Ring-shaped lateral ventricular nodules: an incidental finding on brain magnetic resonance imaging.

INTRODUCTION: We have occasionally seen ring-shaped lateral ventricular nodules <1 cm in diameter during routine brain magnetic resonance imaging (MRI). We investigated retrospectively clinical and MRI findings of the nodules. MATERIALS AND METHODS: Review of radiological records was performed for 39,607 patients who underwent brain MRI between January 2001 and April 2008. Nodules were assessed for number, location, shape, and signal intensity, which was determined based on the range of signal intensity from gray to white matter on T1- and T2-weighted imaging. Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging (DWI), contrast enhancement characteristics, and serial MRI changes of nodules were assessed when available. RESULTS: Nine of 39,607 patients (0.023%) showed the nodules. No symptoms associated with the nodules. Among the nine patients, 11 nodules were identified (one nodule in seven patients (77.8%) and two nodules in two patients (22.2%)). Location was limited to the roof of the body for six nodules (54.5%) and the frontal horn for five patients (45.5%). All nodules (100%) were round and isointense on T1- and T2-weighted imaging. On FLAIR imaging of eight nodules, six (75%) were hyperintense, and two (25%) were isointense. On DWI of seven nodules, all nodules (100%) were isointense. None of seven nodules (0%) examined using postcontrast MRI showed enhancement. None of eight nodules (0%) examined using serial MRI (range, 4-60 months) showed changes in morphology over time. CONCLUSION: These nodules were incidentally encountered and shared similar MRI features. Although pathological confirmation was lacking in our cases, these nodules may be of nonaggressive nature.

Integrated FDG-PET/CT compared with intravenous contrast-enhanced CT for evaluation of metastatic regional lymph nodes in patients with resectable early stage esophageal cancer.

OBJECTIVE: To assess whether integrated fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can improve the diagnostic accuracy of metastatic regional lymph nodes (LNs) in esophageal cancer compared with contrast enhanced CT (CECT). METHODS: We examined 180 consecutive patients with esophageal cancer by integrated PET/CT between April 2006 and March 2007. Eighteen patients (M:F 14:4) underwent radical esophagectomy after evaluations by PET/CT and CECT of 5-7-mm-thick slices 70-80 s after injection. Regional LNs of esophageal cancer were retrospectively reviewed on CECT images by two blinded evaluators on the basis of the following cutoff sizes: 7 mm for all regional LNs (Protocol A), 10 mm for paratracheal LNs (Protocol B), and 7 mm for others. In addition, the maximum standardized uptake value (SUVmax) on PET/CT was evaluated for positive uptake by LNs. RESULTS: Of 210 LNs excised at surgery, 25 were positive and 185 were negative for metastasis at pathology. The PET/CT images identified 15 true-positive and 184 true-negative LNs, whereas CECT identified 15 true positives and 176 true negatives in Protocol A, and 14 true positives and 180 true negative in Protocol B. The sensitivity, specificity, accuracy, positive, and negative predictive values of PET/CT were respectively 60.0%, 99.5%, 94.8%, 93.8%, and 94.8%, whereas those of CECT were 60.0%, 95.1%, 91.0%, 62.5%, and 94.6% (Protocol A) and 56.0%, 97.3%, 92.4%, 73.7%, and 94.2% (Protocol B). A comparison of the two CECT protocols revealed fewer false-positive LNs in Protocol B, but slightly lower sensitivity in Protocol B than in Protocol A. Substantial numbers of false-positive LNs were determined by CECT in the paratracheal regions (6 of 9, 66.7%) and CECT revealed central necrosis in 4 of 15 (26.7%) true-positive LNs > 1.8 cm. The mean SUVmax on PET/CT was 2.9 (range 1.7-5.5) in true-positive LNs. The smallest LN metastasis detectable by PET/CT was 6 mm. CONCLUSIONS: Integrated PET/CT improves the PPV of regional LNs when compared with CECT.

Adrenal masses: the value of additional fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in differentiating between benign and malignant lesions.

