VI-RADS for Bladder Cancer: Current Applications and Future Developments.

Bladder cancer (BCa) is among the ten most frequent cancers globally. It is the tumor with the highest lifetime treatment-associated costs, and among the tumors with the heaviest impacts on postoperative quality of life. The purpose of this article is to review the current applications and future perspectives of the Vesical Imaging Reporting and Data System (VI-RADS). VI-RADS is a newly developed scoring system aimed at standardization of MRI acquisition, interpretation, and reporting for BCa. An insight will be given on the BCa natural history, current MRI applications for local BCa staging with assessment of muscle invasiveness, and clinical implications of the score for disease management. Future applications include risk stratification of nonmuscle invasive BCa, surveillance, and prediction and monitoring of therapy response. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

VI-RADS score system - A primer for urologists.

Bladder cancer (BCa) is one of the most common cancers worldwide and is also considered to be one of the most relapsing and aggressive neoplasms. About 30% of patients will present with muscle invasive disease, which is associated with a higher risk for metastatic disease. The aim of this article is to review the state of art imaging in Radiology, while providing a complete guide to urologists, with case examples, for the rationale of the development of the Vesical Imaging Reporting and Data System (VI-RADS), a scoring system emphasizing a standardized approach to multiparametric Magnetic Resonance Imaging (mpMRI) acquisition, interpretation, and reporting for BCa. Also, we examine relevant external validation studies and the consolidated literature of mpMRI for bladder cancer. In addition, this article discusses some of the potential clinical implications of this scoring system for disease management and follow-up.

Clinical Practice Guidelines for Bladder Cancer 2019 edition by the Japanese Urological Association: Revision working position paper.

The Clinical Practice Guidelines for Bladder Cancer edited by the Japanese Urological Association were first published in 2009 and a revised edition was released in 2015. Four years has passed since the 2015 edition, and the clinical practice environment surrounding bladder cancer has drastically changed during that time. The main changes include: (i) insurance coverage of a new diagnostic method for non-muscle-invasive bladder cancer; (ii) insurance coverage of an immune checkpoint inhibitor in advanced and metastatic bladder cancer; and (iii) advances in robot-assisted radical cystectomy as a minimally invasive treatment for muscle-invasive bladder cancer. A paradigm shift in bladder cancer diagnosis and treatment is occurring day by day. Therefore, in this 2019 edition, while dealing with the above changes, we carefully selected clinical questions with clear evidence and included other clinically important points in the general statement. We also added a new chapter on rare cancers of the urinary tract. As a new method for the evaluation of study evidence level, we introduce "The Grading of Recommendations Assessment, Development and Evaluation" system modified to Japanese by the Medical Information Network Distribution Service.

Clinical Practice Guidelines for Bladder Cancer 2019 update by the Japanese Urological Association: Summary of the revision.

OBJECTIVES: Despite just a 4-year interval from the last version (2015) of the Clinical Practice Guidelines for Bladder Cancer, several dramatic paradigm shifts have occurred in the latest clinical practice regarding both the diagnosis and treatment of bladder cancer. Herein, we updated the 2019 version of the Clinical Practice Guidelines for Bladder Cancer under the instruction of the Japanese Urological Association. METHODS: We previously reported in a revision working position paper for Clinical Practice Guidelines for Bladder Cancer 2019 edition and described the methods of revision detail. RESULTS: The major points of change in the 2019 version are presented and explanations are given as follows: (i) introduction of the new reference assessment system; (ii) modification of the risk classification for non-muscle-invasive bladder cancer; (iii) addition of clinical questions for the new tumor-visible techniques in non-muscle-invasive bladder cancer; (iv) inclusion of minimally invasive surgeries for muscle-invasive bladder cancer and immune checkpoint inhibitors for locally advanced/metastatic muscle-invasive bladder cancer; (v) overview chapter of the histological variant of urothelial cancer and rare cancers of the bladder; and (vi) recommendation of follow up in non-muscle-invasive bladder cancer and muscle-invasive bladder cancer. CONCLUSIONS: Guidelines should be updated based on the current evidence and updates carried out without delay. The hope is that this guidelines will be assessed by many urologists and will be the cornerstone for the next revision.

