CT and MR features of struma ovarii

Objective

The purpose of this study is to investigate radiologic findings of struma ovarii, and to correlate both CT and MR findings.

Materials and methods

MR images of 26 cases were retrospectively reviewed. Post-contrast enhanced T1-weighted images were available in 17 patients. CT images, including seven non-contrast and eleven post-contrast studies, were available for review in 13 cases.

Results

All 26 tumors appeared as well-defined cystic tumors with solid components, which were multilobulated surfaces in 19 and smooth surfaces in seven. Twenty-four was multicystic, whereas two were unilocular. The solid components were recognized as thickened septi or walls in 23 and a mass in three tumors. On T2-weighted images, loculi of prominent low intensity were recognized in 16 tumors. On T1-weighted images, the punctuate foci of high intensity were recognized in 24 tumors in or adjacent to the solid components. Ascites was present in only one lesion. In six of seven cases with non-contrast CT images, high attenuation areas were recognized. In five of these six tumors, high attenuation areas corresponded to the areas of prominent low intensity and the solid components on T2-weighted images. In seven cases with CT, curvilinear calcifications were recognized in the solid components.

Conclusion

Struma ovarii typically presents as a lobulated multicystic lesion with solid components. The tumors frequently include loculi of low intensity on T2-weighted images and punctuate foci of high intensity on T1-weighted images. On CT, high attenuation areas and calcifications in the solid components are common findings.     

Retroperitoneal schwannomas in the anterior pararenal space: dynamic enhanced multi-slice CT and MR findings

Background

To evaluate the imaging features of schwannomas in the anterior pararenal space (APS), especially focusing on dynamic enhanced multi-slice CT (MSCT) and MR findings.

Patients and methods

Eight patients with pathologically proved retroperitoneal schwannomas in the APS underwent dynamic enhanced multi-slice CT (MSCT), while three of these patients also had a contrast-enhanced MR examination. The imaging findings were retrospectively reviewed.

Results

All eight cases exhibited forward displacement of the pancreas, and three cases showed lateral displacement and compression of the inferior vena cava. The tumors had round or oval shape with a maximal axial diameter of 4.0–12.3 cm (average, 6.7 cm). All eight tumors were solitary and well circumscribed. Of the eight retroperitoneal schwannomas in the APS, six exhibited a capsule with thickness of 1.0–2.0 mm, one showed punctate calcification, two displayed cystic degeneration, and three revealed a “target sign” on CT and MR. The tumors were hypo-dense on unenhanced CT images, hyper-intense on T2W images, and homogeneously hypo-intense on T1W images. All eight tumors exhibited gradual enhancement on dynamic enhanced CT or MR images. One case showed delayed enhancement. Heterogeneous enhancement was the dominant pattern occurring in seven out of eight tumors.

Conclusion

The imaging findings of schwannoma in the APS correspond with its pathological composition. Schwannoma should be included in the differential diagnosis of tumors in the APS.     

Rectal cancer in inflammatory bowel diseases: MR imaging findings

Purpose

To retrospectively analyze the MR imaging features of rectal cancer in patients with inflammatory bowel diseases (IBD).

Materials and methods

The MR imaging examinations of 13 patients with IBD-related rectal cancer were retrospectively reviewed. MR imaging included T2-weighted, diffusion-weighted (DW), and gadolinium chelate-enhanced MR imaging. MR imaging findings were analyzed and compared with endoscopic and histopathological findings.

Results

Eight patients (8/13; 62%) had active IBD and five (5/13; 38%) had quiescent IBD on MR imaging. Two different tumor patterns were individualized including clearly visible soft-tissue mass (4/13; 31%) (Type 1 tumor) and marked circumferential rectal wall thickening (9/13; 69%) (Type 2 tumor). Twelve tumors (12/13; 92%) showed high signal intensity on T2-weighted MR images. All six tumors studied with DW-MR imaging (6/6; 100%) showed high signal on DW-MR imaging with restricted diffusion on apparent diffusion coefficient (ADC) map. On gadolinium chelate-enhanced MR imaging, heterogeneous enhancement was observed in one tumor (1/13; 8%), whereas 12 tumors (12/13; 92%) showed homogeneous enhancement. MR imaging showed pelvic fistula and intrapelvic abscess in association with four (4/13; 31%) and two tumors (2/13; 15%), respectively.

