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OBJECTIVE. We reviewed a retrospective series of 126 18F-fluciclovine PET/CT studies of patients with biochemically recurrent prostate cancer at low (< 1 ng/mL) and very low (< 0.3 ng/mL) prostate-specific antigen (PSA) levels. CONCLUSION. The rate of PET/CT positivity was 33% (15/46) in patients with low PSA levels and 0% (0/17) in patients with very low PSA levels. Our results suggest that 18F-fluciclovine PET/CT can be helpful for localizing recurrence in patients with PSA levels between 0.3 and 1 ng/mL and that 18F-fluciclovine PET/CT is not recommended in patients with PSA levels less than 0.3 ng/mL.

OBJECTIVE. The purpose of this study was to determine whether contrast medium volume and method of administration and baseline estimated glomerular filtration rate influence the efficacy of prophylactic hydration for prevention of acute kidney injury after contrast administration. MATERIALS AND METHODS. An online search of PubMed conducted on August 25, 2017, produced a total of 697 studies. After the reports were reviewed, nine were included in this study. The extracted data on all patients in these studies were separated into a group that received prophylactic hydration and a group that did not. The following three parameters were used for subgroup analysis: contrast medium volume, contrast administration method, and baseline estimated glomerular filtration rate. The t test was performed, and study-level odds ratios with 95% CIs and p values were calculated. Tests of heterogeneity were conducted. RESULTS. When the volume of contrast agent administered exceeded 100 mL, hydration was beneficial in the prevention of contrast-induced acute kidney injury (odds ratio, 0.546). If the volume was less than 100 mL, hydration had no efficacy in preventing contrast-induced acute kidney injury (odds ratio, 0.917). Administration route and baseline estimated glomerular filtration rate exerted no effect on the efficacy of prophylactic hydration. CONCLUSION. For patients who receive less than 100 mL of contrast medium, the prevalent practice for contrast-enhanced CT studies, prophylactic hydration may not be necessary, regardless of the estimated glomerular filtration rate or route of contrast administration. For patients undergoing procedures requiring administration of large volumes of contrast medium, however, hydration is recommended to prevent contrast-induced acute kidney injury.

OBJECTIVE. This study aims to compare the diagnostic accuracy of virtual unenhanced CT images derived from dual-source dual-energy contrast-enhanced CT with that of standard unenhanced CT images for evaluation of sialolithiasis. MATERIALS AND METHODS. All dual-energy CT studies of the neck performed during the preceding 5 years were reviewed for submandibular gland calculi. Only patients who had unenhanced CT and contrast-enhanced CT performed as part of the same evaluation were included in this study. This review yielded 30 patients. Virtual unenhanced CT images were derived from the dual-energy dataset and compared with the true unenhanced CT images by two separate radiologists who assessed the total number of calculi encountered, their location, the largest dimension, and the attenuation of the calculi. The radiation burden incurred for true unenhanced CT and virtual unenhanced CT and the total radiation burden were calculated. RESULTS. Our analysis revealed that measurements of stone size showed good interobserver agreement. The mean stone size was 7.9 ± 5.9 (SD) mm on virtual unenhanced CT and 8.4 ± 5.9 mm on true unenhanced CT (range, 2.0-31.8 mm); the difference was statistically insignificant. The mean stone attenuation differed considerably (p < 0.01) between the virtual and true unenhanced CT images (494.8 ± 187.5 HU and 924.4 ± 374.9 HU, respectively), but correlated well. The mean radiation dose for a dual-phase IV contrast-enhanced CT study was 23.13 mGy (volume CT dose index). The mean dose was 10.93 mGy for the true unenhanced CT phase, thereby suggesting a 47.25% reduction in administered radiation dose when a single-phase contrast-enhanced CT study with virtual unenhanced image reconstructions is performed. CONCLUSION. Virtual unenhanced CT images derived from dual-source dual-energy CT scans of the neck provide accurate assessment of sialolithiasis akin to that provided by conventional CT protocols but at only a fraction of the radiation dosage.

OBJECTIVE. The objective of our study was to evaluate the clinical utility of FDG PET/CT in staging and restaging pediatric patients with yolk sac tumor (YST). MATERIALS AND METHODS. We retrospectively reviewed the data from 31 pediatric patients with pathologically confirmed YST who underwent 34 PET/CT studies for the purpose of staging or restaging. The PET/CT studies were read by two nuclear medicine doctors in consensus. Histopathology combined with clinical and imaging follow-up was taken as the reference standard. The results of PET/CT were also compared with conventional imaging and α-fetoprotein (AFP) levels when available. RESULTS. Of the total 34 studies, six were performed for initial staging and the other 28 for posttherapy evaluation. FDG PET/CT was true-positive in all six staging studies, detected only a few more metastatic foci than conventional imaging, and changed the therapeutic regimen in none of the six patients. Nevertheless, PET/CT showed high accuracy in the restaging group, with a sensitivity of 100% and specificity of 85.7%. The treatment regimen was changed in 46.4% of the patients in the restaging group according to the PET/CT study. In addition, PET/CT had higher accuracy than AFP levels in YST restaging. Overall, the per-study performance of PET/CT was a sensitivity of 100%, specificity of 85.7%, positive predictive value of 90.9%, and negative predictive value of 100%. CONCLUSION. FDG PET/CT was only slightly superior to conventional imaging in staging YST in pediatric patients. However, PET/CT of posttherapy patients with YST showed high diagnostic accuracy and had a great impact on therapeutic management.

