AIM:To present a case in which low-dose 4-dimensional computed tomographic angiography (4D-CTA) enabled precise classification of a type II endoleak following hybrid arch repair for chronic type B aortic dissection, in the setting of inconclusive findings on conventional CTA. CASE:A 74-year-old woman underwent hybrid arch repair with left common carotid-subclavian bypass and thoracic endovascular aortic repair for chronic type B aortic dissection. Six years postoperatively, aneurysm sac enlargement was noted. Conventional CTA with a 2-phase protocol (early arterial and delayed venous phases) could not distinguish between type Ia and type II endoleaks. Low-dose 4D-CTA (dose-length product: 302.6 mGy·cm) revealed delayed contrast enhancement within the sac during the late arterial phase, consistent with a type II endoleak originating from the left subclavian artery (LSCA). Targeted coil embolization was successfully performed to resolve the endoleak, and contrast inflow from a branch of the LSCA was confirmed by intraprocedural angiography. CONCLUSION:Low-dose 4D-CTA allowed for precise classification of the endoleak and guided appropriate reintervention. This modality represents a useful and practical tool for endoleak evaluation, especially when standard imaging is inconclusive.Clinical ImpactThis case highlights the diagnostic value of 4-dimensional computed tomographic angiography (4D-CTA) in classifying endoleaks after thoracic endovascular aortic repair (TEVAR), particularly when standard CTA is inconclusive. The 4D-CTA identified a type II endoleak from the left subclavian artery, enabling definitive diagnosis and targeted coil embolization. Notably, the scan was performed using a low-dose protocol (dose-length product: 302.6 mGy·cm), substantially lower than the >1000 mGy·cm reported in prior studies while preserving diagnostic quality. Standardized low-dose 4D-CTA protocols may support broader clinical adoption for endoleak evaluation.

In radiology practice, patient body weight is important for contrast media and radiopharmaceutical dosing, radiation dose management, and examination-related workflows, yet it is not consistently available in routine clinical settings. The purpose of this study was to investigate the feasibility of estimating adult body weight using diagnostic CT dose report metrics across CT systems. This retrospective single-center study included 2496 consecutive adults who underwent diagnostic CT on three scanners. Measured body weight served as the reference standard. LightGBM regression was evaluated in three settings: (1) a baseline model using dose report–derived patient size and exposure metrics, including water-equivalent diameter and sex; (2) an extended model additionally incorporating body region and CT system; and (3) scanner-wise cross-validation to assess cross-scanner generalizability. For settings 1 and 2, data were split into training, validation, and test sets (75

18F-FDG PET/CT is crucial for cancer diagnosis; however, respiratory motion often causes misregistration between PET and CT images. This study aimed to evaluate the impact of a custom-made respiratory motion reduction block (RRB) in reducing misregistration and improving image quality in 18F-FDG PET/CT. Methods: The RRB was developed to minimize the effects of respiratory motion. It is a pentagonal block made of Styrofoam designed to compress the upper abdomen. This study included 170 patients who underwent whole-body 18F-FDG PET/CT. Patients were categorized into 4 groups based on the CT and PET scanning technique used: a control free-breathing (FB) group (breath-holding [BH] CT without RRB and respiration-gated [RG] PET), a control RG group (BH CT without RRB with RG PET), a BH RRB group (BH CT with RRB), and a FB RRB group (FB CT with RRB). Various parameters, including the incidence rate and distance of anatomic misregistration, and signal-to-noise ratio, were measured and compared. Results: For the control FB, control RG, BH RRB, and FB RRB groups, the incidence rates of anatomic misregistration between PET and CT images were 47.1%, 27.5%, 34.0%, and 16.7%, respectively. The mean misregistration distances in these groups were 5.1 ± 6.0, 3.1 ± 5.5, 3.8 ± 6.2, and 1.3 ± 3.2 mm, respectively. Furthermore, the RRB improved the signal-to-noise ratio of the liver. Conclusion: The RRB effectively improved registration between PET and CT images. Our approach is cost-effective and provides respiratory motion suppression not only during PET but also during CT scans. The use of RRB with FB PET scanning was found to be more beneficial than respiratory gating.