Conclusion

Our limited retrospective study demonstrates that rectal cancer in IBD patients can present as a circumferential wall thickening resembling inflammation and can occur in the absence of fistula or abscess. The use of T2-weighted and DW-MR imaging is recommended to improve rectal cancer detection in patients with long-standing IBD.     

Early phase detection of bile leak after hepatobiliary surgery: value of Gd-EOB-DTPA-enhanced MR cholangiography

Purpose

To assess the value of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR cholangiography for the detection of bile leaks after hepatobiliary surgery.

Methods

Twenty-three patients with symptoms suggestive of bile leak underwent conventional fat-suppressed T1- and T2-weighted MR cholangiography followed by Gd-EOB-DTPA-enhanced MR cholangiography using gradient-echo (GRE) T2-weighted sequences and fat-suppressed T1-weighted 3D gradient-echo sequences 20?min after an intravenous bolus of Gd-EOB-DTPA. The results of Gd-EOB-DTPA-enhanced MR cholangiography correlated with clinical findings, surgical repair, and the results of endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography.

Results

The results of Gd-EOB-DTPA-enhanced MR cholangiography were negative in 13 patients (cholecystectomy 5, liver transplantation 2, liver resection for focal lesions 2, cholangiocarcinoma 1, and partial hepatectomy after liver injury 1). In 10 patients in whom bile leaks were detected, this complication occurred after liver resection for focal lesions in 3, cholecystectomy in 4, liver transplantation in 2, and liver resection for intrahepatic cholangiocarcinoma in 1. The diagnostic accuracy of Gd-EOB-DTPA-enhanced MR for the detection or exclusion of bile leaks was 100%.

Conclusions

Gd-EOB-DTPA-enhanced MR cholangiography is a highly reliable technique for the detection of bile leaks after hepatobiliary surgery and may avoid the use of other, potentially risky invasive diagnostic techniques.     

Ovarian mucinous cystadenoma coexisting with benign Brenner tumor: MR imaging findings

Purpose

The purpose of this study was to describe the MR imaging findings of ovarian mucinous cystadenomas coexisting with benign Brenner tumors.

Materials and methods

MR images with a 1.5-T unit obtained in five consecutive patients (age range, 51–72 years; mean age, 61 years) with surgically confirmed ovarian mucinous cystadenomas coexisting with benign Brenner tumors were retrospectively reviewed for the presence, configuration, and signal intensity of cystic and solid components of the lesions.

Results

Tumors ranged in size from 7.5 to 22.1 cm (mean, 13.5 cm). In four patients (80%), the size of mucinous cystadenoma (range 6.4–22.1 cm; mean, 12.5 cm) was larger than that of Brenner tumor (range 0.2–9.1 cm; mean, 2.8 cm). All patients (100%) had cystic, and three (60%) had solid components. Four patients (80%) showed multilocular cystic, and one (20%) showed unilocular cystic appearance. MR imaging findings were classified into three patterns: (1) a bulky solid mass adjacent to the cystic component, (2) a mural nodule at the periphery of the cystic component, and (3) a cystic component without a detectable solid component. All four multilocular cystic areas exhibited “stained glass” appearances on both T1- and T2-weighted images, and all three solid areas showed homogeneous hypointensity on T2-weighted images.

Conclusion

Mucinous cystadenomas were often larger than the coexisting benign Brenner tumors. Mucinous cystadenomas coexisting with benign Brenner tumors should be considered when multilocular or unilocular cystic components are accompanied by homogeneously hypointense solid components on T2-weighted images.     

Pelvic inflammatory disease: evaluation of diagnostic accuracy with conventional MR with added diffusion-weighted imaging

Purpose

To determine the incremental value of magnetic resonance (MR) diffusion-weighted (DW) imaging for the diagnosis of pelvic inflammatory diseases (PID).

Materials and methods

We added DW sequences to conventional MR imaging in 187 patients with clinically suspected PID. The imaging findings included shape, signal intensity on T1-weighted, T2-weighted, and DW imaging, shade in the peripheral lesions, free pelvic fluid, and lymphadenopathy.