We aimed to explore proportion, involved organisms, and serial CT features of nodular bronchiectatic (NB) Mycobacterium avium complex (MAC) pulmonary diseases that manifested as unilateral lung disease.We retrospectively identified 674 patients with NB MAC pulmonary disease (PD) who underwent serial CT studies from January 2005 through December 2012. We selected patients with unilateral lung involvement as its initial manifestation. Retrospective analyses on serial CT findings in terms of presence and extent of lung abnormalities were performed. The organism identified (M. avium vs M. intracellulare) and treatment status were reviewed. To find the factors related to progression to involve both lungs, Cox regression analysis was performed.Unilateral MAC PD on initial CT was found in 47 patients (7%). Among them, 10 (21%) showed disease progression on follow-up CT to involve both lungs (mean evolving time, 1536 days). All 10 of these cases initially involved the right lung. Of these 10 patients, eight needed antibiotic treatment because of deteriorating imaging findings (4/8, 50%) or worsening symptoms (4/8, 50%). Initial total CT score (hazard ratio [HR], 1.414; 95% CI, 1.092-1.831; p0.01) and age (HR, 1.076; 95% CI, 1.004-1.154; p0.05) were related factors for disease progression in simple Cox regression test.Unilateral lung involvement of NB MAC PD is an occasional (7%) manifestation, and disease progressed in approximately 20% of patients in our study to involve both lungs. The imaging factor most related to disease progression appears to disease extent on initial CT.

The purpose of this study is to determine the imaging-based parameters associated with the occurrence of persistent type II endoleaks after endovascular abdominal aortic aneurysm repair.We reviewed the imaging and clinical data for 47 patients with early-onset type II endoleak after endovascular repair. Various predictors of persistent type II endoleaks were analyzed on the basis of preoperative CT findings. In addition, the appearance time of endoleak cavity on the operative angiogram and the relative attenuation of the endoleak cavity in the arterial phase image from the first postoperative CT study were analyzed.The early-onset type II endoleak resolved spontaneously in 22 patients (i.e., the transient group), whereas it was identified on CT studies of the remaining 25 patients 6 months after endovascular repair (i.e., the persistent group). The appearance time of the endoleak cavity on angiographic examination was significantly shorter in the persistent group than in the transient group (mean [± SD] appearance time, 4.7 ± 0.3 s vs 8.8 ± 0.3 s). The relative attenuation of the endoleak cavity on the first postoperative CT scan was also significantly higher in the persistent group than in the transient group (mean, 0.70 ± 0.03 vs 0.30 ± 0.04). For each parameter, ROC analysis revealed the following cutoff points for predicting persistent type II endoleak: 6 seconds for the appearance time of the endoleak cavity (sensitivity, 88%; specificity, 86%), and 0.5 for the relative attenuation of the endoleak cavity (sensitivity, 80%; specificity, 95%). Evaluation of other imaging-based parameters revealed no statistically significant differences between the groups.The appearance time of the endoleak cavity on the final operative angiogram and the attenuation of the endoleak cavity on the first postoperative CT scan can be strong imaging-based predictors of persistent type II endoleak.

OBJECTIVE: The objective of this study was to systematically evaluate the accuracy of abdominal CT performed at different radiation dose levels for the detection of body packs in human cadavers, in comparison with the accuracy of abdominal radiography. MATERIALS AND METHODS: In this study, differing numbers of body packs (range, 0-20) were placed in the alimentary tract of human cadavers and then underwent imaging with abdominal radiography and with CT performed at different radiation dose levels (ranging from the standard abdominal CT dose to the technical minimum dose). Depiction of body packs on abdominal radiographs and on each CT scan was assessed by two independent blinded radiologists, and the accuracy of detection of body packs was calculated. The radiation dose associated with abdominal radiography was measured, and the effective radiation dose associated with CT was estimated. RESULTS: The mean (± SD) effective radiation dose for abdominal radiography was 1.4 ± 0.3 mSv, whereas the mean effective dose of CT ranged from 0.1 to 9.6 mSv. Interobserver agreement for body pack detection was moderate (κ = 0.51) for abdominal radiography and good (κ = 0.72-0.85) for CT. In a per-body pack analysis, abdominal radiography depicted 42% of the body packs with a sensitivity of 71% and a specificity of 100%. When performed at radiation dose levels of 0.6 mSv or greater, CT correctly detected all body packs. In per-person analysis, the sensitivity and specificity of CT for the correct detection of at least one body pack per cadaver was 100% for all radiation dose levels. CONCLUSION: CT performed at a dose of 0.6 mSv can be used for the detection of body packs. With a sensitivity and specificity of 100%, CT is superior to abdominal radiography in terms of reliability, associated radiation dose, and accuracy of detection.