OBJECTIVE: To investigate whether integrated fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) can differentiate benign from adrenal malignant lesions on the basis of maximum standardized uptake value (SUV(max)), tumor/liver (T/L) SUV(max) ratio, and CT attenuation value (Hounsfield Units; HU) of unenhanced CT obtained from FDG-PET/CT data. METHODS: We studied 30 patients with 35 adrenal lesions (16 adrenal benign lesions, size 16 +/- 5 mm, in 15 patients; and 19 adrenal malignant lesions, 24 +/- 12 mm, in 15 patients) who had confirmed primary malignancies (lung cancer in 23 patients, lymphoma in 2, esophageal cancer in 2, hypopharyngeal cancer in 1, prostate cancer in 1, and 1 patient in whom lesions were detected at cancer screening). All patients underwent PET/CT at 1 h post FDG injection. Diagnosis of adrenal malignant lesions was based on interval growth or reduction after chemotherapy. An adrenal mass that remained unchanged for over 1 year was the standard used to diagnose adrenal benign lesions. Values of FDG uptake and CT attenuation were measured by placing volumetric regions of interest over PET/CT images. Adrenal uptake of SUV(max) >/= 2.5 was considered to indicate a malignant lesion; SUV(max) < 2.5 was considered to indicate a benign lesion. In further analysis, 1.8 was employed as the threshold for the T/L SUV(max) ratio. Unenhanced CT obtained from PET/CT data was considered positive for adrenal malignant lesions based on a CT attenuation value >/= 10 HU; lesions with a value < 10 HU were considered adrenal benign lesions. Mann-Whitney's U test was used for statistical analyses. RESULTS: SUV(max) in adrenal malignant lesions (7.4 +/- 3.5) was higher than that in adrenal benign lesions (2.1 +/- 0.5, p < 0.05). The CT attenuation value of adrenal malignant lesions (27.6 +/- 11.9 HU) was higher than that of adrenal benign lesions (10.1 +/- 12.3 HU, p < 0.05). In differentiating between adrenal benign and malignant lesions, a CT threshold of 10 HU corresponded to a sensitivity of 57%, specificity of 94%, accuracy of 74%, positive predictive value of 92% and negative predictive value of 65%. An SUV(max) cut-off value of 2.5 corresponded to a sensitivity of 89%, specificity of 94%, accuracy of 91%, positive predictive value of 94% and negative predictive value of 88%. The T/L SUV(max) ratio was 1.0 +/- 0.2 for adrenal benign lesions and 4.5 +/- 3.0 for adrenal malignant lesions. And T/L SUV(max) ratio cut-off value of 1.8 corresponded to a sensitivity of 85%, specificity of 100%, accuracy of 91%, positive predictive value of 100% and negative predictive value of 83%. CONCLUSIONS: FDG-PET/CT with additional SUV(max) analysis improves the diagnostic accuracy of adrenal lesions in cancer patients.

Hypervascular hepatocellular carcinoma: Combined dynamic MDCT and SPIO-enhanced MRI versus combined CTHA and CTAP.

AIM: Recently, many diagnostic modalities have been developed for the detection of hepatocellular carcinoma (HCC). Of these, a less invasive and more accurate diagnostic procedure is desirable. This study was undertaken to compare combined dynamic multidetector row helical computerized tomography (MDCT) and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) with combined CT hepatic arteriography (CTHA) and CT during arterial portography (CTAP) for the detection of hypervascular HCC. METHODS: Forty-eight patients with 56 pathologically proved hypervascular HCCs (less than 5.0 cm in diameter) underwent dynamic MDCT and SPIO-enhanced MRI, as well as CTHA and CTAP. The images were reviewed by four independent and blinded readers on a tumor-by-tumor basis. RESULTS: The mean areas under alternative-free response receiver operating characteristic curve (Az) for combined dynamic MDCT and SPIO-enhanced MRI (IV set) and combinedCTHA and CTAP (IA set) were comparable (0.948 and 0.969, respectively, P > 0.05), although the Az value of the IV set was significantly lower than that of the IA set in HCCs smaller than or equal to 1.5 cm (0.867 and 0.937, respectively, P = 0.033). The mean sensitivity and positive predictive value of the IV set were similar to those of the IA set. CONCLUSIONS: Combined dynamic MDCT and SPIO-enhanced MRI showed a diagnostic accuracy comparable to intra-arterial contrast-enhanced CT (CTHA and CTAP) for hypervascular HCC, and may be a useful diagnostic option prior to curative treatments of hypervascular HCC, although a limitation exists in detecting HCCs smaller than or equal to 1.5 cm.