Results

Laparoscopic and pathological findings confirmed the diagnosis in all patients. Conventional MR findings were consistent with a diagnosis of PID in 90.7% (117/129) and of non-PID in 93.3% (28/30) of the 159 patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of conventional MR imaging findings vs. the addition of DW imaging to conventional MR protocols for predicting PID were 90.7%, 93.3%, 98.3%, 70.0%, and 91.2% and 98.4%, 93.3%, 98.4%, 93.3%, and 97.5%, respectively.

Conclusion

The addition of DW sequences to conventional MR imaging can improve the accuracy of diagnosis in PID.     

Primary hepatic neuroendocrine carcinoma: MR imaging findings including preliminary observation on diffusion-weighted imaging

Purpose

To investigate MR imaging findings of primary hepatic neuroendocrine carcinoma (PHNEC) including preliminary observations on diffusion-weighted imaging (DWI).

Materials and methods

MR images of eight patients with pathologically confirmed PHNEC were retrospectively analyzed. The morphological characteristics and dynamic enhancement patterns were evaluated.

Results

One case showed a well-defined solitary nodule with homogenous hypointensity on T1-weighted imaging (T1WI) and hyperintensity on T2-weighted imaging (T2WI) and DWI. The remaining seven cases appeared as well-defined dominant masses with multiple satellite nodules. The dominant masses demonstrated heterogeneous hypointensity on T1WI and hyperintensity on T2WI, which all appeared as a marked enhancement at arterial phase and rapid washout at portal venous phase. Six cases demonstrated rim-like enhancement at equilibrium phase. The satellite lesions showed heterogeneous hypointensity on T1WI and marked hyperintensity on T2WI with variable enhancements, such as homogeneous, rim-like enhancement. All the dominant masses and satellite nodules appeared as markedly hyperintensity and reduced apparent coefficient (ADCs) values on DWI. The mean ADC value of the tumors was significantly lower than that of surrounding liver parenchyma (1.02 ± 0.57 vs. 2.24 × 10^?3 mm²/s, p = 0.000).

Conclusion

PHNECs typically appear as a large dominant hypervascular mass accompanied by satellite nodules, with rapid washout and capsular enhancement on dynamic MR imaging and restricted diffusion on DWI.     

Deep infiltrating endometriosis of the bowel: MR imaging as a method to predict muscular invasion

Purpose

To evaluate magnetic resonance (MR) imaging morphologic- and signal intensity abnormalities of deep infiltrating endometriosis (DIE) of the bowel wall and to assess its value in predicting depth and extent of bowel wall infiltration.

Materials and methods

This single-center study was performed in a tertiary referral center for endometriosis. All patients (n?=?28) who underwent segmental bowel resection (2004–2010) were retrospectively studied. MR images were analyzed by two experienced readers independently (number of lesions, location, size, signal intensity, and depth of bowel wall infiltration) and this was correlated with histopathology.

Results

The sensitivity, specificity, positive and negative predictive values, and accuracy for diagnosis of endometriosis infiltrating the muscular layer of the bowel were 100%, 75%, 96%, 100%, and 96%, respectively. The inter-rater agreement was 0.84. “Fan shaped” configurations with hypointensity on T2- and T1-weighted imaging were characteristic for thickening of indigenous smooth muscle and smooth muscle hyperplasia at histopathology, as a consequence of infiltration by endometriosis. Thickening of the (sub)mucosa corresponded to edema with or without infiltration of endometriosis.

Conclusion

MR imaging at 1.5 Tesla is useful to predict muscular infiltration of the bowel in endometriosis, whereas it is of limited value in diagnosis of (sub)mucosal infiltration.     

Effect of steatosis on liver signal and enhancement on multiphasic contrast-enhanced magnetic resonance imaging

Purpose

To investigate the effect of steatosis on liver signal and enhancement in multiphasic contrast-enhanced (MCE) MRI.