Analysis of MRI Values and Hemoglobin and Total Protein Concentrations of Cystic Ovarian Tumors.

BACKGROUND: Endometrioma generally shows higher intracystic signal intensity (SI) than mucinous cystadenoma (MCA) on T1 -weighted imaging (T1 WI). Nonendometrioma-associated malignant ovarian epithelial tumors (nonendometrioma group) often show higher intracystic SI than benign tumors on T1 WI, while the converse is true for endometrioma and endometrioma-associated malignant tumors (endometrioma group). However, it is sometimes difficult to differentiate between hemorrhagic and mucinous content based on SI on T1 WI. Hemoglobin (Hb) and protein are both speculated to shorten T1 . PURPOSE: To examine MRI values and Hb and total protein (TP) concentrations in ovarian tumors. STUDY TYPE: Prospective. SPECIMEN: In all, 182 samples from 167 cystic ovarian tumors. FIELD STRENGTH: 1.5T, spin-echo T1 WI, fast spin-echo T2 WI. ASSESSMENT: The in vivo intracystic/psoas major muscle SI ratios were determined as references for intracystic SI. T1 and T2 values, cystic content inversion times (TIs), and Hb and TP concentrations were determined to evaluate differences between 1) endometrioma and MCA; 2) benign, borderline, and malignant tumors in the nonendometrioma group; and 3) those in the endometrioma group. STATISTICAL TESTS: Wilcoxon's rank-sum test, Kruskal-Wallis test. RESULTS: In endometriomas (n = 43) and MCAs (n = 27), mean T1 and T2 (TP, Hb concentrations) were 428 and 162 msec (52.7, 12.00 g/dl) and 1639 and 600 msec (7.1, 0.06 g/dl), respectively (all, P < 0.0001). In the nonendometrioma group (epithelial benign, n = 56; borderline, n = 20; malignant, n = 25), these values were 1657 and 696 msec (6.4, 0.35 g/dl), 1235 and 400 msec (13.5, 0.83 g/dl), and 1184 and 311 msec (19.7, 0.84 g/dl), respectively (all, P < 0.0001). In the endometrioma group (endometrioma, n = 43; borderline, n = 3; malignant, n = 8), these values were 428 and 162 msec (52.7, 12.00 g/dl), 427 and 108 msec (16.6, 3.07 g/dl), and 1010 and 268 msec (24.2, 1.56 g/dl), respectively (all, P < 0.05). DATA CONCLUSION: TP and Hb concentrations were higher in the contents of endometriomas than MCAs, leading to lower T1 and T2 values. In the nonendometrioma group, TP and Hb concentrations were higher in the cystic contents of borderline and malignant tumors than benign tumors, leading to lower T1 and T2 values. Conversely, the cystic contents of borderline and malignant tumors in the endometrioma group showed lower TP and Hb concentrations compared to endometriomas, leading to higher T1 and T2 values. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1133-1140.

A case report of ectopic pancreatitis in an isolated enteric duplication cyst.

BACKGROUND: Isolated enteric duplication cyst is an intestinal duplication cyst found in a distant location from the intestinal tract and it is said to have its own blood supply. Meckel's diverticulm is considered as an antimesenteric structure and has its own blood supply. However, there are some reported cases of Meckele's diverticum in the mesenteric side. Ectopic pancreas may be found in both entities. CASE PRESENTATION: A 5-year-old girl presented with increasing abdominal pain around the umbilicus. On laboratory investigation serum pancreatic enzymes and C-reactive protein were elevated. Abdominal computed tomography (CT) revealed a normal pancreas but a cystic lesion in the mesentery of the ileum. A nodule with a marked enhancement was observed in the wall of the lesion. During the laparoscopy, the lesion was found at the root of the mesentery and was distant from the ileum. The lesion was resected suspecting an abscess. Pathologically, the wall of the lesion consisted of small bowel like tissue, and pancreatic tissue was seen beneath the mucosa. There were some post inflammatory changes in the pancreatic tissue. Retrospectively on thin slice enhanced CT, an independent blood supply was noted. Based on these findings, a diagnosis of ectopic pancreatitis in an iliac intestinal duplication cyst was made. CONCLUSION: Isolated enteric duplication cyst in the root of ileal mesentery and mesenteric Meckel's diverticulum have similarities. In the present case, the diagnosis of isolated enteric duplication cyst was made since it was found distant from the ileum. It is important to consider the possibility of ectopic pancreatitis when serum pancreatic enzymes are elevated even when the pancreas appears normal.

