Japanese Survey of Radiation Dose Associated With Coronary Computed Tomography Angiography　- 2013 Data From a Multicenter Registry in Daily Practice.

BACKGROUND: Although coronary computed tomography angiography (CTA) is frequently used for identifying coronary artery disease, no studies have investigated the radiation dose in detail in Japan. The aim of this study was to estimate the radiation dose of coronary CTA in Japanese clinical practice and to identify the independent predictors associated with radiation dose.Methods and Results:A multicenter, retrospective, observational study (54 institutions) was conducted for estimating the radiation dose of coronary CTA in 2,469 patients between January and December 2013. Independent predictors associated with radiation dose were investigated on linear regression analysis. Median dose-length product (DLP) was 809.0 mGy·cm (IQR, 350.0-1,368.8 mGy·cm), corresponding to an estimated radiation dose of 11 mSv. The DLP per site significantly differed between institutions (median DLP per site, 92-2,131 mGy·cm; P<0.05). Independent predictors associated with radiation dose on multivariable linear regression were body weight, heart rate, non-stable sinus rhythm, scan length, tube voltage setting, electrocardiogram (ECG)-gated scanning protocol, and the image reconstruction technique (P<0.05 each). CONCLUSIONS: The coronary CTA radiation dose was relatively high in 2013, and it varied significantly between institutions. Effective strategies for radiation dose reduction were low tube voltage ≤100 kVp, retrospective ECG-gated scanning with dose modulation technique, prospective ECG-gated scanning, and the iterative reconstruction technique.

Evaluation of a proper cutoff value on quantitative dual-energy perfusion CT for the assessment of acute pulmonary thromboembolism.

Background The cutoff value for assessing the severity of acute pulmonary thromboembolism (PTE) using relative volumetric evaluations of dual-energy perfusion computed tomography (DEpCT) is unclear. Purpose To determine the proper cutoff value for determining the severity of PTE using DEpCT volumetry. Material and Methods A total of 185 patients with venous thromboembolism were included in this study, of whom 61 were diagnosed with acute PTE. DEpCT images were three-dimensionally reconstructed at the following attenuation ranges: 1-2 HU (V2), 1-10 HU (V10), and 1-120 HU (V120). The ratios of low perfusion areas associated with each threshold range per V120 were also calculated, and the relative ratios were expressed as %V2 to %V10. These values were compared with factors indicating the severity of PTE, including the pulmonary arterial pressure, heart rate, CT angiographic obstruction index (CTOI), and right/left ventricular diameter ratio (RV/LV). Results The area under the curve (AUC) of %V2 was highest (0.783) among these values (95% confidence interval, 0.710-0.856) based on the presence of IPCs. The %V2 showed moderate correlations with CTOI (r = 0.36, P = 0.005) and RV/LV (r = 0.36, P = 0.004) in the patients with acute PTE. Conclusion Volumetric evaluations of DEpCT images using the lowest attenuation threshold range (1-2 HU) exhibit the best correlation with factors suggesting the severity of acute PTE.

The Optimal Body Size Index with Which to Determine Iodine Dose for Hepatic Dynamic CT: A Prospective Multicenter Study.

