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A novel traceable point-like 68Ge/68Ga source was developed for calibration of positron emission tomography (PET) scanners. The source was equipped with a spherically symmetric acrylic positron absorber. The physical characteristics of photons emitted from the point-like source were evaluated by Monte Carlo simulation, considering possible geometrical uncertainties. The calibration factor of a clinical PET/CT scanner was evaluated using four manufactured point-like sources as a practical application of the point-like source. The results were consistent with that determined by the conventional cross-calibration method. The traceable point-like 68Ge/68Ga source is expected to be a simple and practical tool for determining the calibration factor and evaluating the physical characteristics of PET scanners.

Preoperative identification of the artery of Adamkiewicz can help prevent postoperative spinal cord injury following thoracic and thoracoabdominal aortic repair. Several studies have demonstrated the feasibility of evaluating the artery of Adamkiewicz using multi-detector row computed tomography (CT), but precise visualization remains a challenge. The present study was conducted to evaluate the usefulness of ultra-high-resolution CT for visualizing the artery of Adamkiewicz with a slice thickness of 0.25 versus 0.5 mm in patients with aortic aneurysms. Our institutional review board approved this study. Twenty-four patients with thoracic and thoracoabdominal aneurysms were scanned with beam collimation of 0.25 mm × 128. Images were reconstructed with slice thicknesses of 0.25 and 0.5 mm. The signal-to-noise ratio (SNR) of the aorta and contrast-to-noise ratio (CNR) between the anterior spinal artery and spinal cord were measured. Two independent observers evaluated visualization of the artery of Adamkiewicz and its continuity between the anterior spinal artery and the aorta using a four-point scale. No significant differences in the SNR of the aorta or CNR of the anterior spinal artery were observed between 0.25- and 0.5-mm slices. The average visualization score was significantly higher for 0.25-mm slices (3.58 ± 0.78) than for 0.5-mm slices (3.13 ± 0.99) (p = 0.01). The percentage of patients with nondiagnostic image quality was significantly lower for 0.25-mm slices (8.3%) than for 0.5-mm slices (33.3%) (p = 0.03). In patients with aortic aneurysms, ultra-high-resolution CT with 0.25-mm slices significantly improves visualization of the artery of Adamkiewicz compared to 0.5-mm slices.

Patient narratives of adverse drug events (ADEs) often differ from the symptoms listed on the package inserts of pharmaceutical products using common ADE terminology and could be a source of great comfort to patients with the same disease. To explore this idea, we analyzed written narratives obtained from 48 patients with breast cancer using the NPO Corporation Database of Individual Patients' Experiences, Japan (DIPEx-Japan). Our analysis aimed to determine the utility of an "Adverse Drug Event Database" for use in clinical settings as a novel source of disease information in patients' own words. An analysis of transcripts from 29 patients, in which they recounted their treatment drugs and the time of onset and duration of ADEs in great detail, revealed several discrepancies between the language they used to describe various side effects and the standard ADE terminology on package inserts. We conclude that the language used to describe ADEs on package inserts is insufficient for helping patients as they struggle to recognize, internalize, and overcome ADEs, and argue the need for available, detailed information in the words of real patients about the nature of the ADEs predicted, as well as their clinical course and duration. Such information would be invaluable in supplementing the standardized language used on package inserts. Databases of patients' narrative accounts of ADEs are needed as information sources that can be reliably disseminated among patients.