Can bladder preservation therapy come to the center stage?

Decision-making in urological cancer care requires a multidisciplinary approach for refinement, but its impact on urothelial carcinoma of the bladder has not been fully addressed for the past three decades, except for the latest immunological checkpoint inhibitor approved by the U.S. Food and Drug Administration for metastatic muscle-invasive bladder cancer that is resistant to platinum-based chemotherapy. For the time being, radical cystectomy is the gold standard of curative therapy for muscle-invasive bladder cancer. Trimodal therapy that combines chemotherapy for the purpose of radiation sensitization, external beam radiotherapy and transurethral resection of bladder tumor has emerged as a potential alternative treatment option that preserves the bladder. In lack of randomized studies for bladder preservation therapy compared with surgery, the principles of management of urothelial carcinoma of the bladder have evolved in recent times, with an emphasis on bladder preservation. A number of bladder preservation techniques are available to the surgeon; however, appropriately selected patients with muscle-invasive bladder cancer should be offered the opportunity to discuss various treatment options, including organ-sparing trimodal therapy. The aim of the present study was to compare the primary outcomes of the available treatment methods and identify the sources of variance among studies. A review of various bladder preservation techniques in vogue for the management of urothelial carcinoma of the bladder is discussed.

Diagnostic performance of reduced-dose CT with a hybrid iterative reconstruction algorithm for the detection of hypervascular liver lesions: a phantom study.

OBJECTIVES: To investigate the diagnostic performance of reduced-dose CT with a hybrid iterative reconstruction (IR) algorithm for the detection of hypervascular liver lesions. METHODS: Thirty liver phantoms with or without simulated hypervascular lesions were scanned with a 320-slice CT scanner with control-dose (40 mAs) and reduced-dose (30 and 20 mAs) settings. Control-dose images were reconstructed with filtered back projection (FBP), and reduced-dose images were reconstructed with FBP and a hybrid IR algorithm. Objective image noise and the lesion to liver contrast-to-noise ratio (CNR) were evaluated quantitatively. Images were interpreted independently by 2 blinded radiologists, and jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis was performed. RESULTS: Hybrid IR images with reduced-dose settings (both 30 and 20 mAs) yielded significantly lower objective image noise and higher CNR than control-dose FBP images (P < .05). However, hybrid IR images with reduced-dose settings had lower JAFROC1 figure of merit than control-dose FBP images, although only the difference between 20 mAs images and control-dose FBP images was significant for both readers (P < .01). CONCLUSIONS: An aggressive reduction of the radiation dose would impair the detectability of hypervascular liver lesions, although objective image noise and CNR would be preserved by a hybrid IR algorithm. KEY POINTS: • A half-dose scan with a hybrid iterative reconstruction preserves objective image quality. • A hybrid iterative reconstruction algorithm does not improve diagnostic performance. • An aggressive dose reduction would impair the detectability of low-contrast lesions.

Preoperative staging of endometrial cancer using reduced field-of-view diffusion-weighted imaging: a preliminary study.

