Yoshifumi Narumi

Clinical utility of apparent diffusion coefficient (ADC) values in patients with prostate cancer: Can ADC values contribute to assess the aggressiveness of prostate cancer?

To retrospectively evaluate the relationship between apparent diffusion coefficient (ADC) values and Gleason score (GS) in prostate cancer.

High-resolution MR lymphography using ultrasmall superparamagnetic iron oxide (USPIO) in the evaluation of axillary lymph nodes in patients with early stage breast cancer: preliminary results

BackgroundThe purpose of this study was to examine the utility of high-resolution magnetic resonance (MR) lymphography using ultrasmall superparamagnetic iron oxide (USPIO) in the evaluation of axillary lymph nodes in patients with early stage breast cancer.MethodsTen women with breast cancer without swollen axillary lymph nodes were enrolled in this study. High-resolution MR lymphography was performed 24xa0h after administration of USPIO. On the MR examination, a 3-inch surface coil was placed on the sentinel lymph node (SLN) parts as defined by a radioisotope (RI) scintigraphy method, and T2*-weighted (T2*W) and T1-weighted (T1W) images were obtained. Detected nodes were differentiated as normal or diseased nodes by the enhancement patterns. The day after MR examination, SLN biopsy (SNB) was performed. The imaging results were compared to the histopathologic findings.ResultsOn MR images, the mean number of detectable nodes was 7.9 per patient. Eight patients who histopathologically had no metastatic lymph nodes were diagnosed as nonmetastatic and two patients who had 3- and 6-mm metastatic areas in the node, respectively, were diagnosed as metastatic preoperatively. No side effects were noted.ConclusionsHigh-resolution MR lymphography using USPIO enabled us to obtain good axillary lymph node evaluation results. These results suggest that this method of imaging may contribute to better preoperative lymph node staging.

Feasibility of low-volume injections of contrast material with a body weight-adapted iodine-dose protocol in 320-detector row coronary CT angiography.

RATIONALE AND OBJECTIVESnTo investigate the feasibility of low-volume injections of contrast material with a body weight-adapted iodine-dose protocol in computed tomography coronary angiography (CTCA) using a 320-detector row scanner.nnnMATERIALS AND METHODSnNinety-eight patients who underwent CTCA in a single heartbeat with electrocardiogram-gating were divided into two groups, receiving 0.8 mL/kg of contrast material injected at a fixed duration of 12 seconds (A; n = 48) or 0.7 mL/kg of contrast material injected at a fixed duration of 10 seconds (B; n = 50); all patients then received 20 mL of saline. Contrast densities were assessed for the ascending aorta, left ventricle, right coronary artery (RCA), and left main coronary artery (LMA).nnnRESULTSnThe mean flow rate was 4.00 + or - 0.56 mL/second in group A and 4.06 + or - 0.57 mL/second in group B (P = .51). There were no significant differences in the mean enhancement values of the ascending aorta, LMA and proximal RCA between the two groups. Also, there was no significant difference between the mean enhancement values at the three different levels of the RCA (proximal, middle, and distal segments) (group A; P = .27, group B; P = .07).nnnCONCLUSIONnThe use of 0.7 mL/kg of contrast material injected at a fixed duration of 10 seconds was feasible for CTCA using 320-detector row CT, with a sufficient and reliable contrast enhancement in the ascending aorta and coronary artery.

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.

Evaluation of axillary lymph nodes by diffusion-weighted MRI using ultrasmall superparamagnetic iron oxide in patients with breast cancer: Initial clinical experience

To investigate the diagnostic performance and clinical feasibility of diffusion‐weighted magnetic resonance imaging (MRI) using ultrasmall superparamagnetic iron oxide (USPIO) in the evaluation of axillary lymph nodes (ALNs) in patients with breast cancer.

Pneumatosis cystoides intestinalis: CT findings

Two patients with primary pneumatosis cystoides intestinalis are presented. In both cases, the sigmoid colon was involved and there were no major complications. On computed tomography (CT), at lung window settings, the gas cysts in the colonic wall were clearly delineated. CT was useful in confirming the intramural gas cysts in patients with primary pneumatosis cystoides intestinalis.

MR features of various histological grades of small hepatocellular carcinoma

Twenty small hepatocellular carcinomas (HCCs) <20 mm in diameter in 18 patients, detected by MRI, were surgically resected and histologically confirmed. Quantitative analysis of signal intensity on MR images was performed with 14 homogeneous lesions. In the five grade I HCCs, T1-weighted SE sequences provided significantly higher mean tumor-liver contrast and contrast-to-noise ratio (C/N) than T2-weighted SE sequences (p < 0.01). However, in the other nine HCCs (grade I + II or greater), T2-weighted SE sequences had significantly higher mean tumor-liver contrast and C/N values than T1-weighted SE sequences (p < 0.001). The T2-weighted SE sequences appear superior to T1-weighted SE sequences for grade I + II or greater HCC detection, whereas T1-weighted SE sequences are valuable in the detection of grade I HCCs.