PURPOSE: To identify the body size parameter that exhibits the best correlation with aortic and hepatic enhancement at hepatic dynamic computed tomography (CT) in a large patient population enrolled in a multicenter study. MATERIALS AND METHODS: This prospective study was approved by the ethics committee of each of the 31 participating institutions where 1342 patients were enrolled between April 2012 and September 2013. All patients provided either written or oral informed consent. All patients underwent hepatic dynamic CT, which included preenhanced, hepatic arterial phase (HAP), and portal venous phase (PVP) scanning, performed with the routine scanning protocol of each institution. Changes in CT number (in Hounsfield units) per gram of iodine in the aorta (eA/I) and liver (eL/I) during HAP and PVP scanning were recorded for each patient. Hierarchical multivariate linear regression analysis was performed in which the outcome variable was either eA/I or eL/I; the independent variables were age, sex, one body size parameter (height, body weight, body mass index, lean body weight [LBW], or body surface area), and liver function (aspartate aminotransferase, albumin, and total bilirubin levels). A two-level hierarchical model in which patients were level 1 and the institution was level 2 was used. RESULTS: Hierarchical multivariate linear regression analysis revealed that in the population not stratified by sex, body size was significantly correlated with eA/I and eL/I (P < .001) and that LBW exhibited the strongest correlation with eA/I and eL/I (r = -0.561 and r = -0.601, respectively). Sex-stratified analysis showed that LBW was more strongly correlated with eA/I and eL/I in women (r = -0.779 and r = -0.948, respectively) than in men (r = -0.500 and r = -0.494, respectively) or in the nonstratified total population. CONCLUSION: Among body size parameters, LBW exhibited the strongest correlation with aortic and hepatic enhancement, especially in women.

The usefulness of a diagnostic method combining high-resolution CT findings and serum markers for cytomegalovirus pneumonia and pneumocystis pneumonia in non-AIDS patients.

BACKGROUND: The combination of high-resolution computed tomography (HRCT) findings and serum markers would be of great value in diagnosing cytomegalovirus pneumonia (CMVP) and pneumocystis pneumonia (PCP) considering low invasiveness. PURPOSE: To compare the HRCT findings of CMVP and PCP and to evaluate the differences in HRCT findings between patients diagnosed based on pathologic evidence and serum markers. MATERIAL AND METHODS: Two radiologists retrospectively evaluated the HRCT findings of 21 patients with CMVP and 70 patients with PCP. Eight patients with CMVP and 32 patients with PCP were diagnosed based on pathologic evidence ("Path" group), while 13 patients with CMVP and 38 patients with PCP were diagnosed based on serum markers (CMV antigenemia, ß-D-glucan) ("Serum-Marker" group). A total of 19 CT morphological criteria were evaluated, and the significance of the differences between the two diseases and between the "Path" and "Serum-Marker" groups with respect to each disease was calculated. RESULTS: The presence of small nodules, the tree-in-bud pattern, and the halo sign was found more frequently in the CMVP group. Extensive ground-glass attenuation (GGA), a mosaic pattern, and a diffuse distribution were observed more frequently in the PCP group. There were significant differences between the "Path" and "Serum-Marker" groups in average extent of consolidation and distribution of consolidation in PCP, and the distribution of GGA in CMVP, respectively. CONCLUSION: The combined use of HRCT findings and serum markers is useful for the diagnosis of CMVP and PCP in non-AIDS patients. The typical HRCT findings for the differential diagnosis included extensive GGA with mosaic pattern in PCP and nodules, nodules with or without the tree-in-bud pattern, and the halo sign in CMVP.

Effectiveness of using low-dose computed tomography to assess patency in gastrointestinal tracts with a patency capsule.

BACKGROUND/AIMS: A patency capsule (PC) is used to safely perform capsule endoscopy. When the PC is not excreted within the defined time frame, radiography often cannot localize the PC. Computed tomography (CT) localizes a PC more definitively than radiography. We evaluated the localization of PCs using low-dose (LD)-CT. METHODOLOGY: Forty-nine patients received a PC and 33 did not excrete the PC within the defined time frame and underwent radiography and LDCT with a 90% exposure reduction. RESULTS: LDCT localized the PC in 31 patients (93.9%), whereas radiography localized it in 7 (21.2%), indicating a significantly higher detection rate with LDCT (P<0.0001). PC retention in the small intestine was confirmed by LDCT in 4 patients. Retention was not observed during capsule endoscopy in the patients with confirmed patency of the gastrointestinal tract. In 21 patients who underwent LDCT with the conventional photographing area, the effective radiographic exposure dose associated with LDCT was 1.43±1.08 mSv. Conversely, in the 12 patients who underwent LDCT with a reduced photographing area, the effective dose was reduced to 0.62±0.27 mSv (P<0.05). CONCLUSION: LDCT with a reduced exposure dose can definitively localize a PC. Therefore, this method may allow capsule endoscopy to be performed for more diseases.