The objective of our study was to quantitatively compare misregistration in selected abdominopelvic organs between PET/CT acquisitions and simultaneous and sequential PET/MRI acquisitions.PET/MR images of 15 healthy volunteers and seven patients with bladder cancer were acquired. Ten clinical PET/CT studies acquired during the same time frame of body mass index-matched control subjects were chosen. PET/MRI and PET/CT registration of selected abdominopelvic organs was measured and compared.The overall mean misregistration with PET/MRI was significantly higher than that with PET/CT (p0.001). Sequential PET/MRI acquisition was significantly inferior to PET/CT (p = 0.02), whereas there was no significant difference between simultaneous PET/MRI acquisition and PET/CT (p = 0.38). Simultaneous PET/MRI acquisition was significantly better than sequential PET/MRI acquisition (p0.001). The mean misregistration for all organs with the T1-weighted volumetric interpolated breath-hold examination (VIBE) sequence (2.39 cm) was significantly inferior to PET/CT (p0.001). Although the T2-weighted HASTE breath-hold sequence was significantly inferior to PET/CT (p = 0.04), the T2 HASTE non-breath-hold sequence and T2 STIR sequence (0.18 cm) were significantly superior to both PET/CT and the T1 VIBE sequence (p0.001). Within the same sequence (T1 VIBE breath-hold sequence), the mean misregistrations with sequential and simultaneous PET/MRI acquisitions were both significantly greater than with PET/CT (p0.001), whereas simultaneous PET/MRI acquisition was superior to sequential PET/MRI acquisition (p0.001).In the abdominopelvic organs, sequentially obtained PET/MRI data have significantly higher misregistration than both PET/CT data and simultaneously acquired PET/MRI data. Simultaneously obtained PET/MRI data are statistically noninferior to PET/CT. Nonradial T1 VIBE has the highest misregistration, whereas T2 STIR and T2 HASTE non-breath-hold are significantly better than both PET/CT and T1 VIBE.

Despite a recent focus on the preferential use of ultrasound over CT for pediatric appendicitis, most children transferred from community hospitals still undergo diagnostic CT scans. The purpose of this study was to evaluate CT techniques performed for children with acute appendicitis at nonpediatric treatment centers.All patients treated for acute appendicitis at our tertiary-care pediatric hospital from July 1, 2011, through June 30, 2012, were identified. Patient demographics, imaging modality used to diagnoses appendicitis (CT or ultrasound), location (home or referral institution), and CT technique parameters were collected. The estimated mean organ radiation dose, number of imaging phases, and use of contrast media were evaluated at home and referral institutions.During the study period, 1215 patients underwent appendectomies after imaging, with 442 (36.4%) imaged at referral facilities. Most referral patients received a diagnosis by CT (n=384, 87%), compared with 73 of 773 (9.4%) who received a diagnosis by CT at the home institution. The estimated mean (±SD) organ radiation dose was not statistically significantly different between home and referral institutions (13.5±7.3 vs 12.9±6.4 mGy; p=0.58) for single-phase examinations. Of 384 referral patients, 344 had images available for review. In total, 40% (138/344) of patients from referral centers were imaged with suboptimal CT techniques: 50 delayed phase only, 52 dual phase (eight of which were imaged twice in delayed phase), eight triple phase, and 36 without IV contrast agent.CT parameters and radiation doses from single-phase examinations in children with appendicitis were similar at nonpediatric treatment centers and a tertiary care children's hospital. Future educational outreach should focus on optimizing other technical parameters.

OBJECTIVE. Lifelong postprocedural imaging surveillance is necessary after endovascular abdominal aortic aneurysm repair (EVAR) to assess for complications of endograft placement, as well as device failure and continued aneurysm growth. Refinement of the surveillance CT technique and development of ultrasound and MRI protocols are important to limit radiation exposure. CONCLUSION. A comprehensive understanding of EVAR surveillance is necessary to identify life-threatening complications and to aid in secondary treatment planning.