Patients with congenital heart defects, such as tetralogy of Fallot (TOF) or right ventricular outflow tract stenosis or atresia, often require pulmonary valve replacement (PVR) decades after the primary repair. The purpose of this study was to assess the safety and efficacy of a novel synthetic hybrid fabric (SHF) for PVR in adult congenital heart disease. SHF, consisting of bio-absorbable and non-absorbable yarns coated with cross-linked gelatin, was used in a prospective, multicenter, single-arm pivotal clinical trial involving subjects with an age range of 0–59 years. The overall study was registered in the Japan Registry of Clinical Trials (jRCT1080224691). This paper specifically presents a subgroup analysis focusing on five adult patients (aged 18–42 years) from the multicenter trial. The procedures were performed similarly to those using existing products, with no SHF-specific complications observed. The SHF material allowed surgeons to clearly observe the bioprosthetic valve annulus during suturing. None of the patients required blood transfusion or developed adverse events. At a mean follow-up of 4.5 years (range 4.0–4.9 years), no re-interventions or reoperations were needed. SHF shows promise as a patch material for PVR, offering significant benefits such as clear visualization during surgery, which facilitates precise valve placement. This transparency is crucial for adults with repaired TOF, as it helps reduce surgery time and complication risks. This study suggests that SHF could be a valuable material for adult PVR, extending its potential applications beyond pediatric cardiology.

PURPOSE:The purpose of this study was to evaluate the accuracy of dose information obtained from the digital imaging and communications in medicine (DICOM) using the study description for dose management in nuclear medicine (nuclear medicine SD), and to investigate the feasibility of nuclear medicine SD. METHODS:Single-photon emission nuclear medicine examinations and radionuclide therapy from June 1 to June 30 in 2021 (our hospital master period) and 2023 (nuclear medicine SD period) were included. The dose information in the radioisotope administration record was taken as the true value, and the agreement rate of the examination type, radiopharmaceutical, and dose in the dose management system and the error rate of the dose in the nuclear medicine SD period were calculated. RESULTS:The agreement rate of examination type and radiopharmaceutical was improved from 37.5% to 97.0% by using nuclear medicine SD, and the agreement rate of dose was 54.0%. CONCLUSION:The use of nuclear medicine SD has remarkably improved the integrity of dose information. Dose consistency can be improved by unifying the checking system and the input method of dose information. The feasibility of nuclear medicine SD seems to be high in many facilities, and it may contribute to information collaboration among multi-center facilities and enable centralization of dose management systems.

Objectives:Brain perfusion single-photon emission computed tomography (SPECT) image quality varies depending on SPECT systems. This study aimed to evaluate the relationship between physical parameters and visual analysis for assessment of the brain SPECT image quality. We conducted our phantom study under various conditions in a multi-center and multi-vendor study. Methods:SPECT images of the brain phantom were acquired from eight devices in five institutions. The phantom was filled with 28 kBq/ml of 99mTc solution at the start of scanning. We obtained various data with different acquisition times under clinical reconstruction and acquisition conditions at each institution. Four physical parameters (percent contrast, contrast noise ratio (CNR), asymmetry index (AI), and sharpness index (SI)) were measured with the phantom. Seven observers blindly evaluated all image series and scored them on a scale of 1-3 using four checkpoints: contrast, image noise, symmetry, and sharpness. The average score for all observers was calculated. Results:CNR increased with increasing visual analysis scores for contrast and image noise, both of which were significantly different between the group with scores "<2" and the group with scores "≥2 and <3". AI decreased as the visual analysis score for symmetry increased, and the AI of both groups with scores "≥2 and <3" and "3" were significantly lower than that of the group with scores "<2". Conversely, no relationship with visual analysis was found for percent contrast and SI. Conclusion:We clarified the relationship between physical parameters and visual analysis of a brain phantom in a multi-center and multi-vendor study. CNR and AI showed agreement with visual analysis.

