Hiroshi Juri

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.

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.

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/m2 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.

Detection of bladder cancer: comparison of low-dose scans with AIDR 3D and routine-dose scans with FBP on the excretory phase in CT urography

OBJECTIVE To prospectively compare the detection of bladder cancer between low-dose scans with adaptive iterative dose reduction three dimensional projection (AIDR 3D) and routine-dose scans with filtered back projection (FBP) on the excretory phase (EP) in CT urography. METHODS 42 patients were included. Routine- and low-dose EP were performed in each patient. Routine-dose images were reconstructed with FBP, and low-dose images were reconstructed with AIDR 3D. Two radiologists scored confidence levels for the presence or absence of bladder cancer using a 5-point scale. The CT dose index of each EP was measured, and the dose reduction was calculated. RESULTS Sensitivity, specificity and accuracy were 86.4%, 95.0% and 90.5% on routine-dose scans and were 86.4%, 90.0% and 88.1% on low-dose scans, respectively. There was no significant difference (p; not significant, 1.00 and 1.00, respectively). The average CT dose index was 8.07 and 2.63 mGy on routine- and low-dose scans, and the ratio of dose reduction was 67.6%. CONCLUSION The detection of bladder cancer on low-dose scans with AIDR 3D is almost equal to that on routine-dose scans with FBP on the EP, with nearly 70% dose reduction. ADVANCES IN KNOWLEDGE Using AIDR 3D, the radiation dose may be reduced on the EP in CT urography for the detection of bladder cancer.

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

AbstractObjectivesTo investigate the diagnostic performance of reduced-dose CT with a hybrid iterative reconstruction (IR) algorithm for the detection of hypervascular liver lesions.MethodsThirty 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.ResultsHybrid 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).ConclusionsAn 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.

Pathological findings of uterine tumors preoperatively diagnosed as red degeneration of leiomyoma by MRI

PurposeVenous infarction of a leiomyoma is known as red degeneration of leiomyoma (RDL) and can be a cause of acute abdomen. Although magnetic resonance imaging (MRI) is the only modality that can depict the inner condition of a leiomyoma, the typical MR findings of RDL are sometimes identified incidentally even in asymptomatic patients. The purpose of this study is to clarify common pathological findings of uterine tumors preoperatively diagnosed as RDL by MRI.MethodsWe diagnosed 28 cases of RDL by MRI from March 2007 to April 2015. The ten lesions subjected to pathological analysis after resection were included in the study and reviewed by a gynecological pathologist. The average time from MRI to operation was 4.7 months.ResultsThe typical beefy-red color was not observed on the cut surface of the tumor except in one tumor resected during the acute phase. All lesions diagnosed as RDL by MRI had common pathological findings consistent with red degeneration of leiomyoma, including coagulative necrosis. Other common pathological features of RDL besides extensive coagulative necrosis appear to be a lack of inflammatory cell infiltrate or hemorrhage in the entire lesion.ConclusionsAlthough RDL is known to cause acute abdomen, its typical MR findings can be observed even in asymptomatic patients in a condition that manifests long after red degeneration. The characteristic pathological findings in both the acute phase and the chronic phase that we found in this study, along with radiology reports, will be helpful references for gynecologists and pathologists in suspecting a history of red degeneration and confirming the diagnosis.

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.

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.

Are there any metastases to the chest in non-muscle-invasive bladder cancer patients on follow-up computed tomography?

PurposeThe purpose of the study was to retrospectively determine whether there are metastases to the chest in patients with primary non-muscle-invasive urothelial carcinoma in the bladder on the follow-up computed tomography (CT).MethodsWe analyzed 328 patients with follow-up chest CT for urothelial carcinoma of the bladder diagnosed between January 2004 and September 2013. We divided patients into four groups: Ta (n = 74), T1 (n = 78), carcinoma in situ (CIS, n = 25), and ≥ T2 (n = 151). We used the chest CT to determine whether there were positive findings of metastasis. Univariate and multivariate analyses were achieved using categories of T stage, histological grade, multifocal lesions, and recurrence.ResultsOn univariate analysis, there were significant differences on T stage (p < 0.001) and histological grade (p = 0.001), and there was no significant difference on multifocal lesions (p = 0.11) and recurrence (p = 0.34). Positive findings of metastases were observed in 1.4% (1/74) of the Ta patients, 0% (0/78) of the T1 patients, 8.0% (2/25) of the patients with carcinoma in situ (CIS), and 27.2% (41/151) of the ≥ T2 patients (p < 0.001). On multivariate analysis, T staging was independent variable for positive findings of metastasis (Odds ratio; 2.84, 95% Confidence Interval; 1.65–4.89). In contrast, histological grade, multifocal lesions, and recurrence were not independent variables.ConclusionsT stage would affect to metastasis to the chest. It might be appropriate to omit chest CT in patients with Ta or T1 without upstaging in the course of follow-up. We may suggest that the follow-up chest CT in patients with CIS.

Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system

Objective To prospectively evaluate the ability of CT urography with a low-dose multi-phasic excretory phase for opacification of the urinary system. Materials and methods Thirty-two patients underwent CT urography with low-dose multi-phasic s using adaptive iterative dose reduction 3D acquired at 5-, 10-, and 15-minute delays. Opacification scores of the upper urinary tracts and the urinary bladder were assigned for each excretory phase by two radiologists, who recorded whether adequate (>75%) or complete (100%) opacification of the upper urinary tract and urinary bladder was achieved in each patient. Adequate and complete opacification rates of the upper urinary tracts and the urinary bladder were compared among three excretory phases and among combined multi-phasic excretory phases using Cochrans Q test. Results There was no significant difference among three excretory phases with 5-, 10-, and 15-minute delays in adequate (56.3, 43.8, and 63.5%, respectively; P = 0.174) and complete opacification rates (9.3, 15.6, and 18.7%, respectively; P = 0.417) of the upper urinary tracts. Combined tri-phasic excretory phases significantly improved adequate and complete opacification rates to 84.4% and 43.8%, respectively (P = 0.002). In contrast, there were significant differences among three excretory phases for the rate of adequate (31.3, 84.4, and 93.8%, respectively; P<0.001) and complete opacification (21.9, 53.1, and 81.3%, respectively; P<0.001) of the urinary bladder. Multi-phasic excretory phases did not improve these rates because opacification was always better with a longer delay. Conclusion Although multi-phasic acquisition of excretory phases is effective at improving opacification of the upper urinary tracts, complete opacification is difficult even with tri-phasic acquisition.