Discordance of motion artifacts on magnetic resonance imaging in Creutzfeldt-Jakob disease: comparison of diffusion-weighted and conventional imaging sequences.

PURPOSE: Motion artifact is problematic in the diagnosis of Creutzfeldt-Jakob disease (CJD) because of dementia. The purpose was to compare the occurrence of this artifact between a diffusion-weighted (DW) magnetic resonance (MR) imaging sequence and conventional sequences. MATERIALS AND METHODS: Ten MR examinations comprising T2-weighted, T1-weighted, DW, and fluid-attenuated inversion recovery imaging in seven CJD patients were retrospectively evaluated. The occurrence of motion artifacts on each sequence were assessed, and the examination was classified into four groups as follows: group A, motion artifact not revealed on DW imaging but revealed on one or more other sequences; group B, revealed on DW imaging and one or more other sequences; group C, not revealed on any sequences; and group D, revealed on DW imaging but not on any other sequences. RESULTS: The 10 MR examinations were classified as eight group A (80%), one B (10%), one C (10%), and zero D (0%). CONCLUSION: Motion artifacts are likely to occur in any conventional imaging sequences in CJD, but the fast-imaging ability of DW imaging can reduce this artifact. The combination of an absence of motion artifact on DW imaging and the presence on conventional sequences may be one of the frequent findings of CJD.

"Prominent ear sign" on diffusion-weighted magnetic resonance imaging in relapsing polychondritis.

Relapsing polychondritis is a rare autoimmune disease characterized by recurrent inflammation of cartilage in multiple sites of the body, including the auricles. Central nervous system involvement appears rare. We encountered a case of relapsing polychondritis with encephalitis that could be diagnosed by the unique appearance of the auricle with signal hyperintensity on diffusion-weighted magnetic resonance imaging.

Whole-body MRI for detecting metastatic bone tumor: diagnostic value of diffusion-weighted images.

PURPOSE: We assessed the diagnostic value of whole body magnetic resonance (MR) imaging (WB-MRI) using diffusion-weighted images (DWI) for detecting bone metastasis and compared it with that of skeletal scintigraphy (SS). MATERIALS AND METHODS: Thirty patients with malignancies (breast cancer, 17 patients; prostate cancer, 9; and one patient each, thyroid cancer, liposarcoma, leiomyosarcoma, and extraskeletal Ewing sarcoma) underwent both WB-MRI and SS to detect bone metastasis. All patients were followed more than 6 months by MR imaging, SS, or computed tomographic (CT) examination. For WB-MRI, patients were placed in feet-first supine position with table-top extender and quadrature body coil. We acquired DWI (axial plane from lower neck to proximal femur) (single shot short TI inversion-recovery [STIR]: repetition time [TR] 6243/echo time [TE] 59/inversion time [TI] 180 ms; b value: 600 s/mm(2); 5-mm slice thickness; 112 x 112 matrix), T(1)-weighted fast spin echo (T(1)WI), and STIR (sagittal plane of total spine images and coronal plane of whole body images) images. Four blinded readers independently and separately interpreted images of combined MR sequences of T(1)WI+STIR (session 1) and T(1)WI+STIR+DWI (session 2). RESULTS: In 10 of 30 patients, we detected a total of 52 metastatic bone lesions; in the other 20, follow-up examinations confirmed no metastatic bone lesions. For these 52 lesions, for session 2, the mean sensitivity was 96% and the positive predictive value (PPV) was 98%. Those values were superior to those of session 1 (sensitivity: 88%; PPV: 95%) and those of SS (sensitivity: 96%; PPV: 94%). CONCLUSION: WB-MRI that included DWI was useful for detecting bone metastasis.