Materials and methods

In this IRB-approved, HIPAA-compliant, retrospective, observational study, 1217 MCE abdominal MRIs performed during 2014 at a single institution were reviewed. Of these, 1085 were excluded, due to potential factors other than steatosis that may affect liver signal intensity and/or enhancement. In the remaining 132, liver fat fraction (FF) was calculated from the in- and opposed-phase 2D T1-weighted images. Liver signal intensity, absolute enhancement, and relative enhancement on fat-suppressed (Dixon method) 3D T1-weighted images before and after injection of gadobutrol (arterial, portal venous, and equilibrium phases) were plotted against co-localized FF values and the linear trend was evaluated by Pearson correlation coefficient (r). P values <0.05 were considered statistically significant.

Results

Liver signal intensity negatively correlated with FF for all phases (r = ?0.388 to ?0.544, p < 0.001). Absolute enhancement negatively correlated with FF for the portal venous and equilibrium phases (r = ?0.286 and ?0.289, respectively, p < 0.001), but not for the arterial phase (r = ?0.042, p = 0.632). Relative enhancement did not significantly correlate with FF for any phase (p ≥ 0.125).

Conclusion

Steatosis reduces liver signal intensity in MCE MRI. This effect of steatosis was reduced in calculated absolute enhancement and eliminated in calculated relative enhancement.

     

Hepatic pseudolymphoma: imaging–pathologic correlation with special reference to hemodynamic analysis

Objectives

To clarify radiological findings and hemodynamic characteristics of hepatic pseudolymphoma, as compared with the histopathological findings.

Methods

Radiological findings of ten histopathologically confirmed hepatic pseudolymphomas in seven patients were examined using US, CT, and MRI. Six patients also underwent angiography-assisted CT, including CT during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) to analyze hemodynamics.

Results

The nodules were depicted as hypoechoic on US, hypodense on precontrast CT, hypointense on T1-weighted images, and hyperintense on T2-weighted images. On contrast-enhanced CT/MRI, they showed various degrees of enhancement, and sometimes, perinodular enhancement was observed at the arterial dominant and/or equilibrium phase. On CTAP, the nodules showed portal perfusion defects, including some in the perinodular liver parenchyma. On CTHA, irregular bordered enhancement was observed in perinodular liver parenchyma on early phase, and continued until delayed phase. Some nodules had preserved intra-tumoral portal tracts. Histopathologically, the nodules consisted of marked lymphoid cells. In perinodular liver parenchyma, stenosis or disappearance of portal venules, caused by lymphoid cell infiltration in the portal tracts, was observed.

Conclusions

Hepatic pseudolymphoma showed some characteristic radiological findings including hemodynamics on CT, MRI, and angiography-assisted CT. These findings are useful in the differentiation from hepatocellular carcinoma and other tumors.     

Detection of body packing by magnetic resonance imaging: a new diagnostic tool?

Purpose

In this study, we aimed to describe non-contrast abdominal MRI findings in body packers and emphasize the role of this imaging technique in diagnosis of body packing.

Materials and methods

Non-contrast abdominopelvic MRI was performed at the radiology department in 16 suspected body packers that were brought to our hospital, and 13 of them were diagnosed with body packing. We evaluated the presence, location, and shapes of packets as well as signal characteristics on T1- and T2-weighted images.

Results

We came across two types of packets: those containing solid substances (10 cases) and those filled with liquid cocaine (3 cases). Both types were accurately diagnosed with the help of MRI. Only 1 suspected body packer received a false positive diagnosis.

Conclusion

Abdominopelvic MRI is a reliable and valuable method of diagnosing body packing.     

Histogram Analysis of T1-Weighted,T2-Weighted,and Postcontrast T1-Weighted Images in Primary CNS Lymphoma: Correlations with Histopathological Findings—a Preliminary Study

Purpose

Previously, some reports mentioned that magnetic resonance imaging (MRI) can predict histopathological features in primary CNS lymphoma (PCNSL). The reported data analyzed diffusion-weighted imaging findings. The aim of this study was to investigate possible associations between histopathological findings, such as tumor cellularity, nucleic areas and proliferation index Ki-67, and signal intensity on T1-weighted and T2-weighted images in PCNSL.

Procedures

For this study, 18 patients with PCNSL were retrospectively investigated by histogram analysis on precontrast and postcontrast T1-weighted and fluid-attenuated inversion recovery (FLAIR) images. For every patient, histopathology parameters, nucleic count, total nucleic area, and average nucleic area, as well as Ki-67 index, were estimated.