The mechanical circulatory support (MCS) for pediatric patients with severe acute heart failure and poor pulmonary conditions is challenging. Herein, we report the first pediatric case of successfully treated by central Y–Y extra-corporeal membrane oxygenation (ECMO). A 10-year-old boy weighing 35 kg with a body surface area of 1.11 m2 was transferred to our institution in cardiac arrest with ongoing cardiopulmonary resuscitation using intra-aortic balloon pump and peripheral ECMO inserted at the previous hospital. Then, MCS system was converted to central ECMO with left heart drainage due to severe pulmonary congestion and the anticipation of long-term MCS. After 3 days, we converted it to central Y–Y ECMO because of concern about intracavitary thrombus formation due to poor pulmonary conditions. After four more days, the pulmonary conditions were improved, and we converted the MCS system into left ventricular assist device (LVAD) system. He is awaiting the heart transplantation eligibility review in a stable condition. Central Y–Y ECMO system can be used as a bridge to decision also for a pediatric patient with acute severe heart failure and poor pulmonary conditions.

PURPOSE:Japanese normal databases (NDB) for quantitative evaluation of 99mTc myocardial perfusion SPECT have traditionally been created by the filtered back projection (FBP) method but are also applied to the iterative reconstruction (IR) method in some institutions. Although creating the NDB specifically for the IR method is desirable, it has not been done partly due to the ethical aspects of creating an institution-specific database. This study investigated the impact of using NDBs created by the FBP method on quantitative evaluations performed with the IR method. METHODS:We analyzed single-photon emission computed tomography (SPECT) images from patients undergoing myocardial perfusion study in two hospitals with three SPECT vendors. Images were processed with and without various corrections, and a polar map was created by QPS software using a 17-segment model to obtain %uptake and scores. The effects of the reconstruction and correction methods were evaluated to determine the difference in the number of local segmental analyses by coronary artery territories. RESULTS:In most segments, quantitative values showed no significant difference across device types, with or without corrections. However, both choices of the SPECT device and correction methods influenced the scores in specific coronary artery regions. Application of attenuation correction resulted in lower defect scores in the right coronary artery region. CONCLUSION:Applying FBP-derived NDB to the IR method generally yielded a consistent patient diagnosis in terms of defect score analysis. However, since the quantitative evaluation was partly affected by various correction methods and devices, recognizing these characteristics is crucial for enhancing diagnostic accuracy.

Detecting cold as well as hot tumors is vital for interpreting bone tumors on single-photon emission computed tomography (SPECT) images. This study aimed to visually and quantitatively demonstrate the detectability of cold tumors using xSPECT technology compared with that of hot tumors in the phantom study. Five tumors of different sizes and normal bone contained a mixture of 99mTc and K2HPO4 in a spine phantom. We acquired SPECT data using an xSPECT protocol and transverse images were reconstructed using xSPECT Bone (xB) and xSPECT Quant (xQ). Mean standardized uptake values (SUVmean) in volumes of interest (VOI) were calculated. Recovery coefficients (RCs) for each tumor site were calculated with reference to radioactive concentrations. The SUVmeans of the whole vertebral body for hot tumor bone image in cortical bone phantom reconstructed by with xB and xQ were 5.77 and 4.86 respectively. The SUVmean of xB was similar to the true value. The SUVmeans for xB and xQ reconstructed images of cold tumors were both approximately 0.16. The RC of the cold tumor on xQ images increased as the tumor diameter decreased, whereas that of xB remained almost constant regardless of the tumor diameter. In conclusion, the quantitative accuracy of detecting hot and cold tumors was higher in the xB image than in the xQ image. Moreover, the visual detectability of cold tumors was also excellent in xB images.

PURPOSE:This study aimed to evaluate the influence of the scanning speed of whole-body scans on the detectability of positive vertebral bone images in bone scintigraphy. METHODS:We used SIM2 bone phantom to obtain planar images equivalent to scanning speeds of 15, 17, and 20 cm/min. Receiver operating characteristic (ROC) analysis to evaluate lesion detectability and average count (Ct)/pixel, contrast ratio, and contrast-to-noise ratio (CNR) of the normal vertebral body and the simulated tumor site were measured. RESULTS:The average area under the ROC curves (AUC) was 0.936, 0.929, and 0.915 at speeds of 15, 17, and 20 cm/min, respectively. The average AUC at 20 cm/min was significantly lower than that at 15 cm/min (p<0.05) . However, no other significant differences were found (p=0.448, 0.139). The average Ct/pixel and CNR decreased at 15, 17, and 20 cm/min. The contrast ratio did not change. CONCLUSION:The results showed that increasing the scan speed from 15 cm/min to 17 cm/min had no effect on the detection of vertebral lesions. Thus, it is possible to reduce the scan time, albeit slightly.