Noninvasive method using multidetector CT for calculating the relative blood supply ratio of duplicated renal arteries in renal donors.

PURPOSE: The aim of this study was to evaluate the correlation between the renal artery cross-sectional area measured by multidetector computed tomography (MDCT) and the nephrogram area calculated by renal arteriography in potential living renal donors with duplicated renal arteries. MATERIALS AND METHODS: Medical records of 18 patients with duplicated renal arteries who underwent both MDCT angiography and renal arteriography between 2001 and 2003 were retrospectively reviewed. All 20 kidneys were evaluated. Renal artery cross-sectional areas were measured using the workstation to which the CT data were transferred; the nephrogram areas on the digitized angiographic images were calculated using public domain software. Bland-Altman analysis was performed to compare the cross-sectional area ratio of the accessory arteries to the main renal arteries, with the ratios obtained from the nephrogram areas calculated from the arteriograms. RESULTS: The mean cross-sectional areas of the accessory and main renal arteries were 6.78 and 20.9 mm2, respectively. The ratio of the nephrogram areas calculated from the arteriograms ranged from 0.094 to 0.809. Bland-Altman analysis showed no significant difference. CONCLUSION: It is possible to predict the supply volume of accessory renal arteries by measuring the cross-sectional area of the accessory and main renal arteries in potential living renal donors.

Principles and techniques of transcatheter embolotherapy for peripheral vascular lesions.

Transcatheter embolotherapy (TCE), a common procedure for interventional radiologists, comprises transcatheter delivery of embolic agents into target vessels in order to eliminate lesions or lesion-associated symptoms. Good knowledge of delivery catheters and embolic agents is essential to optimize embolization techniques and to obtain the desired therapeutic outcomes. In this review, we describe the principles and techniques of TCE for peripheral arterial and venous lesions featuring visceral aneurysms, peripheral and pulmonary arteriovenous malformations (AVMs), and varicoceles.

T-staging of gastric cancer of air-filling multidetector-row CT: comparison with hydro-multidetector-row CT.

PURPOSE: The purpose of this study was to evaluate the accuracy of T-staging of gastric cancer by air-filling multidetector-row CT (air-MDCT) compared with water-filling MDCT (hydro-MDCT). MATERIALS AND METHODS: One hundred fifteen patients with histologically diagnosed gastric cancer were included in this study. Fifty-eight patients underwent air-MDCT, and the remaining 57 had hydro-MDCT using a 64-channel scanner. Based on the volumetric data of contrast-enhanced MDCT obtained about 75 s after intravenously injecting 525 mg iodine per kilogram patients weight (525 mgI/kg) nonionic contrast material at the rate of 2 ml/s, oblique coronal and oblique sagittal multi-planar reformatted images perpendicular to the stomach wall, including the tumor, were reconstructed on a workstation. Mural invasion of gastric cancer into the gastric wall, as visualized by CT, was classified according to the TNM classification, and the results of T-staging by MDCT were compared with those by pathologic analysis after surgery. RESULTS: Correct assessment of T-staging by air-CT was achieved in 48 of 58 patients (83%), and that by hydro-MDCT was 49 of 57 patients (86%). The sensitivity, specificity, and accuracy of the technique in determining the invasion of serosa were 88%, 93%, and 91% for air-CT and 83%, 95%, and 91% for hydro-CT. There were no significant differences between hydro-MDCT and air-MDCT in sensitivity (P=0.73), specificity (P=0.71) and accuracy (P=0.98). CONCLUSION: Air-MDCT is a very valuable tool in T-staging of gastric cancer as well as hydro-MDCT.

Fourth ventricular mixed germ cell tumor demonstrating adipose tissue in a young adult.

We report a case of fourth ventricular mixed germ cell tumor (GCT) in a 20-year-old man. Neuroradiological investigations revealed a fourth ventricular hemorrhagic tumor with adipose tissue. We suspected mixed GCT because adipose tissue was seen preoperatively, but mixed GCT occurring after childhood in this location has not previously been reported. We describe herein the imaging findings for mixed GCT and discuss the differential diagnoses of fourth ventricular tumors with adipose tissue.