OBJECTIVES: To compare the image quality and diagnostic performance of reduced field-of-view (rFOV) versus conventional full field-of-view (fFOV) diffusion-weighted (DW) imaging of endometrial cancer. METHODS: Fifty women with endometrial cancer underwent preoperative rFOV and fFOV DW imaging. Two radiologists compared the image qualities of both techniques, and five radiologists assessed superficial and deep myometrial invasion using both techniques. The statistical analysis included the Wilcoxon signed-rank test and paired t-test for comparisons of image quality and mean diagnostic values. RESULTS: Distortion, tumour delineation, and overall image quality were significantly better with rFOV DW imaging, compared to fFOV DW imaging (P < 0.05); however, the former was inferior in noise (P < 0.05). Regarding superficial invasion, the mean accuracies of the techniques did not differ statistically (rFOV, 58.0% versus fFOV, 56.0%; P = 0.30). Regarding deep myometrial invasion, rFOV DW imaging yielded significantly better mean accuracy, specificity, and positive predictive values (88.4%, 97.8%, and 91.7%, respectively), compared with fFOV DW imaging (84.8%, 94.1%, and 77.4%, respectively; P = 0.009, 0.005, and 0.011, respectively). CONCLUSIONS: Compared with fFOV DW imaging, rFOV DW imaging yielded less distortion, improved image quality and, consequently, better diagnostic performance for deep myometrial invasion of endometrial cancer. KEY POINTS: • rFOV DWI yields better assessment of deep myometrial invasion in endometrial cancer. • rFOV DWI could not sufficiently evaluate superficial invasion in endometrial cancer. • Distortion, tumour delineation, and overall image quality were improved with rFOV DWI.

Is cardiac and hepatic iron status assessed by MRI T2* associated with left ventricular function in patients with idiopathic cardiomyopathy?

Excess accumulation of iron in the heart is known to aggravate cardiac function in some cases of genetic and acquired iron overload. We investigated the possible association between cardiac function and iron content in the heart and liver, estimated non-invasively by T2 star (T2*)-weighted magnetic resonance (MR) imaging among patients with cardiomyopathy. MR images were acquired on a 3.0 T MR imaging system using an 8-channel phased-array cardiac coil. Average T2* values of the heart were estimated at regions of interest that were located on short axis mid-ventricular slices positioned at the cardiac septum. In total, 82 patients were enrolled: 48 patients with dilated cardiomyopathy (DCM), 16 patients with hypertrophic cardiomyopathy (HCM), and 18 patients without apparent cardiovascular abnormalities. Cardiac T2* values were lower in the DCM group (median 18.6 ms) than in the HCM (22.0 ms) and control (21.4 ms) groups, although hepatic T2* values did not differ significantly across the groups. Among the whole population, the highest cardiac T2* tertile (≥21.2 ms) was significantly negatively associated with a low left ventricular ejection fraction (LVEF) of <50 %, and this association retained statistical significance after adjustment for sex, age, renal function, hemoglobin and hepatic T2*. Among DCM patients, both hemoglobin and cardiac T2* were selected as parameters that were, respectively, negatively and positively, associated with LVEF (P < 0.05). DCM patients with lower cardiac T2*, and thus higher iron content, were found to have lower LVEF. The possibility that cardiac iron overload may have a role in reducing the systolic cardiac function in DCM patients who do not have systemic iron overload requires further investigation in the future.

Magnetic resonance imaging findings in atypical polypoid adenomyoma.

OBJECTIVES: This article describes magnetic resonance imaging (MRI) findings in 3 cases of atypical polypoid adenomyoma (APAM). METHODS: Clinical and MRI manifestations of 3 patients with APAM were evaluated. High b value diffusion-weighted and dynamic contrast-enhanced images were performed. The size, shape, site of origin, and signal intensity (SI) of MRI findings were evaluated. RESULTS: All patients (age range, 37-47 years; mean age, 40 years) had a chief complaint of atypical genital bleeding with no history of pregnancy. In 2 cases, cytology of the endometrium was positive, and pathological analysis of curettage specimens indicated endometrioid adenocarcinoma. The MRI revealed an endometrial polypoid mass arising from the upper corpus (50%) or lower uterine segment (50%). Except for 1 tumor that seemed to invade the myometrium of the uterine wall due to its irregular margin, all tumors were well circumscribed. On T2-weighted MRI scans, the SI of the tumor was homogenous and marginally hyperintense, and contained markedly hyperintense cystic foci. On T1-weighted images, all the tumors were isointense relative to the myometrium, and in 1 case, a number of cystic foci showed high SIs. In a dynamic contrast-enhanced study, solid portions other than the cystic foci showed contrast enhancement in the arterial phase and demonstrated a washout pattern or plateau pattern in the late phase. All tumors demonstrated high SIs on diffusion-weighted images. CONCLUSIONS: Differentiating APAM from other malignant polypoid uterine endometrial tumors may still pose difficulties, especially when the tumor seems to invade the myometrium on MRI. Comprehensive clinical information about the patient including age, pathological assessment of the endometrium, and MRI findings should be essential to provide indication for a diagnosis of APAM.

