Tomohide Yoneyama

Distinguishing Adrenal Adenomas from Nonadenomas: Combined Use of Diagnostic Parameters of Unenhanced and Short 5-minute Dynamic Enhanced CT Protocol

PURPOSE To retrospectively examine the diagnostic values of individual parameters obtained from unenhanced and 35-second and 5-minute contrast material-enhanced (enhanced) computed tomography (CT) in distinguishing adenomas, particularly lipid-poor adenomas, from nonadenomas and to determine the best diagnostic method by using these parameters. MATERIALS AND METHODS This retrospective study had institutional review board approval; the need for informed consent was waived. The study population consisted of 61 patients (20 men and 41 women; mean age, 58 years) with 68 adrenal masses (53 adenomas and 15 nonadenomas). In each patient, unenhanced CT was followed by 35-second and 5-minute enhanced CT. Adenomas were classified as 30 lipid-rich (<or=10 HU) and 23 lipid-poor (>10 HU) adenomas by using unenhanced attenuation. The diagnostic parameters were tumor size, unenhanced attenuation, 35-second and 5-minute enhanced attenuation, wash-in and washout attenuation, percentage enhancement washout ratio (PEW), and relative PEW (RPEW). The sensitivity, specificity, and accuracy for diagnosing adenomas were calculated by using a threshold level of each parameter determined by the least sum of false-positive and false-negative cases and a combination of the threshold levels with 100% specificity. RESULTS The best results were obtained by using a combination of the threshold levels with 100% (15 of 15) specificity (presence of at least one of the following criteria for diagnosing adenomas: unenhanced attenuation of <or=19 HU, 5-minute attenuation of <or=50 HU, PEW of >or=45%, and RPEW of >or=31%). Sensitivity was 94% (50 of 53) or 87% (20 of 23) and accuracy was 96% (65 of 68) or 92% (35 of 38) for diagnosing total adrenal adenomas or lipid-poor adenomas, respectively. CONCLUSION Combining the diagnostic parameters of the CT protocol can yield diagnostic results comparable to those with previously reported longer dynamic enhanced CT protocols.

Quantitative evaluation of liver function with T1 relaxation time index on Gd-EOB-DTPA-enhanced MRI: Comparison with signal intensity-based indices

To evaluate whether the reduction rate of T1 relaxation time of the liver (T1 relaxation time index) before and 20 minutes after gadolinium‐ethoxybenzyl‐diethylenetriaminepentaacetic acid (Gd‐EOB‐DTPA) injection has the potential to serve as an magnetic resonance imaging (MRI)‐based liver function test in comparison with signal intensity‐based indices.

Muscle Mass and Composition of the Hip, Thigh and Abdominal Muscles in Women With and Without Hip Osteoarthritis

The objective of this study was to compare muscle mass and composition between individuals with and without hip osteoarthritis. Twenty-four women with hip osteoarthritis (OA group) and 16 healthy women (healthy group) participated in this study. Muscle thickness (MT) and echo intensity (EI) were measured as indices of muscle mass and composition, respectively, using ultrasound imaging. Seven muscles were examined: gluteus maximus, gluteus medius, quadriceps femoris, rectus abdominis, external oblique, internal oblique and transversus abdominis. MT of only quadriceps femoris in the OA group was significantly thinner than that in the healthy group. EIs of gluteus medius, quadriceps femoris and rectus abdominis were significantly higher in the OA group than those in the healthy group. Thus, actual contractile tissue of gluteus medius and rectus abdominis substantially decreased, although muscle mass was similar, whereas both quantitative and qualitative changes occurred in quadriceps femoris in patients with hip OA.