The effect of the section thickness used for 2- and 3-dimensional quantification of dual-energy perfusion computed tomography.

PURPOSE: To retrospectively investigate the effect of the section thickness used for quantifying dual-energy perfusion computed tomography (DEpCT) during 2- and 3-dimensional evaluation. METHODS: Sixty-six patients (22 males and 44 females; mean age, 59.3 years) suspected of having an acute pulmonary embolism underwent DEpCT, and 15patients were diagnosed to have intrapulmonary clots (IPCs). Two-dimensional DEpCT images were reconstructed into various section thicknesses from 1 to 10 mm at the main pulmonary artery, and the ratios of the low attenuation area (LAA) ranging from 1 to 5 HU (%LAA5) and 10 HU (%LAA10) on DEpCT were compared with the relative areas of the lung with attenuation coefficients lower than -950 HU (RA-950) using the lung CT images of each section thickness. Three-dimensional values of DEpCT were reconstructed with 3 different section thicknesses (1, 3, and 10 mm) and were analyzed for the presence of IPC burden using the factors suggesting IPC burden, including the right/left ventricular diameter ratio and CT obstruction index. RESULTS: The mean attenuation and image noise were decreased as the section thickness increased. In the 2-dimensional analysis, the %LAA5 and %LAA10 had the smallest value at 1-mm section, and DEpCT with thinner sections had a correlation with the RA-950 (r = 0.22-0.23, P < 0.05). The 3-dimensional values of DEpCT reconstructed with a 1- or 3-mm section thickness had a correlation with the CT obstruction index (r = 0.52-0.59, P < 0.05) and right/left ventricular diameter ratio (r = 0.60-0.68, P < 0.01). CONCLUSIONS: The thinner images should be used for 2- and 3-dimensional quantification of DEpCT.

Dual-source computed tomography coronary angiography in patients with high heart rate.

Although single-source 64-multislice computed tomography coronary angiography (SSCTA) needs to reduce heart rate (HR), dual-source computed tomography coronary angiography (DSCTA) can acquire images even in tachycardia. The accuracy of DSCTA during tachycardia is compared to the accuracy of SSCTA at reduced HR. Patients who received invasive coronary angiography and either SSCTA or DSCTA were included. In the SSCTA group, HR was reduced to <65 beats per minute (bpm) with ß-blocker (n = 27), while in the DSCTA group patients whose HR was >65 bpm were selected (n = 27). The diagnostic accuracy for significant coronary stenosis was calculated by comparing the invasive coronary angiography. Using dual-Doppler echocardiography, isovolumic relaxation time (IRT) and diastasis time (DT) were evaluated in these patients. In SSCTA, sensitivity was 89 %, specificity 99 %, the positive predictive value (PPV) 94 %, and the negative predictive value (NPV) was 98 %. In DSCTA, sensitivity was 96 %, the specificity was 99 %, PPV was 91 %, and NPV was 99 % (all NS compared to SSCTA). When HR was >75 bpm, DT was markedly shortened (<83 ms), however IRT was maintained >85 ms. Thus, the image reconstruction at the phase of IRT is feasible in DSCTA because of its temporal resolution of 83 ms. High temporal resolution of DSCTA shows equivalent accuracy of coronary stenosis detection to SSCTA, without reducing heart rate, because of its image reconstruction at IRT.

Radiotherapy for intraarticular venous malformations of the knee.

Intraarticular venous malformation (IAVM) of the knee is a rare vascular disease that manifests with pain, swelling, and hemarthrosis. A young man with left knee pain and swelling was admitted to our institution for the treatment of the IAVM of the left knee which was diagnosed by a local orthopedic doctor via arthroscopy. A total dose of 40 Gy of radiotherapy was delivered with a daily dose of 2.0 Gy using 6 MV X-ray beams and a linear accelerator through anteroposterior portals. Fifteen months after radiotherapy, follow-up examination using radiologic imaging showed distinct shrinkage of the venous malformations. Swelling and pain of the left knee had decreased, and range of motion of the left knee was maintained. This report describes a case involving a 38-year-old man with IAVM of the left knee in whom favorable outcomes were obtained in response to radiotherapy.