OBJECTIVE. Medical radiation–induced cataracts, especially those resulting from head and neck CT studies, are an issue of concern. The current study aimed to determine the risk of cataract associated with repeated radiation exposure from head and neck CT. MATERIALS AND METHODS. This study used information from a random sample of 2 million persons enrolled in the nationally representative Taiwan National Health Insurance Research Database. Exposed cases consisted of patients with head and neck tumor 10– 50 years old who underwent at least one CT between 2000 and 2009. The nonexposed control group was composed of subjects who were never exposed to CT studies but who were matched by time of enrollment, age, sex, history of coronary artery disease, hypertension, and diabetes. RESULTS. There were 2776 patients in the exposed group and 27,761 matched subjects in the nonexposed group. The exposed group had higher overall incidence of cataracts (0.97% vs 0.72%; adjusted hazard ratio [HR], 1.76; 95% CI, 1.18–2.63). Further stratifying the number of CT studies in the exposed group into one or two, three or four, and five or more revealed that cataract incidence increased gradually with increasing frequency of CT studies (0.79%, 0.93%, and 1.45%, respectively) (p = 0.001, adjusted for trend). Radiation exposure due to repeated head and neck CT studies was independently associated with an increased risk of developing cataracts when the cumulative CT exposure frequency involved more than four studies (adjusted HR, 2.12; 95% CI, 1.09–4.14). CONCLUSION. Repeated exposure to head and neck CT is significantly associated with increased risk of cataract.

The purpose of this study is to investigate emergency department (ED) providers' knowledge of the lifetime cancer risk attributable to radiation from commonly performed CT scans and its association with the ordering providers' risk-benefit analysis before ordering the examination. This study further explores factors that may influence a provider's selection of a particular diagnostic imaging study in an ED setting.Sixty-seven ED providers at the University of Rochester Medical Center completed a multiple-choice questionnaire. The questions were derived to assess an individual provider's awareness of lifetime cancer risk attributable to radiation from a diagnostic CT scan of the abdomen or pelvis and the provider's behavior toward risk-benefit analysis before ordering the examination. The association between the questions and years since completion of clinical training was determined using the Spearman correlation test. Univariate logistic regression analysis was used for the same questions to predict the knowledge of lifetime cancer risk attributable to radiation.Fewer than 30% of ED providers possessed accurate knowledge of lifetime cancer risk attributable to radiation (p = 0.025). Providers with greater clinical experience, although lacking in the knowledge of lifetime cancer risk attributable to radiation, were more likely to consider patients' radiation dose history and to conduct a risk-benefit analysis and were less likely to order a CT scan unnecessarily. Clinical experience was negatively correlated with perceived unnecessary use of CT scans (p = 0.01).A large proportion of ED providers are unaware of the lifetime risk of carcinogenesis associated with commonly performed CT scans. Clinical experience, not knowledge of lifetime cancer risk attributable to radiation, is significantly associated with beneficial behavior toward the use of CT.

Radiation exposure from CT studies has increased over the past 30 years in the United States and now constitutes approximately 50% of the radiation dose index administered in the health care setting. Tracking CT dose index (CTDI) is cumbersome because it relies on a manufacturer-generated screen capture, which contains the estimated dose index exposure for the patient. The radiation dose index information is not digital but, rather, is "burned" into the image (i.e., not in numeric form, not as part of the image header or elsewhere associated with the study), making it difficult to automatically share these data with other information systems. The purpose of the dose index reporting application (DIRA) we developed for CT is to extract the radiation dose index information from the CTDI reports to eventually perform automated quality control, promote radiation safety awareness, and provide a longitudinal record of patient-specific health care-related radiation exposure.A random selection of 518 CTDI reports were processed by the DIRA and the dose index information was extracted. CTDI reports using a standard DICOM C-STORE to the DIRA allow an automated process to compile radiation dose index and patient information in a Web-based framework using a structured query language (SQL) database.Our initial tests showed that the DIRA accurately extracted dose index information from 518 of 518 CTDI reports (100%). Because the extracted CTDI descriptor-dose-length product-is based on standard CTDI measurements obtained using fixed-size cylindric polymethylmethacrylate phantoms, preliminary studies have been performed to correct for patient size by applying correction factors derived from CTDI measurements using a range of phantom sizes from 6 to 32 cm in diameter. Our system provides a way to automatically track CTDI on existing CT scanners and does not rely on the DICOM SR Dose Index Report standard, which is available on only the newest CT scanners.A modular and vendor-independent DIRA system can be integrated with any existing CT scanner. This system greatly facilitates digital dose index reporting and makes it possible to provide a longitudinal record of the health care radiation exposure estimate in an individual patient's health record.

OBJECTIVE. The purpose of this study was to use MDCT to examine two mummies found in the tomb of King Tutankhamun to estimate their gestational ages at mummification, to determine the mummification method, and to investigate the congenital deformities of one of the mummies that had been suspected at previous medical examinations. MATERIALS AND METHODS. MDCT was performed on the mummies of the daughters of King Tutankhamun (article numbers 317a and 317b), and the images were reconstructed and subjected to forensic imaging analysis. RESULTS. The gestational ages at mummification of mummies 317a and 317b were estimated to be approximately 24.7 and 36.78 weeks. The skeletal congenital anomalies of mummy 317b suggested at past radiographic analysis were ruled out. CONCLUSION. The results of this study may set a precedent for use of CT and forensic image analysis in the study of ancient mummified fetuses.