Contrast-enhanced CT and diffusion-weighted MR imaging: Performance as a prognostic factor in patients with pancreatic ductal adenocarcinoma

OBJECTIVE To determine whether contrast enhancement of CT and apparent diffusion coefficient on diffusion-weighted MR imaging are important parameters that can predict outcomes for patients with pancreatic ductal adenocarcinoma. MATERIALS AND METHODS Ninety-two patients with histologically confirmed pancreatic ductal adenocarcinoma who underwent quadriphasic CT (including unenhanced, pancreatic parenchymal, portal venous and delayed phases) and fat-suppressed single-shot echo-planar diffusion-weighted MR imaging at 3.0 T were retrospectively analyzed to investigate prognostic factors. Overall survival curves were drawn using the Kaplan-Meier method. Effects on survival of variables including age, sex, tumor location, tumor size, TNM stage, carbohydrate antigen 19-9, carcinoembryonic antigen, treatment, tumor contrast enhancement and apparent diffusion coefficient values were analyzed in univariate analysis using the log-rank test. Variables were analyzed in multivariate analyses using the Cox proportional hazards regression model. RESULTS Median survival for the entire patient population was 18.2 months. Higher contrast enhancement during all phases was associated with significantly longer overall survival (P<0.001 for all phases). The difference in overall survival between groups divided by median apparent diffusion coefficient value was not significant (P=0.672). TNM stage (P=0.026) and tumor contrast enhancement on CT (P=0.027) were significantly related to survival in multivariate analysis. CONCLUSIONS Poor enhancement of pancreatic adenocarcinomas on enhanced CT is associated with reduced patient survival.

Left renal vein aneurysm: imaging findings

AbstractA renal vein aneurysm is a rare vascular disease. To our knowledge, only six cases have been reported. We describe a 57-year-old woman with a left renal vein aneurysm diagnosed by a combination of ultrasonography, color Doppler ultrasonography, contrast-enhanced computed tomography, and magnetic resonance imaging.

Computed tomography and magnetic resonance imaging features of lipid-rich neuroendocrine tumors of the pancreas.

AIM To clarify the computed tomography (CT) and magnetic resonance imaging (MRI) characteristics of lipid-rich pancreatic neuroendocrine tumors (PanNETs). METHODS Enhanced CT and MRI performed before pancreatectomy in 29 patients with 34 histologically-confirmed PanNETs was retrospectively reviewed. Tumor attenuation on CT and signal intensities on conventional (T1- and T2-weighted) and chemical shift MRI were qualitatively analyzed and compared alongside adipose differentiation-related protein (ADRP) immunostaining (ADRP-positive: lipid-rich; ADRP-negative: non-lipid-rich) results using Fishers exact test or the Mann-Whitney U test. Signal intensity index on chemical shift MRI was quantitatively assessed. RESULTS There were 15 lipid-rich PanNETs (44.1%) in 12 patients (41.4%). Tumor attenuation during the early, portal venous, and delayed phases of enhanced CT (P = 0.888, 0.443, and 0.359, respectively) and signal intensities on conventional MRI (P = 0.698 and 0.798, respectively) were not significantly different between lipid-rich and non-lipid-rich PanNETs. Four of the 15 lipid-rich PanNETs exhibited high signal intensity on subtraction chemical shift MRI, and the association of high signal intensity on subtraction imaging with lipid-rich PanNETs was significant (4 of 15 lipid-rich PanNETs, 26.73%, vs 0 of 19 non-lipid-rich PanNETs, 0%, P = 0.029). Lipid-rich PanNETs showed a significantly higher signal intensity index than non-lipid-rich PanNETs (0.6% ± 14.1% vs -10.4% ± 14.4%, P = 0.004). Eight of 15 lipid-rich PanNETs, vs 0 of 19 non-lipid-rich PanNETs, had positive signal intensity index values in concordance with lipid contents. CONCLUSION CT contrast enhancement and conventional MR signal intensities are similar in lipid-rich and non-lipid-rich PanNETs. Chemical shift MRI can demonstrate cytoplasmic lipids in PanNETs.