A case of gastric-type adenocarcinoma of the uterine cervix associated with lobular endocervical glandular hyperplasia: radiologic-pathologic correlation.

Gastric-type adenocarcinoma (GAS) of the uterine cervix is a recently defined subtype of mucinous adenocarcinoma. GAS is proposed to include minimal deviation adenocarcinoma (MDA) as a very well-differentiated form and has been suggested to arise from lobular endocervical glandular hyperplasia (LEGH). We report the magnetic resonance imaging (MRI) findings of a GAS associated with LEGH. On MRI, the LEGH component was detected as multiple cystic lesions arranged in a "cosmos pattern", while the GAS was depicted as a predominantly solid lesion containing obvious adenocarcinoma and MDA components, which appeared as mass-like and infiltrative components, respectively. The GAS exhibited tiny cysts on three-dimensional T2-weighted images, high intensity on diffusion-weighted images mostly due to T2 shine-through effect according to apparent diffusion coefficient (ADC) map, and reticular enhancement on dynamic contrast-enhanced MRI, which reflected numerous dilated glandular structures of the tumor. Low ADC was only observed at the deepest invasion front of the obvious adenocarcinoma component. Our case suggests that the MRI features of GAS vary depending on the tumor's histological components, and it is important to be aware of these imaging features when evaluating LEGH on MRI.

High-dose-rate interstitial brachytherapy in combination with androgen deprivation therapy for prostate cancer: are high-risk patients good candidates?

BACKGROUND AND PURPOSE: To evaluate the effectiveness of high-dose-rate interstitial brachytherapy (HDR-ISBT) as the only form of radiotherapy for high-risk prostate cancer patients. PATIENTS AND METHODS: Between July 2003 and June 2008, we retrospectively evaluated the outcomes of 48 high-risk patients who had undergone HDR-ISBT at the National Hospital Organization Osaka National Hospital. Risk group classification was according to the criteria described in the National Comprehensive Cancer Network (NCCN) guidelines. Median follow-up was 73 months (range 12-109 months). Neoadjuvant androgen deprivation therapy (ADT) was administered to all 48 patients; 12 patients also received adjuvant ADT. Maximal androgen blockade was performed in 37 patients. Median total treatment duration was 8 months (range 3-45 months). The planned prescribed dose was 54 Gy in 9 fractions over 5 days for the first 13 patients and 49 Gy in 7 fractions over 4 days for 34 patients. Only one patient who was over 80 years old received 38 Gy in 4 fractions over 3 days. The clinical target volume (CTV) was calculated for the prostate gland and the medial side of the seminal vesicles. A 10-mm cranial margin was added to the CTV to create the planning target volume (PTV). RESULTS: The 5-year overall survival and biochemical control rates were 98 and 87 %, respectively. Grade 3 late genitourinary and gastrointestinal complications occurred in 2 patients (4 %) and 1 patient (2 %), respectively; grade 2 late genitourinary and gastrointestinal complications occurred in 5 patients (10 %) and 1 patient (2 %), respectively. CONCLUSION: Even for high-risk patients, HDR-ISBT as the only form of radiotherapy combined with ADT achieved promising biochemical control results, with acceptable late genitourinary and gastrointestinal complication rates.

Clinical application of bladder MRI and the Vesical Imaging-Reporting and Data System.