PURPOSE:The effects of scanning parameters such as CT system performance, CT bed geometry, and upper limb position on effective diameter (ED) and water equivalent diameter (WED) have not been assessed. The purpose of this study was to compare both ED and WED obtained with various CT systems with theoretical values and to assess their accuracy. METHODS:Jaszczak cylindrical phantom (Data Spectrum, Durham, NC, USA), NEMA IEC body phantom (AcroBio, Tokyo), and thoracic bone phantom were used in this study with and without upper limb phantom. The ED, WED, and size-specific dose estimate (SSDE) obtained using 8 types of CT systems were computed using radiation dose control software. RESULTS:The EDs had <5% error for all systems, but the error increased as the aspect ratio of the phantom increased. The accuracy of WED varied depending on the CT systems, with a maximum difference of 3.57 cm between systems. The influence of the upper limb depended on the shape of the bed of the CT systems, which affected the correlation between ED as well as WED and SSDE. CONCLUSION:Although the ED did not show any dependence on the CT system, the accuracy of WED for fusion CT was low. We found that there are issues in the management of scanning data, including the upper limb.

We investigated the impact of the tumor-to-normal bone ratio (TNR) on the concordance rate between a detectability score classified by software (DSsoft) using an automatic quantification package for bone SPECT (Hone Graph) and a detectability score classified by visual assessment (DSvisual), and considered the feasibility of applying this software to various TNR images. 99mTc solution was filled into a SIM2 bone phantom to achieve TNRs of 4, 6, and 8, performed by dynamic SPECT acquisitions performed for 12 minutes; reconstructions were performed using ordered subset expectation maximization at timepoints ranging from 4 to 12 minutes. This yielded a total of 384 lesions (96 SPECT images). We investigated the weighted kappa (κw) coefficient between DSsoft and DSvisual at various TNRs and evaluated the change in analysis accuracy before and after applying newly created analysis parameters. DSs were defined on a 4-point scale (4: excellent, 3: adequate, 2: average, 1: poor), and visual evaluations were conducted by three board-certified nuclear medicine technologists. The κw coefficients between DSsoft and DSvisual were 0.75, 0.97, and 0.93 for TNRs 4, 6, and 8, respectively, with each κw coefficient being significant (p<0.01). In the TNR 4 image group, κw coefficients significantly increased with the implementation of new parameters proposed in this study. We concluded that the software's automatic analysis would be closer to a visual assessment within the TNR range of 4-8 and that applying new parameters derived from this study to images with TNR 4 further improves the software's automatic analysis accuracy of DSsoft. We suggest that software will be a useful tool for optimizing bone SPECT imaging techniques.

BACKGROUNDWe have developed a new hybrid warp-knit fabric for induction of in situ tissue regeneration that has shown appropriate anti-deterioration properties and expandability in preclinical studies. The current study was performed to assess the clinical efficacy and safety of this fabric in the early postoperative period after congenital cardiac surgery.METHODSThe fabric comprises biodegradable (complete degradation period: 2-3 years) and non-biodegradable yarns coated with cross-linked gelatin. A multicenter single-arm 3-year study was conducted. The primary endpoint for regulatory approval was the surgical success rate without death or reintervention related to fabric failure at 1-year after surgery. Secondary endpoints included the incidence of material-related secondary lesions.RESULTSThe fabric was implanted at 41 sites: pulmonary artery (n=18), right ventricular outflow tract (n=12), atrial septum (n=7), and ventricular septum (n=4), in 34 patients of median age 1 year 11 months (range: 4 months-58 years). The surgical success rate was 100%. There were no abnormal findings for the fabric on echocardiography and no serious adverse events in a median follow-up period of 40 months (range: 36-55 months), other than three stenotic lesions that were due to the surgical procedure. These results permitted regulatory approval for use of the fabric in Japan.CONCLUSIONSThe new fabric promoting tissue self-organization through a novel technology showed acceptable efficacy and safety in the early postoperative period after congenital cardiac surgery.