Performing true whole-body FDG PET/CT is standard practice in pediatric lymphoma staging and follow-up. In adults, imaging is typically limited whole-body PET/CT, which has advantages over true whole-body PET/CT, primarily decreased scanning time and decreased radiation. We hypothesize that in pediatric lymphoma, limited whole-body PET/CT is sufficient for routine follow-up when disease on the true whole-body staging study is confined to the limited whole-body field of view (FOV).True whole-body PET/CT studies performed for staging and follow-up of pediatric lymphoma patients between November 2004 and July 2009 at two tertiary pediatric referral hospitals were retrospectively reviewed. Abnormalities on the limited whole-body and additional true whole-body FOV were documented.One hundred seventy patients met the inclusion criteria (752 examinations). At staging, disease involved the limited whole-body FOV without involving the additional true whole-body FOV in 150. Of the 150, 145 had routine follow-up (508 examinations). In these patients, no new (18)F-FDG-avid disease was identified outside of the limited whole-body FOV on routine follow-up (positive predictive value, 0%, 95% CI, 0-0.02).The limited whole-body PET/CT for routine follow-up when disease is confined to the limited whole-body FOV at staging is appropriate. Given its definite advantages over true whole-body PET/CT, it is preferred.

OBJECTIVE. In this part one of a two-part article, we aim to illustrate our understanding of and approach to comprehensive cardiac CT reporting, cardiac CT technique, and coronary calcium scoring CT, as well as normal and anomalous coronary artery anatomy.CONCLUSION. Structured cardiac CT reporting is important to effectively communicate with referring clinicians. Knowledge of cardiac CT technique, cardiac anatomy, and standard anatomic and physiologic terminology can assist the reader in creating a consistent and comprehensive cardiac CT report.

OBJECTIVE. Imaging of the vast array of pathologic processes occurring in the small bowel has been facilitated by recent advances, including the use of MDCT scanners that acquire isotropic data and neutral oral contrast agents that improve small-bowel distention.CONCLUSION. This review shows how a systematic pattern approach can be used to narrow the differential diagnosis when an abnormal small-bowel loop is detected on MDCT.

The purpose of our study was to evaluate the effects of 0.3-second high-resolution CT (HRCT) of the lung using partial reconstruction on cardiac motion artifacts and image noise.Thirty-seven pairs of 0.3-second (partial reconstruction) and 0.75-second (full reconstruction) HRCT images were obtained for the lower lung zone during full-inspiration breath-holding. Imaging parameters other than temporal resolution were identical for each patient. Two radiologists visually graded motion artifacts of the cardiac border, bronchi, pulmonary vessels, and fissure in the left lung on a 4-point scale (with 4 indicating no artifacts). The maximum width of motion along the left cardiac border and the area percentage of motion artifacts in the left lung were calculated. Image noise in the air and lung was also determined. Cardiac motion artifacts and image noises were compared between the two sets of CT images.Visual grades for the cardiac border (4 +/- 0), bronchi (3.8 +/- 0.7), pulmonary vessels (3.6 +/- 0.8), and fissure (3.9 +/- 0.5) were higher for 0.3-second images than for 0.75-second images (1.7 +/- 0.7, 2.0 +/- 1.0, 1.6 +/- 0.7, and 2.4 +/- 0.9, respectively) (p0.001). The maximum width of motion along the left cardiac border (0.1 +/- 0.5 mm) and the area percentage of motion artifacts in the left lung (6.7% +/- 18.4%) were smaller for 0.3-second images than for 0.75-second images (4.5 +/- 1.7 mm and 36.2% +/- 20.9%, respectively) (p0.001). Image noises in the air (38.0 +/- 9.2) and the lung (86.0 +/- 23.1) were greater for 0.3-second images than for 0.75-second images (35.6 +/- 9.6 and 76.0 +/- 20.3, respectively) (p0.01).Compared with 0.75-second HRCT using full reconstruction, 0.3-second HRCT using partial reconstruction substantially reduces cardiac motion artifacts in the lung at the expense of increasing image noise.