[Imaging of thrombus].

The purpose of this article is to review the imaging of arterial and venous thrombus. Imaging plays a crucial role in the diagnosis or exclusion of mural thrombus in patients with arteriosclerosis because of the increased risk of distal embolism in the procedures and of venous thrombosis in patients with coagulation disorder. Enhanced spatial resolution, temporal resolution, and tissue characterization of imaging techniques show precise features of mural thrombus or have improved identification of unsuspected venous thrombosis. It is important to recognize the spectrum of various imaging features of thrombus. This article reviews the imaging appearances of arterial and venous thrombus using ultrasound, computed tomography, magnetic resonance imaging, and radionuclide.

Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT.

BACKGROUND: Dual-energy perfusion CT (DEpCT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. PURPOSE: To evaluate if volumetric evaluation of DEpCT can be used as a predictor of right heart strain by the presence of IPCs. MATERIAL AND METHODS: One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DEpCT using a 64-slice dual-source CT. DEpCT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V120), 1-15 HU (V15), 1-10 HU (V10), and 1-5 HU (V5). Each relative ratio per V120 was expressed as the %V15, %V10, and %V5. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. RESULTS: PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V15, V10, V5, %V15, %V10, and %V5 were also significantly higher than those without IPC (P ≤ 0.001). %V5 had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements. CONCLUSION: The volumetric evaluation by DEpCT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.

Image-guided percutaneous gastrostomy using modified large balloon as access target.

BACKGROUND/AIMS: To develop a novel percutaneous radiologic gastrostomy using a large-bore, rupture-free, balloon (RFB) catheter in patients with a swallowing disturbance due to a neurological disorder. METHODOLOGY: Consecutive patients underwent percutaneous gastrostomy placement using a balloon catheter with a 5.0-cm 5.0-cm, large-bore, rupture-free balloon on the tip between August 2010 and December 2011. The large balloon in the stomach was percutaneously punctured by the needle, the guide wire was inserted through the abdominal wall, and the push-type gastrostomy tube was finally inserted over the guide wire via the oral cavity. Technical success and complications were evaluated. RESULTS: Fifteen patients (10 men, 5 women; age range, 47-82 years; mean age, 71.7 years) who had cerebral infarction (n=8), intracerebral hemorrhage (n=4), and subarachnoid hemorrhage (n=3) underwent percutaneous radiologic gastrostomy. The procedures were technically successful in all patients. The mean procedure time was 34+- 9 (SD) min (range, 20-47 min). The average follow-up was 158 days (range, 14 - 655 days). No major complications related to the procedure were encountered. CONCLUSION: Image-guided gastrostomy using a large-bore RFB catheter is an effective method of gastric feeding in patients with swallowing disturbance due to a neurological disorder.

Radiological image-guided placement of covered Niti-S stent for palliation of dysphagia in patients with cervical esophageal cancer.

The aim of this study was to evaluate the clinical effectiveness of covered Niti-S stent placement under multidetector CT and fluoroscopy guidance for the palliation of dysphagia in patients with cervical esophageal cancer. Under radiological imaging guidance using axial and sagittal CT scans, and fluoroscopy, Niti-S esophageal stents were placed in ten consecutive patients with complete obstruction caused by cervical esophageal cancer (9 men and 1 woman; age range = 54-79 years; mean age = 68.1 years) between February 2010 and December 2011. The procedure time and technical success rate were evaluated. Swallowing improvement was assessed by the following items: ability to eat and/or swallow (graded as follows: 3 = ability to eat normal diet, 2 = ability to eat semisolids, 1 = ability to swallow liquids, 0 = complete obstruction). Procedural and post-procedural complications were also evaluated. Survival (mean ± SD) was examined. The mean (±SD) procedure time was 40 ± 19 min (range = 21-69 min). Stent placement was technically successful in all patients; inadequate stent deployment did not occur in any case. Ability to eat and/or swallow was improved and scored 2.4 (score 3 in 5 cases, score 2 in 4 cases, score 1 in 1 case, and score 0 in no case) after stent placement. No major or post-procedural complications were encountered. The mean survival time was 131 ± 77 days (range = 31-259 days). Niti-S stents appeared to be a safe and effective device for the palliation of dysphagia caused by advanced cervical esophageal cancer. Multidetector CT and fluoroscopy image guidance helped the operators accurately place the stents in the cervical esophagus.