Amide Proton Transfer Imaging of Cavernous Malformation in the Cavernous Sinus

Amide proton transfer (APT) imaging is an emerging molecular MRI technique based on chemical exchange saturation transfer where the imaging contrast is generated by endogenous mobile proteins and peptides. Previous studies have shown that APT signal increases with increasing malignancy grade of gliomas, hypothetically reflecting abundant cytosolic protein due to high cellularity. Cavernous malformation is rare, highly vascular benign lesion that has very low cellularity. Here, we report a cavernous malformation that showed markedly high APT signal. A 70-year-old woman presented with left facial discomfort and progressive loss of vision in the left eye for 6 months. Magnetic resonance imaging was performed using a 3T scanner (Ingenia 3.0T; Philips Healthcare, Best, The Netherlands) equipped with dual-source parallel radiofrequency transmission system and a 15-channel head coil for signal reception, which revealed a left cavernous sinus mass with hypointensity on T1-weighted imaging, marked hyperintensity on T2-weighted imaging, and strong homogenous enhancement after contrast injection (Fig. 1). Amide proton transfer imaging based on two-dimensional single slice single-shot turbo spin-echo technique was performed: TR, 4550 ms; TE, 4.8 ms; flip angle 90°; turbo factor 128; number of signal averaging, 1; FOV, 230 × 230 mm2; imaging matrix, 128 × 128 (reconstructed in 256 × 256); slice thickness, 5 mm. A quasi-continuous saturation pulse with an amplitude of 2 μT and a duration of 2 s (40 × 50 ms, sin c-Gaussian elements) was applied at 27 offset frequencies including 24 ranging from +6 to −6 ppm with a step of 0.5 ppm and 2 at ±9.6 ppm as well as one far off-resonance frequency (−1560 ppm) for signal normalization. During postprocessing, the B0 field inhomogeneity was corrected on a voxel-by-voxel basis using a separately obtained map of B0. The APT images were obtained by calculating the magnetization transfer ratio asymmetry (MTRasym) between ±3.5 ppm using the B0-corrected MT-spectrum:

Whole-tumor apparent diffusion coefficient (ADC) histogram analysis to differentiate benign peripheral neurogenic tumors from soft tissue sarcomas: Differentiation of BPNSTs From STSs

Apparent diffusion coefficient (ADC) histogram analyses have been used to differentiate tumor grades and predict therapeutic responses in various anatomic sites with moderate success.

Pancreatic adenocarcinoma: analysis of the effect of various concentrations of contrast material.

PurposeThe aim of this study was to compare the efficacy of two contrast materials with moderate and high iodine concentrations for the depiction of pancreatic adenocarcinoma.Materials and methodsA series of 107 patients with histologically proven pancreatic adenocarcinoma underwent helical computed tomography. A fixed dose of 100 ml of iopamidol 300 (mg I/ml) was administered to 50 patients (group A) and iopamidol 370 (mg I/ml) to 57 patients (group B) at the same injection rate (3 ml/s). Unenhanced helical scans and contrast-enhanced scans for three phases (30, 70, and 300 s after starting the infusion of contrast material) were obtained. We evaluated enhancement of the aorta, portal vein, hepatic parenchyma, pancreatic parenchyma, and pancreatic adenocarcinoma during each phase.ResultsDuring all phases, both aortic and pancreatic enhancement were significantly greater in group B than in group A (P < 0.01). Enhancement of the portal vein and hepatic parenchyma was significantly greater at 70 and 300 s in group B than in group A (both P < 0.01). Tumor-to-pancreas contrast was significantly greater in group B than in group A at both 30 s (P < 0.01) and 70 s (P < 0.05).ConclusionAdministration of contrast material with a high iodine concentration is more effective for depicting pancreatic adenocarcinomas.

Amide proton transfer imaging of tumors: theory, clinical applications, pitfalls, and future directions

Amide proton transfer (APT) imaging is an emerging molecular magnetic resonance imaging technique based on chemical exchange saturation transfer (CEST). APT imaging has shown promise in oncologic imaging, especially in the imaging of brain tumors. This review article illustrates the theory of CEST/APT imaging and describes the clinical utility, pitfalls, and potential for future development of APT imaging.