PURPOSE:Motion artifacts caused by heart motion during myocardial perfusion single-photon emission computed tomography (SPECT) can compromise image quality and diagnostic accuracy. This study aimed to evaluate the efficacy of the novel respiratory motion reduction block (RRB) device in reducing motion artifacts by compressing the hypochondrium and improving SPECT image quality. METHODS:In total, 91 patients who underwent myocardial perfusion SPECT with 99mTc-sestamibi were retrospectively analyzed. Patients (n = 28) who underwent SPECT without the RRB were included in the control group, and those (n = 63) who underwent SPECT with the RRB were in the RRB group. The distance of heart motion during dynamic acquisition was measured, and projection data were assessed for patient motion and motion artifacts. Patient motion was classified into various levels, and motion artifacts on SPECT images were visually examined. RESULTS:The distances of heart motion without and with the RRB were 15.4 ± 5.3 and 7.5 ± 2.3, respectively. Compared with the control group, the RRB group had a lower frequency of heart motion based on the projection data, particularly in terms of creep and shift motion. The RRB group had a significantly lower incidence of motion artifacts on SPECT images than the control group. CONCLUSIONS:The RRB substantially reduced specific types of motion, such as shift and creep, and had a low influence on bounce motion. However, it could effectively suppress respiratory-induced heart motion and reduce motion artifacts on myocardial perfusion SPECT, thereby emphasizing its potential for improving image quality.

Three-dimensional (3D) printing is an advanced technology for accurately understanding anatomy and supporting the successful surgical management of complex congenital heart disease (CHD). We aimed to evaluate whether our super-flexible 3D heart models could facilitate preoperative decision-making and surgical simulation for complex CHD. The super-flexible heart models were fabricated by stereolithography 3D printing of the internal and external contours of the heart from cardiac computed tomography (CT) data, followed by vacuum casting with a polyurethane material similar in elasticity to a child’s heart. Nineteen pediatric patients with complex CHD were enrolled (median age, 10 months). The primary endpoint was defined as the percentage of patients rated as “essential” on the surgeons’ postoperative 5-point Likert scale. The accuracy of the models was validated by a non-destructive method using industrial CT. The super-flexible heart models allowed detailed anatomical diagnosis and simulated surgery with incisions and sutures. Thirteen patients (68.4%) were classified as “essential” by the primary surgeons after surgery, with a 95% confidence interval of 43.4–87.4%, meeting the primary endpoint. The product error within 90% of the total external and internal surfaces was 0.54 ± 0.21 mm. The super-flexible 3D heart models are accurate, reliable, and useful tools to assist surgeons in decision-making and allow for preoperative simulation in CHD.

PURPOSE:Investigation of imaging conditions using human body equivalent phantom and neonatal phantom in portable chest radiography of newborns. Although attempts have been made to reduce dose by image processing in portable X-ray radiography of neonates, no evaluation has been made at the raw data level of the images. In this study, we investigated dose reduction from the current imaging conditions using a simulated phantom and a neonatal phantom in terms of raw data level image quality and incident surface dose. METHODS:The pixel values of each region were calculated from chest photographs of newborn infants taken at 60 kV and 2.0 mAs, and the thickness and combination of acrylic, aluminum, and copper were adjusted to create a simulated phantom with equivalent pixel values. The SdNR and incident surface dose at each site obtained from the simulated phantom were compared to obtain imaging conditions equivalent to or better than 60 kV, 2.0 mAs. The neonatal phantom was imaged, and the CNR of the processed images was compared to that of 60 kV, 2.0 mAs. RESULTS:SdNR and incident surface dose results showed that 62 kV, 1.8 mAs was superior. Comparison with neonatal phantoms showed no significant difference. CONCLUSION:The simulated phantom was used to reproduce the clinical situation and to obtain excellent imaging conditions.