Cisterna chyli in patients with portal hypertension: evaluation with MR imaging.

PURPOSE: To evaluate the difference in the caliber of cisterna chyli between patients with and without portal hypertension on magnetic resonance imaging (MRI) and to assess the alteration of the caliber of cisterna chyli related to contraction waves during serial T2-weighted MRI. MATERIALS AND METHODS: This study included 177 patients with and without portal hypertension who underwent two sets of T2-weighted MRI. MR images were evaluated for the visibility of cisterna chyli, the difference in the diameter of cisterna chyli between two patients groups, and the alteration in the diameter of cisterna chyli during serial T2-weighted MRI. RESULTS: The mean maximal diameter of cisterna chyli in patients with portal hypertension (4.97 ± 1.87 mm, range; 2.5-13.1 mm) was significantly larger (P < 0.001) than that in patients without portal hypertension (3.37 ± 1.25 mm, range; 1.5-6.8 mm). In 132 patients with visible cisterna chyli and portal hypertension, 25 (19%) patients had a positive caliber change of cisterna chyli of more than 2 mm between two sets of T2-weighted MR images. CONCLUSION: The dilatation of cisterna chyli can be demonstrated at MRI in patients with portal hypertension. Additionally, the positive caliber change of cisterna chyli related to contraction waves was observed in subsets of patients during serial T2-weighted MRI.

Relationship between the trochlear groove angle and patellar cartilage morphology defined by 3D spoiled gradient-echo imaging.

OBJECTIVE: To examine whether the femoral trochlear groove angle (TGA) is a determinant of the patellar cartilage volume and patellar cartilage damage. MATERIALS AND METHODS: Patellar cartilage was evaluated by MR imaging in 66 patients (22 males and 44 females) with knee pain. Fat-suppressed 3D spoiled gradient-echo images were used to calculate the cartilage volume and to grade the cartilage damage. The proximal and distal TGAs were measured from axial PD-weighted FSE MR images with fat suppression. RESULTS: For every increase in the TGA at the distal femur, the patellar cartilage volume was significantly increased by 6.07 × 10(-3) cm(3) (95% CI: 1.27 × 10(-3), 10.9 × 10(-3)) after adjustment for age, gender, and patellar bone volume (P < 0.05). The MR grade of medial patellar cartilage damage progressed as the distal TGA became narrower, although there was no significant correlation between the distal TGA and the MR grading of patellar cartilage damage. CONCLUSION: A more flattened distal TGA was associated with increased patellar cartilage volume. However, there was no association between TGA and patellar cartilage defects.

Relationship between cartilage volume using MRI and Kellgren-Lawrence radiographic score in knee osteoarthritis with and without meniscal tears.