Results

Correlation analysis identified several statistically significant associations. Skewness derived from precontrast T1-weighted images correlated with Ki-67 index (p = ? 0.55, P = 0.028). Furthermore, entropy derived from precontrast T1-weighted images correlated with average nucleic area (p = 0.53, P = 0.04). Several parameters from postcontrast T1-weighted images correlated with nucleic count: maximum signal intensity (p = 0.59, P = 0.017), P75 (p = 0.56, P = 0.02), and P90 (p = 0.52, P = 0.04) as well as SD (p = 0.58, P = 0.02). Maximum signal intensity derived from FLAIR sequence correlated with nucleic count (p = 0.50, P = 0.03).

Conclusion

Histogram-derived parameters of conventional MRI sequences can reflect different histopathological features in PSNCL.

     

Disc herniation diagnosis in MRI using a CAD framework and a two-level classifier

Purpose

Disc herniation in the lumbar spine is a common condition, so an automated method for diagnosis could be helpful in clinical applications. A computer-aided framework for disk herniation diagnosis was developed for use in magnetic resonance imaging (MRI).

Materials and Method

A computer-aided diagnosis framework for lumbar spine with a two-level classification scheme for disc herniation diagnosis was developed using heterogeneous classifiers: a perceptron classifier, a least mean square classifier, a support vector machine classifier, and a k-Means classifier. Each classifier makes a diagnosis based on a feature set generated from regions of interest that contain vertebrae, a disc, and the spinal cord. Then, an ensemble classifier makes a final decision using score values of each classifier. We used clinical MR image data from 70 subjects in T1-weighted sagittal view and T2-weighted sagittal view for evaluation of the system.

Results

MR images of 70 subjects were processed using the proposed framework resulting in successful detection of disc herniation with 99% accuracy, achieving a speedup factor of 30 in comparison with radiologist??s diagnosis.

Conclusion

The computer-aided framework works well to diagnose herniated discs in MRI scans. We expect the framework can be adapted to effectively diagnose a variety of abnormalities in the lumbar spine.     

Well-differentiated hepatocellular carcinoma: findings of US, CT, and MR imaging

Background: To elucidate the imaging characteristics of well-differentiated hepatocellular carcinomas (HCCs) on ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging. Methods: Ultrasonograms, CTs, and MR images of 18 histopathologically proven well-differentiated HCCs in 15 patients were reviewed. The findings of these images were correlated with histopathologic findings. Results: On US, seven tumors were depicted as a hyperechoic area and eight as a hypoechoic area. Three tumors were not visualized. On precontrast CT, four tumors were depicted as a low-density area, but 14 were not visualized. On conventional contrast-enhanced CT, 12 tumors were depicted as a low-density area but six were not visualized. On T1-weighted MR images, 10 tumors had high signal intensity and two had low signal intensity. Six tumors were not visualized. On T2-weighted MR images, five tumors had high signal intensity and two had low signal intensity. Eleven tumors were not visualized. Tumors with fatty change and/or clear cell formation were frequently hyperechoic on US and hyperintense on T1-weighted MR images. Conclusions: Well-differentiated HCCs show different findings on US, CT, and MR imaging. Therefore, reliable diagnosis of well-differentiated HCCs by these imaging techniques may be difficult. Received: 29 April 1998/Revision accepted: 15 July 1998     

MR comparative study of combined hepatocellular-cholangiocarcinoma in normal,fibrotic, and cirrhotic livers

Purpose

To compare MR imaging features of combined hepatocellular-cholangiocarcinoma (cHCC-CC) in normal, fibrotic, and cirrhotic livers.

Methods

A total of 64 patients with 67 pathologically proven cHCC-CCs were retrospectively analyzed. Patients were classified into three groups according to the patients’ liver condition: patients with normal liver (F0, group 1), fibrosis without cirrhosis (F1–3, group 2), and cirrhosis (F4, group 3). The morphological and MR signal features on T1- and T2-weighted, dynamic contrast-enhanced, diffusion-weighted imaging, as well as the accompanying imaging findings, were evaluated and compared.