Assessment of two 3D MDCT colonography protocols for observation of colorectal polyps.

OBJECTIVE: The objective of our study was to assess the value of two-way interpretation (i.e., from rectum to cecum and vice versa) compared with one-way interpretation (i.e., from rectum to cecum only) in terms of polyp detection and interpretation time on MDCT colonography. MATERIALS AND METHODS: Fifty consecutive patients underwent both CT colonography and conventional colonoscopy. Three radiologists independently analyzed the CT colonographic examinations of each patient using a primary 3D method. All examinations were analyzed using two techniques: navigation from rectum to cecum only (one-way) and navigation from rectum to cecum and vice versa (two-way). Sensitivity and positive predictive value were calculated on both a per-polyp basis and a per-patient basis. Alternative free-response receiver operating characteristic (ROC) curve analysis was estimated, and image interpretation time was documented. RESULTS: One hundred fifty-five polyps were depicted in 45 patients by colonoscopy. The mean sensitivity of CT colonography for polyp detection with two-way (88.4%) was significantly superior to that with one-way (78.1%) (p < 0.01). The mean positive predictive value of each observer with one-way was 66.7%, whereas that with two-way was 65.8%. The mean area under the alternative free-response ROC curve (A(z) value) with two-way (0.827) was higher than that with one-way (0.816), but there was not a statistically significant difference. The average interpretation time of each observer with two-way (39 min) was statistically significantly longer than that with one-way (25 min) (p < 0.01). CONCLUSION: When using a primary 3D interpretation technique at CT colonography, complete 3D navigation from rectum to cecum and from cecum to rectum is mandatory to maximize polyp detection. The image interpretation time for two-way interpretation is statistically significantly longer than that with one-way interpretation.

Hepatic metastases: detection with multi-detector row CT, SPIO-enhanced MR imaging, and both techniques combined.

PURPOSE: To retrospectively compare the accuracy in detection of hepatic metastases among contrast material-enhanced multi-detector row computed tomography (CT) alone, superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging alone, and a combination of contrast-enhanced CT and SPIO-enhanced MR imaging. MATERIALS AND METHODS: The ethics committee did not require its approval or informed consent for this retrospective study, which was compliant with Declaration of Helsinki principles. Data in 38 patients (22 men, 16 women; mean age, 64.5 years; range, 35-78 years) suspected of having hepatic metastases who underwent both contrast-enhanced CT and SPIO-enhanced MR imaging were retrospectively analyzed. Twenty-one of the 38 patients had 61 metastases. Seventeen of the 61 metastases were confirmed histologically; the remaining 44 metastases were defined with imaging follow-up. At MR imaging, SPIO-enhanced heavily T1-weighted images, T2*-weighted gradient echo images, and T2-weighted fast spin-echo images were evaluated. Contrast-enhanced multi-detector row CT images obtained in the portal phase were evaluated. Four blinded observers independently reviewed CT images, MR images, and the combination of CT and MR images. Diagnostic accuracy was evaluated by using the alternative free-response receiver operating characteristic (AFROC) method. Sensitivities and positive predictive values were also analyzed with the Fisher protected least significant difference test and generalized estimating equations. RESULTS: The mean area under the AFROC curve for the combined approach (0.70) was significantly higher than that for SPIO-enhanced MR imaging alone (0.58, P < .05, Fisher protected least significant difference test), and there was no significant difference between each of them and that for contrast-enhanced CT alone (0.66). For all lesions, the mean sensitivity of combined imaging (0.59) was significantly higher than that of CT (0.48) or MR imaging (0.43) alone (P < .05, Fisher protected least significant difference test and generalized estimating equations). For all lesions, the mean positive predictive values were 0.82, 0.89, and 0.81, for combined MR and CT, CT alone, and MR alone, respectively. CONCLUSION: The addition of SPIO-enhanced MR imaging to contrast-enhanced multi-detector row CT (ie, combined analysis of SPIO-enhanced MR images and contrast-enhanced CT images) can improve sensitivity in the detection of hepatic metastases, although this improvement in sensitivity was not significant at AFROC analysis.