OBJECTIVE: The purpose of our study was to evaluate the correlation between the Kellgren-Lawrence (KL) radiographic score and the femoral and tibial cartilage volumes determined by MRI in patients with knee osteoarthritis. The effect of meniscal tears and extrusion on the cartilage volume was also examined. SUBJECTS AND METHODS: Knee cartilage was evaluated by MRI in 74 patients (20 men and 54 women) who were categorized according to the KL score. Sagittal fat-suppressed 3D spoiled gradient-echo images were obtained to calculate the cartilage volume. The cartilage volume was determined for the lateral femoral cartilage, medial femoral cartilage, lateral tibial cartilage, and medial tibial cartilage. The femoral condylar bone volume was measured to adjust for bone size in each cartilage volume measurement. RESULTS: After adjusting for age, sex, and femoral condylar bone volume, the cartilage volumes were significantly different between the grades in all compartments. Additionally, significant correlations were observed between the KL score and the adjusted cartilage volumes of lateral femoral cartilage and lateral tibial cartilage without a meniscal tear and between the KL score and the adjusted cartilage volume of medial femoral cartilage with and without a meniscal tear. CONCLUSION: These findings showed a significant negative association between cartilage volume and the KL score. The cartilage volume of medial femoral cartilage may be more affected by the severity of osteoarthritis grade than the presence of a meniscal tear. In contrast, the cartilage volume in the lateral tibiofemoral compartment may be easily affected by the presence of a meniscal tear.

Evaluation of small ischemic lesions after carotid artery stenting: the usefulness of thin-slice diffusion-weighted MR imaging.

INTRODUCTION: There has been concern regarding the usefulness of diffusion-weighted imaging (DWI) to evaluate the ischemic lesions associated with carotid artery stent placement (CAS). Some small lesions may be detected not by standard DWI but by thin-slice DWI alone, since most of the cerebral lesions are very small in size and clinically silent. The purpose of this study is to compare the detectability of the small ischemic lesions after CAS by standard and thin-slice DWI. METHODS: Both standard DWI with slice thickness of 6 mm and thin-slice DWI with slice thickness of 2 mm were obtained at the same MR examination within 2 to 7 days after 20 procedures of CAS in 17 patients. Number and measured diameter size of the detected lesions on both DWI were compared. RESULTS: All CAS procedures in 17 patients were successfully completed. The focal ischemic lesions were detected in 14 of 20 on thin-slice DWI and seven examinations on standard DWI. The total numbers of hyperintense lesions were 31 on thin-slice DWI and ten on standard DWI (p < 0.001). The sizes of these ten lesions on thin-slice DWI were larger than those of standard DWI, and the mean size of the thin-slice DWI and that of standard DWI were significantly different (p < 0.005). CONCLUSION: Thin-slice DWI was able to detect small cortical lesions better than standard DWI. Thin-slice DWI may be useful to evaluate small silent ischemic lesions after CAS.

MRI of soft-tissue tumors: fast STIR sequence as substitute for T1-weighted fat-suppressed contrast-enhanced spin-echo sequence.

OBJECTIVE: The purpose of this study was to assess the value of the fast STIR sequence in comparison with the T1-weighted fat-suppressed contrast-enhanced sequence in the evaluation of soft-tissue tumors. MATERIALS AND METHODS: Sixty-seven soft-tissue tumors imaged with both STIR and T1-weighted fat-suppressed contrast-enhanced sequences were evaluated. The signal-to-noise and contrast-to-noise ratios of the tumors in comparison with normal muscle, bone marrow, and fat were measured. Subjective image contrast between soft-tissue tumors and the nearest normal tissue was evaluated by two observers. The observers classified the soft-tissue tumors as benign or malignant using a 5-point scale, and sensitivity, specificity, and accuracy were calculated. The results of the two readings were assessed with receiver operating characteristic analysis. RESULTS: The contrast-to-noise ratios of all tumors in comparison with muscle (p < 0.01), bone marrow (p < 0.05), and fat (p < 0.05) were significantly higher on the fast STIR images than on the T1-weighted fat-suppressed contrast-enhanced images. Both observers' mean ratings of benign, malignant, and all tumors in comparison with muscle on fast STIR images were significantly higher than those on T1-weighted fat-suppressed contrast-enhanced images. For both observers, the mean sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve in evaluation of the fast STIR images did not differ significantly from those in evaluation of the T1-weighted fat-suppressed contrast-enhanced images. CONCLUSION: The fast STIR sequence is excellent for evaluation of soft-tissue tumors, and contrast-enhancement is not always needed.