Diagnostic work-up and risk stratification in patients with bladder cancer before and after treatment must be refined to optimize management and improve outcomes. MRI has been suggested as a non-invasive technique for bladder cancer staging and assessment of response to systemic therapy. The Vesical Imaging-Reporting And Data System (VI-RADS) was developed to standardize bladder MRI image acquisition, interpretation and reporting and enables accurate prediction of muscle-wall invasion of bladder cancer. MRI is available in many centres but is not yet recommended as a first-line test for bladder cancer owing to a lack of high-quality evidence. Consensus-based evidence on the use of MRI-VI-RADS for bladder cancer care is needed to serve as a benchmark for formulating guidelines and research agendas until further evidence from randomized trials becomes available.

Reduction of interpatient variability of arterial enhancement using a new bolus tracking system in 320-detector computed tomographic coronary angiography.

OBJECTIVE: To investigate the effect of a new bolus tracking system on interpatient variability of aortic and coronary enhancement compared with the conventional system in 320-detector computed tomographic (CT) coronary angiography (CTCA). METHODS: Sixty-four patients who underwent CTCA were assigned to 1 of 2 protocols. In group A (n = 32), 7 seconds after triggering (150-Hounsfield unit [HU] threshold) in the ascending aorta, a CT scan was performed. In group B (n = 32), 2 thresholds were set in the ascending aorta. After the first triggering (100 HU threshold), the patient was instructed to take a breath and hold it. Approximately 3 seconds after the second triggering (300 HU threshold), a CT scan was started automatically. RESULTS: There were no significant differences in the mean CT attenuation for the ascending aorta between the 2 groups (P = 0.61), whereas the standard deviation of the CT attenuation in group B was significantly smaller than that in group A (P = 0.02). CONCLUSIONS: The use of a 2-threshold setting in the new bolus tracking technique could reduce interpatient variability more than a protocol using a single threshold in CTCA.

Initial experience with adaptive iterative dose reduction 3D to reduce radiation dose in computed tomographic urography.

OBJECTIVE: This study aimed to investigate the feasibility of low-dose computed tomographic (CT) urography with adaptive iterative dose reduction 3D (AIDR 3D). METHODS: Thirty patients underwent routine-dose CT scans with filtered back projection and low-dose CT scans with AIDR 3D in the excretory phase of CT urography. Visual evaluations were performed with respect to internal image noises, sharpness, streak artifacts, and diagnostic acceptability. Quantitative measures of the image noise and radiation dose were also obtained. All results were compared on the basis of body mass index (BMI). RESULTS: At visual evaluations, streak artifacts in the urinary bladder were statistically weaker on low-dose CT than on routine-dose CT in the axial and coronal images (P < 0.001 and P = 0.01). There were no statistical differences between routine-dose CT and low-dose CT for other evaluation items in all structures. Image noise was lower on low-dose CT than on routine-dose CT in all structures (P < 0.001). The overall average dose reduction was 45.0% in all patients. The average dose reduction for the patients with a BMI of less than 20, 20 to 25, greater than 25 kg/m was 43.0%, 44.0%, and 49.6%, respectively. CONCLUSION: Low-dose CT urography with AIDR 3D allows 45% reduction of radiation dose without degenerating of the image quality in the excretory phase independently to a BMI.

Low-dose computed tomographic urography using adaptive iterative dose reduction 3-dimensional: comparison with routine-dose computed tomography with filtered back projection.