The purpose of this study was to define the optimal scan window for acquiring arterial phase images in the detection of hypervascular hepatocellular carcinomas (HCCs).Biphasic arterial phase CT examinations were performed using a 16-MDCT scanner on 198 patients (159 men and 39 women; mean age, 59 years; age range, 25-82 years) with nodular HCC. All examinations were performed after administering 120-150 mL of a nonionic contrast media (370 mg I/mL) at a rate of 3-4 mL/s. The scan delay--the interval between when the bolus-tracking program detected the threshold enhancement of 100 H in the abdominal aorta and the start of the first arterial scan-was progressively lengthened by 2-second intervals, from 10 seconds in group 1 to 20 seconds in group 6. The second arterial phase scan was started 6 seconds after the end of the early scan. A tube collimation of 1.5 mm, a table feed of 18 mm per rotation, an image thickness of 3 mm, and 3-mm increments were used. The duration of each phase scan was 4.5-8.8 seconds. Tumor-to-liver attenuation difference (TLAD) at the first (TLAD1) and second (TLAD2) arterial phase images were compared lesion by lesion. Four observers assigned subjective ratings of visual conspicuity and individual preferences for each phase in each group.The mean threshold time (100 H) was 18.4 +/- 3.1 seconds, and 97% of patients were within the range of 13-24 seconds. The mean TLAD1 of groups 3 to 6 and the mean TLAD2 of groups 1 to 5 were all comparable; they were also all significantly (p0.005) higher than the mean TLAD1 of groups 1 and 2 and the mean TLAD2 of group 6. In groups 1 and 2, the mean TLAD2 was significantly higher than the mean TLAD1 (p0.001); in groups 5 and 6, the mean TLAD1 was significantly higher than the mean TLAD2 (p0.001). In groups 3 and 4, the mean TLAD1 and TLAD2 were similar. The visual conspicuity and individual preferences were higher for the first-phase image in groups 3 to 6 and the second-phase image in groups 1 and 2.The optimal scan window for arterial phase images in the detection of HCC seems to be approximately 14-30 seconds from the 100-H threshold.

The objective of our study was to evaluate repeatability and reproducibility of lung nodule volume measurements using volumetric nodule-sizing software.Fifty nodules, less than 20 mm in diameter, in 29 patients were scanned with 1.25-mm collimation using MDCT (time 1 = T1). During the same session, two additional scans, using identical technique, were obtained through each nodule (T2, T3). Three observers working independently then obtained volumetric measurements using a semiautomated volumetric nodule-sizing software package. Qualitative nodule characterization was also performed. The Bland-Altman method for assessing measurement agreement was used to calculate the 95% limits for agreement for nodule volumes at T1, T2, and T3.Automated nodule segmentation was successful in 438 (97%) of 450 measurements. Forty-three nodules were available for final evaluation. Twenty-six nodules had well-defined edges, and 17 had irregular or spiculated margins. Seventeen were freestanding, 16 were juxtapleural, and 10 were juxtavascular in location. Average nodule volume was 345.5 mm(3) (range, 49.3-1,434 mm(3)). The mean interobserver variability (repeatability) was 0.018% (SD = 0.73%), and the SD of the mean for the three contemporaneous scans (reproducibility) was 13.1% (confidence limits, +/- 25.6%). SD and confidence limits narrowed as volumes increased.Volumetric measurements show minimal interobserver variability (0.018%) but an interscan SEM of 13.1% (confidence limits, +/- 25.6%). Repeatability and reproducibility of volumetric measurements are better than those of linear measurements reported in the literature.

OBJECTIVE. CT accounts for considerable population-based radiation dose from radiographic diagnostic studies. The technical factors for CT examinations are not appropriately adjusted on the basis of patient size and anatomy. We hypothesized that radiation doses for routine chest CT can be reduced by 50% for the evaluation of normal structures without seriously jeopardizing image quality.SUBJECTS AND METHODS. After receiving institutional review board approval, we prospectively studied 24 patients with cancer who were 65 years old and older on a multidetector CT scanner. Each patient underwent imaging with four slices (centered at the carina) at the standard dose (220-280 mAs) and at 50%—reduced dose (110-140 mAs) at a constant 140 kVp. Single breath-hold scanning was performed with a 2.5-mm detector configuration, a tube rotation time of 0.8 sec, and a pitch of 6:1. Contiguous images were reconstructed at 5-mm intervals. Two subspecialty-trained chest radiologists who were unaware of the CT technique revi...

CT technique should be adjusted while scanning infants and children. One format that has proven successful in simplifying pediatric care and reducing medical error is the size-based, color-coded Broselow-Luten pediatric system. This color-coded system can serve as a format for CT protocols. The purpose of this investigation was to compare variation (or error) occurrence and technologist preference for conventional and color-coded formats for pediatric multidetector body CT protocols.Multidetector CT examinations were set up using either a conventional or a color-coded format for a period of 6 weeks each. Variations (errors) from protocol parameters (including tube current, detector configuration, table speed, and IV contrast media dose) were tabulated. Qualitative assessment consisted of a survey of CT technologists (n = 20) for preference in six areas related to ease of use and clarity of the formats.There were 44 CT examinations (n = 30 infants and children) in the conventional group and 55 CT examinations (n = 31 infants and children) in the color-coded protocol format group. Overall, the number of errors was significantly less in the color-coded group (p0.01), with a significantly lower error percentage in individual parameters affecting radiation dose, including tube current, detector configuration, and table speed (p0.05). In all areas, the color-coded format was preferred over the conventional format (p0.0003).Color-coded CT formatting is an extension of a clinical color-coded system. This system provides an easy, expeditious, consistent, and preferable format for general pediatric body CT protocols. Most importantly, the color-coded system can reduce variations (errors) in the radiology department.