Results

There were 12, 19, and 33 patients in groups 1, 2, and 3, respectively. Tumors in the fibrotic and cirrhotic livers were smaller than those in the normal liver, and tumors with cirrhosis had the smallest size (P = 0.0326). No statistical difference was found when comparing the signal intensity on T2-weighted imaging (P = 0.496), but iso- or hypointense lesions were only found in the fibrosis (n = 2) or cirrhosis group (n = 2). Enhancement pattern was different between groups, the washout pattern was more often seen in the cirrhosis group (P = 0.049), and the accompanying mosaic architecture was also more commonly seen in the cirrhosis group (P = 0.048). The ADC values of the lesions were not different among the three groups (P = 0.899).

Conclusion

MRI may provide valuable information for the diagnosis and differential diagnosis of cHCC-CC in normal, fibrotic, and cirrhotic livers. The nodule size, enhancement pattern, and the presence of mosaic architecture in cHCC-CC differ between different degrees of background liver disease.

     

Non-invasive Monitoring of Pancreatic Tumor Progression in the RIP1-Tag2 Mouse by Magnetic Resonance Imaging

Purpose

Assessing information on tumor progression in the RIP1-Tag2 mouse in vivo is a great challenge because the tumors form spontaneously throughout the pancreas and are difficult to detect with current imaging modalities. In this study, we focused on non-invasive magnetic resonance imaging, providing information on tumor growth.

Procedures

Tissue relaxation times were measured over time and were compared between tumors and healthy pancreatic tissue. The effects of age and body temperature on these relaxation times, possibly influencing image contrast and therefore detection capabilities, were evaluated.

Results

Tumors appeared hyperintense in T2-weighted images when they exceeded 0.8 mm in diameter, and both relaxation times showed significantly higher values in tumors than in the healthy pancreas.

Conclusion

Visualization and monitoring of these small tumors in vivo is feasible, even under adverse conditions of permanent gut movement. In the mouse model studied, the relaxation times of tumors differed significantly from healthy pancreatic tissue.     

Abnormal findings on multiparametric prostate magnetic resonance imaging predict subsequent biopsy upgrade in patients with low risk prostate cancer managed with active surveillance

Purpose

To determine the ability of multiparametric MR imaging to predict disease progression in patients with prostate cancer managed by active surveillance.

Methods

Sixty-four men with biopsy-proven prostate cancer managed by active surveillance were included in this HIPPA compliant, IRB approved study. We reviewed baseline MR imaging scans for the presence of a suspicious findings on T2-weighted imaging, MR spectroscopic imaging (MRSI), and diffusion-weighted MR imaging (DWI). The Gleason grades at subsequent biopsy were recorded. A Cox proportional hazard model was used to determine the predictive value of MR imaging for Gleason grades, and the model performance was described using Harrell’s C concordance statistic and 95% confidence intervals (CIs).

Results

The Cox model that incorporated T2-weighted MR imaging, DWI, and MRSI showed that only T2-weighted MR imaging and DWI are independent predictors of biopsy upgrade (T2; HR = 2.46; 95% CI 1.36–4.46; P = 0.003—diffusion; HR = 2.76; 95% CI 1.13–6.71; P = 0.03; c statistic = 67.7%; 95% CI 61.1–74.3). There was an increasing rate of Gleason score upgrade with a greater number of concordant findings on multiple MR sequences (HR = 2.49; 95% CI 1.72–3.62; P < 0.001).

Conclusions

Abnormal results on multiparametric prostate MRI confer an increased risk for Gleason score upgrade at subsequent biopsy in men with localized prostate cancer managed by active surveillance. These results may be of help in appropriately selecting candidates for active surveillance.     

Automated segmentation of basal ganglia and deep brain structures in MRI of Parkinson’s disease

Purpose

Template-based segmentation techniques have been developed to facilitate the accurate targeting of deep brain structures in patients with movement disorders. Three template-based brain MRI segmentation techniques were compared to determine the best strategy for segmenting the deep brain structures of patients with Parkinson’s disease.