Guidelines on the use of iodinated contrast media in patients with kidney disease 2012: digest version

Open image in new window What is the definition of CIN? n nAnswer: n nCIN is defined as an increase in serum creatinine (SCr) levels by ≥0.5 mg/dL or ≥25 % from baseline within 72 h after a contrast radiography using iodinated contrast media. nOpen image in new window n n nBecause the risk for developing CIN increases as kidney function decreases, it is important to evaluate kidney function on the basis of the latest SCr levels prior to contrast radiography. According to the classification of the severity of CKD, which is based on the cause, GFR, and presence and severity of albuminuria (Table 1) [1], patients with a GFR of <60 mL/min/1.73 m2 (G3a–G5) are considered to have CKD in this guideline. In another words, CKD is also diagnosed in patients with a GFR of ≥60 mL/min/1.73 m2 and albuminuria, in the present guidelines only patients with a GFR of <60 mL/min/1.73 m2 are defined as having CKD. n n nTable 1 nClassification of severity of CKD (2012) n n n n nOpen image in new window n n n nRisks of ESKD requiring dialysis or transplantation, and risks for cardiovascular diseases such as stroke, myocardial infarction, and heart failure are coded with colors ranging from green (lowest), yellow, orange and red (highest) n nCKD chronic kidney disease, Cr creatinine, ESKD end-stage kidney disease, GFR glomerular filtration rate n nAdapted from KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Inter Suppl. 2013;3:19–62 [1], with permission from Nature Publishing Group., modified for Japanese patients n n n n nThe following formula is used to calculate estimated GFR (eGFR). nOpen image in new window n n nCIN is a form of acute kidney injury (AKI) that occurs after exposure to iodinated contrast media, and is diagnosed on the basis of reducing kidney function after contrast radiography when other causes such as cholesterol embolism are ruled out. AKI due to CIN is generally reversible. Usually, SCr levels increase to a peak 3–5 days after onset, and return to normal in 7–14 days. However, kidney injury may worsen to the point that hemodialysis is required in some patients. n nThe criteria for the diagnosis of CIN used in clinical research of this condition vary among studies. The minimum increment of SCr levels that defined CIN included 0.5 mg/dL, 1.0 mg/dL, and 25 % or 50 % from baseline, and the duration of monitoring for CIN included 24 h, 48 h, 72 h, 4 days, and 7 days after contrast radiography. The most commonly used criteria for CIN in clinical research is an increase in SCr levels by ≥0.5 mg/dL or ≥25 % from baseline within 72 h after contrast radiography. However, physicians in the clinical setting should not wait for 72 h, and should start close monitoring of SCr levels from an early stage when CIN is suspected. The incidence of CIN, and clinical characteristics such as patients’ baseline kidney function, vary depending on the criteria used for diagnosis. Standardized diagnostic criteria are necessary to promote clinical research of this condition and develop preventive procedures. nOpen image in new window n nOpen image in new window

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.

MAGNETIC RESONANCE IMAGING-HISTOLOGIC CORRELATION OF SMALL HEPATOCELLULAR CARCINOMAS AND ADENOMATOUS HYPERPLASIAS

RATIONALE AND OBJECTIVES.Hepatocellular carcinomas (HCCs) usually consist of components of different histologic grade. Using surgically resected specimens, the authors obtained high-resolution magnetic resonance (MR) images and studied the relationship between histologic grade of HCCs and MR signal intensity. METHOD.In vitro MRI was performed on 15 small (less than 20-mm diameter) HCCs and 2 patients with adenomatous hyperplasia (AH) within 1 hour of surgical resection. In these 17 lesions, 24 macroscopic nodular components corresponding to MR images were recognized pathologically. The difference in MR signal intensity was examined by using tumor/phantom (T/P) signal-intensity ratio. In addition, the correlations between signal intensity on MRI and histologic criteria for grading HCC were studied. RESULTS.On T2-weighted images, grade II HCCs had significantly greater T/P values than grade I HCCs (P < .01). There is the correlation (r = .88, P < .001) between nucleocytoplasmic (N/C) ratio and signal intensity of small HCCs and AHs on T2-weighted images. CONCLUSION.The N/C ratio is an important factor relating the signal intensity to the histologic grade of these lesions on T2-weighted images.