PURPOSE We conducted a field survey about pediatric nuclear medicine. As a result, it was suggested that 99mTc-DMSA scintigraphy was performed at many institutions, whereas various examinations such as image acquisition and processing are not carried out using the renal phantom. Therefore, we developed the body phantom for the evaluation of appropriate administered radioactivities and image quality with renal scintigraphy in pediatric nuclear medicine. METHODS We created three differently sized body phantoms (1-, 5-, and 20-year-old models). These pediatric body phantoms were filled with a 99mTc solution based on the consensus guideline of pediatric radiopharmaceutical administered radioactivity in Japan. The planar image was evaluated using acquisition count, uniformity and defect contrast. SPECT images were evaluated with a recovery coefficient (RC). RESULTS The acquisition counts for pediatric body phantoms were relatively corresponded to the clinical study. The appropriate acquisition counts and the pixel size for the planar image were approximately 140 counts per pixel and 1.23-1.35 mm at 5 min acquisition times in 1- and 5-year-old pediatric body phantom studies, respectively. Although the uniformity and the cold contrast did not depend on pixel size and body size, the cold contrast was affected by body size. The RC for SPECT images depended on the performance of SPECT systems, the resolution recovery algorithm and body phantom size. CONCLUSION The developed pediatric body phantom could allow us to establish optimal image acquisition and more evidence on renal scintigraphy in pediatric nuclear medicine.

Rationale and Objectives Severe calcifications of the coronary arteries are still a major challenge in coronary computed tomography (CT) angiography (CCTA). Subtraction CCTA using a 320-detector row CT scanner has recently been introduced for patients with severe calcifications. However, the conventional subtraction CCTA method requires a long breath-holding time of approximately 20–40 seconds. This is a major problem in clinical practice because many patients may not be able to perform such a long breath-hold. We explored a modified subtraction CCTA method with a short breath-holding time to overcome this problem. Materials and Methods This study was approved by our institutional review board, and all patients gave written informed consent. A total of 12 patients with a coronary calcium score of >400 were enrolled in this study. All patients were unable to hold their breath for more than 20 seconds. Modified subtraction CCTA was performed using the bolus-tracking method. The acquisition protocol was adjusted so that the mask scan was acquired 10 seconds after the postcontrast scan during a single breath-hold. The subtraction image was obtained by subtracting the mask image data from the postcontrast image data. The breath-holding times were recorded. Enhancement of the coronary arteries in the subtraction images was assessed. Subjective image quality was evaluated in a total of 32 segments using a 4-point scale. Results The mean breath-holding time was 12.8 ± 0.8 seconds (range, 12–14 seconds). The average CT number in the coronary arteries was 288.6 ± 80.5 Hounsfield units (HU) in the subtraction images. Average image quality was significantly increased from 2.1 ± 0.9 with conventional CCTA to 3.1 ± 0.7 with subtraction CCTA ( P P = 0.001). Conclusions This preliminary study has shown that our modified subtraction CCTA method allows the breath-holding time to be shortened to

Septal penetration causes collimator-dependent differences in the heart-to-mediastinum (H/M) ratio in 123I-metaiodobenzylguanidine (MIBG) cardiac imaging. We investigated generally applicable methods to correct such differences. Four hours after 123I-MIBG injection, 40 patients underwent anterior chest imaging successively with medium-energy (ME) and various non-ME collimators. The H/M ratios obtained with the non-ME collimators before and after 123I-dual-window penetration correction were compared with the ME-derived standard values to determine patient-based conversion equations for empiric and combined corrections, respectively. A 123I point source was imaged with various collimators, and the central ratio, the ratio of count in a small central region of interest to count in a large one, was calculated. The method of predicting the conversion equations from the central ratios was determined. Correction using the patient-based conversion equations removed systematic underestimation of the H/M ratios obtained with the non-ME collimators, and combined correction depressed residual random errors to some degree. Point-source-based equations yielded results comparable to the patient-based equations. Empiric and combined corrections effectively reduce collimator-dependent differences in the H/M ratio. The conversion equations can be predicted from simple point-source imaging, which would allow to apply these corrections to data obtained with various collimators.

Most of hemiplegic subjects need foot drop correction in order to decrease the risk of falling during walking. Since compensatory movements such as circumduction and steppage gait are considered to be developed to achieve foot clearance in the swing phase, such movements might be improved if enough ankle dorsiflexion is developed in the swing phase. In this paper, hip joint and ankle joint angles of a hemiplegic subject were measured during walking with inertial sensors, when FES foot drop correction was applied. As the ankle dorsiflexion angle decreased by muscle fatigue, hip flexion angle begun to increase earlier and timings of the heel off and the toe off were detected earlier, which were similar to gait movement of the subject without FES foot drop correction. These changes were considered to be a preparatory movement for achieving foot clearance by increasing hip flexion. This result suggested that the compensatory movements by the hip joint could be improved by FES foot drop correction.