The extravasation detection accessory (EDA) is designed for use during contrast-enhanced CT studies performed with a power injector. The EDA detects the changes in soft-tissue impedance that occur with enhanced extravasation and halts the further infusion of contrast material via a feedback circuit to the injector. We tested the sensitivity of this device in a model of contrast extravasation.Study subjects had an extravasation of 5% dextrose in water (nonionic contrast equivalent) in one arm and 0.9% sodium chloride solution (ionic contrast equivalent) in the other. An EDA was placed over the site of infusion and connected to a power injector. Injections were performed at 0.25 ml/sec (n = 40), 2.5 ml/sec (n = 62), or 5 ml/sec (n = 20).At infusion rates of 2.5 and 5 ml/sec, the device halted the injector in every subject after an average volume of 12.5 +/- 1.6 ml was delivered. At 0.25 ml/sec, the device failed to halt the injector in 11 of 20 events. After reprogramming the algorithm, 10 more subjects were tested at the lowest injection rate. The device halted 18 of 20 extravasation events with an average volume of 3.7 +/- 0.5 ml.In our model of contrast extravasation, the EDA halted a power injector with reliability and reproducibility before a large volume of contrast material was delivered. The sensitivity of the device approached, but did not reach, 100%. This device may serve to diminish the morbidity of extravasation events.

When a stone is located in the region of the ureterovesical junction on CT studies, it is important to determine if the stone is impacted at the ureterovesical junction or has already passed into the bladder. The purpose of this study was to determine if CT findings can be used to distinguish stones impacted at the ureterovesical junction from stones that have already passed into the bladder.From February 1, 1997, to January 31, 1998, 37 patients with acute flank pain underwent unenhanced CT studies in the supine position that showed stones in the region of the ureterovesical junction. To determine stone location, limited rescans were obtained with the patients in the prone position. The supine images were reviewed retrospectively by one of the authors, who was unaware of the findings of the prone scans. Forty-one stones were classified as being impacted at the ureterovesical junction or as having passed into the bladder.On CT, 23 stones were correctly classified as being impacted at the ureterovesical junction; nine stones were correctly classified as having passed into the bladder; and nine stones were incorrectly classified as being within the bladder. We calculated a sensitivity of 72%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 50%, and an accuracy of 78% for CT in revealing stones impacted at the ureterovesical junction.If patients are imaged in the supine position only, unenhanced helical CT cannot reliably distinguish stones impacted at the ureterovesical junction from stones that have already passed into the bladder. A prone scan can be used to make this distinction.

This investigation analyzed the potential impact on hospitalwide variable costs and total costs of introducing a focused helical CT technique for diagnosing appendicitis.This investigation had three components. First, we retrospectively reviewed the records of 651 patients who had admitting diagnoses of appendicitis. Second, we determined variable costs and total costs for the components of these patients' care. Third, we projected change in costs if the focused appendiceal CT technique had been used to guide patient management.Using focused appendiceal CT in 100 patients would have decreased the number of nontherapeutic appendectomies by 13. The average length of stay for observation would have also decreased by 1 day because the diagnosis of an abnormal appendix or an alternative diagnosis would have been made more quickly. Savings in variable costs and total costs would have been $23,030 and $45,556 per 100 patients, respectively.Routine use of focused appendiceal CT would lower the costs of caring for patients with clinically suspected appendicitis.

OBJECTIVE. A review was made of the CT studies and pathology reports of four patients with surgically resected colonic villous adenomatous tumors, two of whom had focal carcinomatous invasion.CONCLUSION. Two patients had villous tumors with IV contrast-enhancing convolutional gyral patterns. The other two patients had tumor masses that showed oral contrast medium collecting in surface interstices, analogous to findings with barium enemas. One of the latter also had an unusual cluster of mesenteric vessels adjacent to the lesion.

This essay illustrates the appearance of the traumatized spleen on CT scans obtained during the course of conservative treatment. Although the CT appearance of acute rupture of the spleen has been adequately described, little has been reported about the appearance of the spleen as it heals after trauma. Examples of CT studies of splenic injuries illustrate the various changes in appearance over time in the traumatized spleen that is treated nonoperatively.