OBJECTIVE: The aim of this study was to evaluate the image quality of low-dose computed tomographic (CT) urography using adaptive iterative dose reduction 3-dimensional (AIDR 3D) compared with routine-dose CT using filtered back projection (FBP). METHODS: Thirty patients underwent low- and routine-dose CT scans in the nephrographic and excretory phases of CT urography. Low-dose CT was reconstructed with AIDR 3D, and routine-dose CT was reconstructed with FBP. In quantitative analyses, image noises were measured on the renal cortex, aorta, retroperitoneal fat, and psoas muscle in both CT scans and compared. Qualitative analyses of the urinary system were performed in both CT scans and compared. These results were compared on the basis of the body mass index (BMI) of the patients. The CT dose index (CTDIvol) was measured, and the dose reduction was calculated. RESULTS: In quantitative analyses, image noises in all organs on low-dose CT were less than those on routine-dose CT in both phases independently of the patient's BMI. There were no statistical differences between low- and routine-dose CT for diagnostic acceptability on all urinary systems in both phases independently of the patient's BMI. The average CTDIvol on routine-dose CT was 14.5 mGy in the nephrographic phase and 9.2 mGy in the excretory phase. The average CTDIvol on low-dose CT was 4.2 mGy in the nephrographic phase and 2.7 mGy in the excretory phase. CONCLUSIONS: Low-dose CT urography using AIDR 3D can offer diagnostic acceptability comparable with routine-dose CT urography with FBP with approximately 70% dose reduction.

Impact of adaptive iterative dose reduction (AIDR) 3D on low-dose abdominal CT: comparison with routine-dose CT using filtered back projection.

BACKGROUND: While CT is widely used in medical practice, a substantial source of radiation exposure is associated with an increased lifetime risk of cancer. Therefore, concerns to dose reduction in CT examinations are increasing and an iterative reconstruction algorithm, which allow for dose reduction by compensating image noise in the image reconstruction, has been developed. PURPOSE: To investigate the performance of low-dose abdominal CT using adaptive iterative dose reduction 3D (AIDR 3D) compared to routine-dose CT using filtered back projection (FBP). MATERIAL AND METHODS: Fifty-eight patients underwent both routine-dose CT scans using FBP and low-dose CT scans using AIDR 3D in the abdomen. The image noise levels, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) of the aorta, portal vein, liver, and pancreas were measured and compared in both scans. Visual evaluations were performed. The volume CT dose index (CTDIvol) was measured. RESULTS: Image noise levels on low-dose CT images using AIDR 3D were significantly lower than, or not significantly different from, routine-dose CT images using FBP in reviewing the data on the basis of all patients and the three BMI groups. SNRs and CNRs on low-dose CT images using AIDR 3D were significantly higher than, or not significantly different from, routine-dose CT images using FBP in reviewing the data on the basis of all patients and the three BMI groups. In visual evaluation of the images, there were no statistically significant differences between the scans in all organs independently of BMI. The average CTDIvol at routine-dose and low dose CT was 21.4 and 10.8 mGy, respectively. CONCLUSION: Low-dose abdominal CT using AIDR 3D allows for approximately 50% reduction in radiation dose without a degradation of image quality compared to routine-dose CT using FBP independently of BMI.

[Application of N-isopropyl-p-[123I] iodoamphetamine quantification of regional cerebral blood flow using iterative reconstruction methods: selection of the optimal reconstruction method and optimization of the cutoff frequency of the preprocessing filter].

In cerebral blood flow tests using N-Isopropyl-p-[123I] Iodoamphetamine "I-IMP, quantitative results of greater accuracy than possible using the autoradiography (ARG) method can be obtained with attenuation and scatter correction and image reconstruction by filtered back projection (FBP). However, the cutoff frequency of the preprocessing Butterworth filter affects the quantitative value; hence, we sought an optimal cutoff frequency, derived from the correlation between the FBP method and Xenon-enhanced computed tomography (XeCT)/cerebral blood flow (CBF). In this study, we reconstructed images using ordered subsets expectation maximization (OSEM), a method of successive approximation which has recently come into wide use, and also three-dimensional (3D)-OSEM, a method by which the resolution can be corrected with the addition of collimator broad correction, to examine the effects on the regional cerebral blood flow (rCBF) quantitative value of changing the cutoff frequency, and to determine whether successive approximation is applicable to cerebral blood flow quantification. Our results showed that quantification of greater accuracy was obtained with reconstruction employing the 3D-OSEM method and using a cutoff frequency set near 0.75-0.85 cycles/cm, which is higher than the frequency used in image reconstruction by the ordinary FBP method.