Background: Reoperation significantly improves outcomes in tetralogy of Fallot (TOF) patients. However, it is challenging to determine the timing for surgery, especially with complex indications, such as pulmonary regurgitation (PR) with right ventricular outflow tract stenosis or tricuspid regurgitation. Methods: This retrospective study analysed adult TOF patients who underwent reoperation at specialised centres between 2000 and 2015. Exclusions included pulmonary atresia with ventricular septal defect repaired by an extracardiac conduit, double-outlet right ventricle with subaortic ventricular septal defect and pulmonary stenosis and pulmonary atresia. Surgeons determined the primary reoperation indication. Results: Of 154 patients (59.1% male, mean age 35.2 ± 12.0 years), from 10 hospitals, eight deaths (5.2%) occurred over 5.7 years (range 2.5–8.0 years) post-reoperation. The main indications for reoperation were PR, right ventricular outflow tract stenosis, and tricuspid regurgitation (62.3%, 24.0% and 18.2%, respectively). Patients with PR showed more variability in preoperative right ventricular end-diastolic volume index values, particularly without concurrent indications. Conclusion: This study sheds light on reoperation outcomes in Japanese TOF patients before percutaneous treatment availability. Surgical decisions, especially with concurrent indications, need adaptable approaches. Despite the absence of a consensus on preoperative evaluation and thresholds for reoperation, our findings may support current surgical decision-making.

PurposeCurrently, precise patient body weight (BW) at the time of diagnostic imaging cannot always be used for radiation dose management. Various methods have been explored to address this issue, including the application of deep learning to medical imaging and BW estimation using scan parameters. This study develops and evaluates machine learning-based BW prediction models using 11 features related to radiation dose obtained from computed tomography (CT) scans.MethodsA dataset was obtained from 3996 patients who underwent positron emission tomography CT scans, and training and test sets were established. Dose metrics and descriptive data were automatically calculated from the CT images or obtained from Digital Imaging and Communications in Medicine metadata. Seven machine-learning models and three simple regression models were employed to predict BW using features such as effective diameter (ED), water equivalent diameter (WED), and mean milliampere-seconds. The mean absolute error (MAE) and correlation coefficient between the estimated BW and the actual BW obtained from each BW prediction model were calculated.ResultsOur results found that the highest accuracy was obtained using a light gradient-boosting machine model, which had an MAE of 1.99 kg and a strong positive correlation between estimated and actual BW (rho = 0.972). The model demonstrated significant predictive power, with 73% of patients falling within a +/- 5% error range. WED emerged as the most relevant dose metric for BW estimation, followed by ED and sex.ConclusionsThe proposed machine-learning approach is superior to existing methods, with high accuracy and applicability to radiation dose management. The model's reliance on universal dose metrics that are accessible through radiation dose management software enhances its practicality. In conclusion, this study presents a robust approach for BW estimation based on CT imaging that can potentially improve radiation dose management practices in clinical settings.

Objectives To investigate whether the center-of-mass shift distance (CMSD) analysis on whole-body dynamic positron emission tomography (WBD-PET) with continuous bed motion is an objective index for discriminating pathological and physiological uptake in the lower abdominal colon. Methods We retrospectively analyzed the CMSD in 39 patients who underwent delayed imaging to detect incidental focal uptake that was difficult to determine as pathological and physiological on a conventional early-PET (early) image reconstructed by 5-phase WBD-PET images. The CMSD between each phase of WBD-PET images and between conventional early and delayed (two-phase) PET images were classified into pathological and physiological uptake groups based on endoscopic histology or other imaging diagnostics. The diagnostic performance of CMSD analysis on WBD-PET images was evaluated by receiver operator characteristic (ROC) analysis and compared to that of two-phase PET images. Results A total of 66 incidental focal uptake detected early image were classified into 19 and 47 pathological and physiological uptake groups, respectively. The CMSD on WBD-PET and two-phase PET images in the pathological uptake group was significantly lower than that in the physiological uptake group ( p < 0.01), respectively. The sensitivity, specificity, and accuracy in CMSD analysis on WBD-PET images at the optimal cutoff of 5.2 mm estimated by the Youden index were 94.7%, 89.4%, and 89.4%, respectively, which were not significantly different ( p = 0.74) from those of two-phase PET images. Conclusions The CMSD analysis on WBD-PET was useful in discriminating pathological and physiological colorectal uptake in the lower abdominal region, and its diagnostic performance was comparable to that of two-phase PET images. We suggested that CMSD analysis on WBD-PET images would be a novel objective method to omit unnecessary additional delayed imaging.