Methods

T1-weighted and T2-weighted magnetic resonance (MR) image templates were created by averaging MR images of 57 patients with Parkinson’s disease. Twenty-four deep brain structures were manually segmented on the templates. To validate the template-based segmentation, 14 of the 24 deep brain structures from the templates were manually segmented on 10 MR scans of Parkinson’s patients as a gold standard. We compared the manual segmentations with three methods of automated segmentation: two registration-based approaches, automatic nonlinear image matching and anatomical labeling (ANIMAL) and symmetric image normalization (SyN), and one patch-label fusion technique. The automated labels were then compared with the manual labels using a Dice-kappa metric and center of gravity. A Friedman test was used to compare the Dice-kappa values and paired t tests for the center of gravity.

Results

The Friedman test showed a significant difference between the three methods for both thalami (p < 0.05) and not for the subthalamic nuclei. Registration with ANIMAL was better than with SyN for the left thalamus and was better than the patch-based method for the right thalamus.

Conclusion

Although template-based approaches are the most used techniques to segment basal ganglia by warping onto MR images, we found that the patch-based method provided similar results and was less time-consuming. Patch-based method may be preferable for the subthalamic nucleus segmentation in patients with Parkinson’s disease.     

Feasibility of blood oxygenation level-dependent MRI at 3T in the characterization of hepatic tumors

Purpose

To determine the feasibility of using blood oxygenation level-dependent (BOLD) MRI in the characterization of hepatic tumors.

Methods

A total of 100 patients with 43 hepatocellular carcinomas (HCCs), 36 metastases, 17 cholangiocarcinomas, and 23 hemangiomas underwent gadoxetic acid-enhanced and BOLD MRI at 3T. BOLD MRI was performed using a multiple fast-field echo sequence (TR/TE, 290/10–28; slice thickness 5 mm) to generate 20 T2*-weighted images. The T2* value of each tumor were calculated. On a color-coded T2* map, tumors were classified into five categories of high signal intensity (strong, moderate, rim, mild) and iso-intensity, which was correlated with the enhancement pattern on dynamic phases by two observers.

Results

The mean T2* value (ms) of hemangiomas (97.3 ± 20.2) was the highest, followed by HCCs (48.4 ± 12.7), metastases (37.1 ± 10.5), and cholangiocarcinomas (36.6 ± 11.1). These values were significantly different (hemangioma vs. others tumors and HCC vs. metastasis or cholangiocarcinoma) (P ≤ 0.001). The agreement between the T2* color map and dynamic images was moderate for all tumors (k = 0.544), good for tumors >2.0 cm (k = 0.666), and fair for tumors ≤2.0 cm (k = 0.334). With the gadoxetic acid-enhanced MRI used as a reference, the sensitivities of BOLD MRI (T2* color map) for displaying hypervascularity of HCC (categories of 1–3) were 81.0 % (n = 34/42) and 78.6 % (n = 33/42) for both observers.

Conclusion

Liver BOLD MRI has a potential to predict the vascular pattern of hepatic tumors.     

Detection of anomalous splenic artery aneurysms with three-dimensional contrast-enhanced MR angiography

Background

Aneurysms of the splenic artery which arise anomalously from the superior mesenteric artery are extremely rare but clinically important because of their life-threatening hemorrhage. Diagnostic imaging plays an important role in the diagnosis and conducting treatment strategy. The aim of this study was to evaluate the detection of anomalous splenic artery aneurysms with 3D contrast-enhanced MR angiography.

Methods

3D contrast-enhanced MR angiography was performed in six patients with anomalous splenic artery aneurysms.

Results

The mean diameter of six aneurysms was 3.9 cm. All of them were saccular and located at the origin of the splenic artery that arose anomalously from the root of the superior mesenteric artery. 3D contrast-enhanced MR angiography clearly demonstrated the aneurysm’s location, size, morphology, visceral arterial variations, and was superior to DSA in three-dimensional display of the aneurysm and its relationship with surrounding vessels and organs. Two patients underwent open vascular surgery and three endovascular procedure.

Conclusion

3D contrast-enhanced MR angiography is a noninvasive and accurate technique for diagnosis of anomalous splenic artery aneurysms. Its 3D anatomic information is very helpful for treatment planning. It can be used as one of the first choice examinations for anomalous splenic artery aneurysms.