good quality, 2 = moderate, 3 = poor, 4 = images could not be created)., Results: Arterial perfusion CT images could be created in 81 (89%) of 91 examinations, and 74 images (81%) were scored as 1 or 2. Portal perfusion CT images could be created in 60 (68%) of 88 examinations, in which a portal trunk was included in the section, and 33 of them (38%) were scored as 1 or 2. Patient motion during dynamic CT sequences resulted in poor image quality in seven arterial and 27 portal perfusion images., Conclusion: Perfusion CT can combine quantitative perfusion maps with good anatomic detail in one image, although patient movement frequently degrades image quality in portal perfusion CT.

Aim: To determine the impact of computed tomography (CT) on the diagnosis and treatment plan in patients with acute abdominal pain., Materials and Methods: A prospective study was undertaken in 125 adult patients presenting with acute abdominal pain (74 men and 51 women; 40.2 +/- 19.3 years; range, 18-92). Changes in diagnosis, gain in percentage diagnostic certainty and changes of treatment plan of the surgeons in the emergency department before and after CT were evaluated. Pre- and post-CT diagnoses were compared with the final diagnoses., Results: CT findings changed the initial diagnosis in 40 (32.0%) patients. The diagnostic certainty was 58.3 +/- 22.9% before CT, and its gain after CT was 21.9 +/- 18.5 points (P < 0.0001). Post-CT diagnoses were consistent with the final diagnosis in 116 patients (92.8%), while pre-CT diagnoses were correct in 89 patients (71.2%; P < 0.0001). Initial treatment plans were changed in 31 (24.8%) patients after CT. In 57 (45.6%) patients, CT information changed diagnoses and/or treatment plans. No significant differences were observed in the diagnosis, diagnostic certainty and treatment plan among four surgeons., Conclusion: Contrast-enhanced CT frequently changed the clinical diagnoses with increased diagnostic certainty and the initial treatment plans., (Copyright 2002 The Royal College of Radiologists.)