The heart-to-mediastinum (H/M) ratio, the heart count normalized for the mediastinum count, is commonly used in cardiac (123)I-metaiodobenzylguanidine (MIBG) imaging. However, there are reports describing age-dependent increases in the mediastinum count with or without correction for the injected dose (ID) and a poor correlation between the H/M ratio and heart count normalized for ID. We evaluated the validity of the mediastinum count as a reference in comparison with the ID.Results of cardiac (123)I-MIBG imaging in 200 patients were analyzed. The mean counts for the heart and mediastinum were estimated to calculate the H/M ratio. Additionally, the heart and mediastinum counts were normalized for ID measured with a dose calibrator. ID was corrected for body size represented by body weight, body surface area, or lean body mass.The coefficient of variance of the ID-normalized mediastinum count was reduced by correcting ID for body size. The indicators of body size showed significant negative correlations with age. Although a positive correlation was found between age and the ID-normalized mediastinum counts, the age-dependence was reduced by body size correction. There was a close correlation between the H/M ratio and ID-normalized heart counts, and body size correction improved the correlation.The results of this study indicate the validity of the mediastinum as a reference region and support the use of the H/M ratio as an index of cardiac accumulation of (123)I-MIBG.

Septal penetration causes underestimation of the heart-to-mediastinum (H/M) ratio in cardiac (123)I-metaiodobenzylguanidine (MIBG) imaging with a low-energy high-resolution (LEHR) collimator. We aimed to improve the method of estimating the H/M ratios using the LEHR collimator.4 hours after (123)I-MIBG injection, 40 patients were imaged successively with the medium-energy (ME) and LEHR collimators using gamma cameras having 3/8-inch crystals. Severe underestimation of the H/M ratios was observed with the LEHR collimator when compared to the ME collimator. Narrowing the energy window width did not reduce the underestimation. Application of (123)I-dual-window (IDW) correction using a narrow or wide subwindow reduced the underestimation substantially but not entirely. The H/M ratios estimated from the LEHR images with or without IDW correction were corrected based on their correlations with the ratios estimated from the ME images. This empiric correction removed systematic underestimation, and residual errors were reduced when the H/M ratios after IDW correction were converted using the empiric equation. The conversion equation was successfully applied to the correction of the H/M ratios determined in another 40 patients using a 5/8-inch crystal.In estimating the H/M ratios using an LEHR collimator, empiric correction combined with IDW correction improves concordance with ME-based values in comparison with empiric correction alone.

Septal penetration of high-energy photons affects the estimation of the heart-to-mediastinum (H/M) ratio in cardiac (123)I-metaiodobenzylguanidine (MIBG) imaging, and the use of a medium-energy (ME) collimator has been shown to improve quantitative accuracy. We investigated the effect of septal penetration on the estimation of H/M ratios using an ME collimator.Point sources of (99m)Tc and (123)I were imaged using various collimators, which indicated that the effect of high-energy photons with the ME collimator was relatively small but larger than that with the high-energy (HE) collimator. Four hours after (123)I-MIBG injection, 20 patients underwent planar anterior chest imaging by different methods in succession. The ME collimator gave lower H/M ratios (mean 2.52) than the HE collimator (2.57), indicating influence of septal penetration in the ME collimator; however, the difference was limited. Although narrowing the energy window from 20% (2.51) to 15% (2.54) increased the H/M ratios in imaging with the ME collimator, the difference was quite limited.Septal penetration affects the estimation of the H/M ratios using an ME collimator; however, this influence is small and would not have clinical significance.