Differentiation of FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer with dual-time point F-18-fluorodeoxy-glucose PET/CT scan.

OBJECTIVE: To evaluate the ability of dual-time point F-18-fluorodeoxy-glucose (FDG) PET/CT scans to differentiate FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer. METHODS: A total of 64 FDG-avid recurrent lesions (local tumor recurrence or lymph node metastases) in 52 patients and 38 FDG-avid compromised benign lesions after surgery in 37 patients were included in the study. FDG PET/CT study was performed at 60 and 120 min after intravenous injection of 3.5 MBq/kg FDG. The maximum SUV (SUVmax) on the early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis. RESULTS: The average early SUVmax, delayed SUVmax and DeltaSUVmax% were 4.9 +/- 2.6, 6.0 +/- 3.6 and 18.2% +/- 18.8 in FDG-avid recurrent lesions, and 2.1 +/- 0.8, 1.8 +/- 1.0 and -17.8% +/- 21.3 in FDG-avid benign lesions, respectively. Delayed SUVmax was significantly increased compared with early SUVmax in recurrent lesions (P < 0.0001), while it was decreased in benign lesions (P < 0.0001). All the three parameters in recurrent lesions were significantly higher than those in benign lesions (P < 0.0001). The highest diagnostic accuracy of the differentiation was achieved by the combined use of the optimal parameter of delayed SUVmax > 2.5 and %DeltaSUVmax > 0%, with a sensitivity of 90.6%, specificity of 81.5%, accuracy of 87.2%, NPV of 89.2%, and PPV of 83.7%, which were better than the respective values obtained with the use of delayed SUVmax > 2.5 alone or %DeltaSUVmax > 0% alone (P < 0.005 and P < 0.05, respectively), and the use of the traditional parameter of early SUVmax > 2.5 (P < 0.005). CONCLUSIONS: This approach with SUVmax estimation appears to improve the differentiation between FDG-avid loco-regional recurrent of breast cancer and compromised benign lesions after surgery, since delayed scanning significantly enhances the difference in FDG uptake between these lesions.

Findings of hepatopulmonary syndrome on breath-hold perfusion SPECT-CT fusion images.

Pulmonary perfusion SPECT-CT fusion images were used to characterize CT manifestations of intrapulmonary arteriovenous communications (AVC) causing right-to-left shunt and hepatopulmonary syndrome (HPS). After scanning the whole body and obtaining multiple view images of the lung, deep-inspiratory breath-hold (DIBrH) SPECT was obtained in 2 patients with HPS, which was automatically and three-dimensionally co-registered with DIBrH CT. In both patients, the whole body scan depicted systemic organs and confirmed the existence of right-to-left shunt. DIBrH SPECT-CT fusion images showed that perfusion defects were predominantly located at subpleural reticulo-nodular opacities and/or dilated vessels in the lung base. Subpleural reticulo-nodular opacities and/or dilated vessels in the lung base appear to be characteristic CT manifestation of intrapulmonary AVC in HPS.

[Development of comprehensive image processing technique for differential diagnosis of liver disease by using multi-modality images-pixel-based cross-correlation method using a profile-].

Imaging techniques such as high magnetic field imaging and multidetector-row CT have been markedly improved recently. The final image-reading systems easily produce more than a thousand diagnostic images per patient. Therefore, we developed a comprehensive cross-correlation processing technique using multi-modality images, in order to decrease the considerable time and effort involved in the interpretation of a radiogram (multi-formatted display and/or stack display method, etc). In this scheme, the criteria of an attending radiologist for the differential diagnosis of liver cyst, hemangioma of liver, hepatocellular carcinoma, and metastatic liver cancer on magnetic resonance images with various sequences and CT images with and without contrast enhancement employ a cross-correlation coefficient. Using a one-dimensional cross-correlation method, comprehensive image processing could be also adapted for various artifacts (some depending on modality imaging, and some on patients), which may be encountered at the clinical scene. This comprehensive image-processing technique could assist radiologists in the differential diagnosis of liver diseases.