Serial barium and CT studies were performed for follow-up of 35 patients who had undergone transhiatal esophagectomy with gastric interposition for esophageal carcinoma. The results were compared with the clinical and pathologic findings. Thirteen patients (37%) were clinically and radiologically free of tumor recurrence after a mean observation period of 18 months. Twenty-one patients (60%) developed recurrent carcinoma within 12 months and one patient (3%) within 14 months. Thirteen patients were clinically asymptomatic when recurrence was detected radiologically. Recurrence was initially confined to the mediastinum in one-half of the patients, whereas the others already had distant metastases when recurrence first became evident. Because most of the recurrent lesions originated outside the interposed stomach, CT was more useful than barium studies in showing early recurrence. Radiologic follow-up including CT allows earlier detection of limited recurrent carcinoma after surgery and, thus, offers the possibility of appropriate additional palliative radiotherapy or chemotherapy.

Magnetic resonance (MR) imaging of the orbit was performed with a 0.6 T superconducting imaging system in 100 patients with normal orbits who were being evaluated for brain pathology and in 21 additional patients with a variety of orbital lesions to determine the efficacy of MR imaging in displaying orbital abnormalities. Usually, MR studies were performed using a multislice technique with multiple spin-echo pulse sequences and 30, 60, and 90 msec echo times and 500, 1500, and 2000 msec repetition times. Using section thicknesses of about 8 mm, imaging was performed in the transaxial, coronal, and sagittal projections. Pixel size was 0.9 × 1.8 mm, and the examination took about 30 min. The MR findings were compared with computed tomographic (CT) findings in all cases. Either combined axial and coronal studies of 5-mm-thick sections or a thin axial study of 1-mm-thick sections followed by reformatting techniques to obtain multiplanar images was used. Contrast enhancement was used in the CT studies. Both MR and CT clearly demonstrated the soft-tissue abnormality in all cases except two, in which MR failed to detect the abnormality. In one, MR failed to detect a small retrobulbar hemorrhage that occurred after a surgical procedure for retinal detachment. In the second case, rather extensive calcification in the posterior choroidal layers and lens was not detected by MR imaging. In several other cases, MR provided information beyond that obtained with CT. MR has the advantage of providing exquisite anatomic detail in multiplanar images, and it appears to be more sensitive than CT in detecting small, subacute and chronic hemorrhage within soft-tissue masses in the orbit and in detecting ischemia of the globe. CT is superior to MR imaging in portraying fine bone detail.

Physicians who monitor cranial computed tomography occasionally omit the most superior aspects of the brain and calvarium because of time limitations and overloaded scanning schedules. In addition, standardized CT reporting forms as well training literature distributed by some manufacturers support the concept that a complete CT series consists of three scan pairs. Omission of a vertex scan pair results in failure to visualize 10%-15% of the brain volume. We have reviewed the results of 2,000 consecutive CT studies to determine the number and variety of pathologic entities that would have been missed had a vertex scan not been obtained. The most significant or sole abnormality was present on the vertex scan alone in 3% of the cases. Examples are presented. A true vertex levels should be obtained in every routine CT examination.

Eighteen CT examinations of the wrist were performed in 13 patients to evaluate the results of treatment for carpal fractures. In four cases with metal objects and in seven with cast materials, there was no difficulty achieving adequate CT studies. In 13 cases CT was found to be helpful in determining bony union in the presence of advanced osteoporosis. In six cases CT was excellent in evaluating bone-graft incorporation. CT affords improved detection of fractures perpendicular to the plane of the scan and also shows small areas of bone disruption, even with osteoporosis. Axial CT images can evaluate Lister's tubercle, a bony prominence on the dorsum of the distal radius, for hypertrophy, which can occur secondary to traumatic and degenerative changes. A hypertrophied tubercle can impinge on the extensor pollicis longus tendon and cause atrophy and disruption. The high cost of CT is offset by the possibility of reducing the patient's period of immobilization and, thereby, the length of time the patient is unable to participate in normal activities. In addition, since CT is often definitive, the number of supplemental or follow-up radiologic procedures or clinical appointments should be reduced. We conclude that CT is useful in evaluating the results of treatment of wrist injuries.

One hundred and two follow-up CT studies in 50 patients with a diagnosis of lymphoma were reviewed to determine the efficacy of limited CT studies for determining therapy. The overall correlation between the limited CT study and the complete CT study was 98%. No mixed responses occurred in 102 cases. Two patients, both with diffuse histocytic lymphoma treated by chemotherapy, showed progression of disease outside a stable tumor bed not detected by a limited CT study. The economic implications, technique, and limitations of limited CT studies are presented.

Little is known about the significance of one or more septations within a renal cyst. The records of 26 patients whose sonographic and/or CT studies showed evidence of internal septations were reviewed to assess their significance. Thirteen patients underwent surgical exploration; in 10, the final diagnoses were benign lesions, while in three there were elements of renal cell carcinoma. Criteria are suggested to distinguish benign from malignant lesions. One or more thin septations alone is probably of no clinical significance, but if there are solid elements demonstrated, further evaluation is mandatory.