To improve the reliability and convenience of the calibration procedure of positron emission tomography (PET) scanners, we have been developing a novel calibration path based on traceable point-like sources. When using (22)Na sources, special care should be taken to avoid the effects of 1.275-MeV γ rays accompanying β (+) decays. The purpose of this study is to validate this new calibration scheme with traceable point-like (22)Na sources on various types of PET scanners.Traceable point-like (22)Na sources with a spherical absorber design that assures uniform angular distribution of the emitted annihilation photons were used. The tested PET scanners included a clinical whole-body PET scanner, four types of clinical PET/CT scanners from different manufacturers, and a small-animal PET scanner. The region of interest (ROI) diameter dependence of ROI values was represented with a fitting function, which was assumed to consist of a recovery part due to spatial resolution and a quadratic background part originating from the scattered γ rays.The observed ROI radius dependence was well represented with the assumed fitting function (R (2)0.994). The calibration factors determined using the point-like sources were consistent with those by the standard cross-calibration method within an uncertainty of ±4 %, which was reasonable considering the uncertainty in the standard cross-calibration method.This novel calibration scheme based on the use of traceable (22)Na point-like sources was successfully validated for six types of commercial PET scanners.

To explore the feasibility and diagnostic accuracy of modified subtraction coronary CT angiography (CCTA) with short breath-holding time in patients who have limited breath-hold capability and severe coronary artery calcification.11 patients with a coronary calcium score400 underwent CCTA using a modified subtraction protocol. All patients were unable to hold their breath for more than 20 s. Subjective image quality using a four-point scale and the presence of significant (50%) luminal stenosis were assessed for each calcified or stented segment on both conventional CCTA and modified subtraction CCTA images and compared with invasive coronary angiography (ICA) as the gold standard.The mean breath-holding time was 13.0 ± 0.9 s. A total of 35 calcified or stented coronary segments were evaluated. The average image quality was increased from 2.1 ± 0.9 with conventional CCTA to 3.1 ± 0.7 with subtraction CCTA (p 0.001). The segment-based diagnostic accuracy for detecting significant stenosis according to ICA revealed an area under the receiver-operating characteristic curve of 0.722 for conventional CCTA and 0.892 for subtraction CCTA (p = 0.036).Modified subtraction CCTA allows the breath-holding time to be shortened to15 s. As compared with conventional CCTA, modified subtraction CCTA showed improvement in image quality and diagnostic accuracy in patients with limited breath-hold capability and severe calcification.Modified subtraction CCTA can improve the diagnostic accuracy in patients with a high calcium score and patients who are unable to perform long breath-holds.

PURPOSE The present study aims to quantitatively investigate a normal database (NDB) created under the same acquisition and reconstruction conditions for three gamma camera systems (four types of collimator systems) with use of three-dimensional stereotactic surface projections (3D-SSP). We rebuilt a NDB with use of the N-isopropyl-p-(123)I-iodoamphetamine ((123)I-IMP) SPECT data derived from 30 healthy individuals at 20 institutions nationwide. We standardized the acquisition and reconstruction conditions, evaluated Z scores using patient data (PD) and examined each compensation effect. RESULTS Z scores determined using the advanced NDB were the same value. Artifacts were often generated in Z score maps derived from the conventional NDB (CONDB). The Z score of the own site NDB (OWNDB) was 70% of that calculated based on the CONDB. The combinatorial difference in compensation (scatter and attenuation) resulted in many artifacts being generated in Z score map images. DISCUSSIONS More artifacts were generated in Z score map images using the novel NDB compared with the CONDB. The novel NDB was comparable to the performance of OWNB. The accuracy of brain function image analysis can be improved the reconstruction conditions and correcting for scatter and attenuation on both the novel NDB and PD.

NMK36 is a novel PET tracer containing a synthetic amino acid analogue anti-[(18)F]FACBC as the active ingredient, and is under development for the use of tumor diagnosis. A Phase I clinical study of NMK36 was conducted to evaluate its safety, biodistribution, and radiation dosimetry in healthy volunteers.Six healthy volunteers (Japanese male) received a bolus injection of NMK36 (174.4-201.4 MBq) intravenously. The safety of NMK36 was evaluated by monitoring signs/symptoms, electrocardiography, recording vital signs, and laboratory examinations at baseline and several time points in 6 days after injection. A total of 11 whole-body PET-CT scans were acquired up to 4 h post-injection, and venous blood and urine samples were also collected for 6 and 24 h post-injection, respectively. Based on the results of the biodistribution study, absorbed radiation dose was estimated by the MIRD method.Although two adverse events occurred after the injection of NMK36, they were mild and disappeared without any specific treatment. NMK36 preferentially accumulated in the pancreas and liver early after injection, followed by rapid clearance from the pancreas. Persistent uptake was observed in the skeletal muscle. NMK36 showed low uptake in the brain, and its urinary excretion was limited (5.40 ± 1.43% of the injected dose at 24 h post-injection). The liver was the critical organ, with a mean absorbed dose of 40.6 μGy/MBq. The estimated effective dose of NMK36 was 13.8 μSv/MBq, which was similar to or lower than those of radiotracers approved for clinical use including [(18)F]FDG.The findings of this study indicate that NMK36 is well tolerated. NMK36 has favorable characteristics for imaging brain and pelvic tumors, such as low brain uptake, slow urinary excretion, and high in vivo stability.

Thus far, cylindrical phantoms with (18)F or (68)Ge/(68)Ga have been used in the standard techniques for determining the cross-calibration factors (CCFs) of PET scanners. This paper describes a new practical method that uses a point-like (22)Na radioactive source for determining CCFs.A point-like (22)Na radioactive source (about 700 kBq) was equipped with a spherical aluminium absorber capsule to ensure the symmetry of the emitted photons. During measurements, the source was moved in the axial direction to cover the whole axial field of view (FOV) of a clinical PET scanner, SET-2400 W. The region-of-interest (ROI) values obtained in reconstructed images without scatter and attenuation corrections were used to calculate the CCFs of the PET scanner.The CCFs obtained by the proposed method agreed with those obtained by the standard cross-calibration (CC) method within a precision of 1.5% (σ). The temporal variations in the CCFs by the standard CC method were reproduced by the proposed method with a precision better than 1%.The CC method with a moving (22)Na point-like radioactive source is practically useful for determining the CCFs of PET scanners and monitoring their variations.

Purpose: We have been developing a practical and reliable calibration scheme based on the use of traceable pointlike sources. In using 22Na sources, special care should be taken to avoid the effects of 1.275-MeV γ rays accompanying β+ decays. The purpose of this study is to validate this calibration method with traceable point-like 22Na sources on various types of PET scanners. Method: The traceable point-like 22Na sources with a spherical absorber design used in this study were of the same type as those used in a previous study. The tested PET scanners included one clinical whole-body PET scanner, four types of clinical PET/CT scanners from different manufacturers, and one small-animal PET scanner. The ROI (region of interest) diameter dependence of ROI values were represented with a fitting function, which was assumed to consist of a recovery part due to spatial resolution and a quadratic background part originating from the scattered γ rays. Results: The calibration factors determined using the point-like source were consistent with those by the standard cross-calibration method within ±4%, which was comparable to the uncertainty of the standard cross-calibration method. Conclusion: The novel calibration scheme based on the use of traceable 22Na point-like sources was validated for six types of commercial PET scanners.

The purpose of this study was to evaluate the clinical effect of a mutanase-containing mouthwash on the accumulation of dental plaque in a doubleblind cross-over investigation.The teeth of twenty dental students were cleaned by scaling and tooth-brushing preceding two test periods of 1 week each. Oral hygiene measures were discontinued during the test periods, while the students rinsed their mouths thrice a day after each meal, one-half using the mutanase-containing mouthwash and the other-half using the placebo mouthwash.At the end of each test period, the plaque accumulation was estimated. Statistical analysis of the data showed that less plaque accumulated during the mutanase than during the placebo period when analysed on all surfaces of all teeth. (P