Ultrasonography (US) is the initial imaging modality of choice for evaluation of patients in obstetrics. However, the results of US are not always sufficient. Magnetic resonance (MR) imaging, which uses no ionizing radiation, may be an ideal method for further evaluation. Although MR imaging is not recommended during the first trimester and use of contrast material is not recommended in pregnant patients, fast MR imaging is useful in various obstetric settings and can provide more specific information with excellent tissue contrast and multiplanar views. In pregnant patients with acute conditions, various diseases (eg, red degeneration of a uterine leiomyoma) may be diagnosed. MR imaging allows characterization of pelvic masses discovered during pregnancy and diagnosis of postpartum complications (eg, abscess, hematoma, ovarian vein thrombosis). In pregnant patients with hydronephrosis, MR urography can demonstrate the site of obstruction and the cause (eg, a ureteral stone). MR pelvimetry may be beneficial in cases of breech presentation. Contrast material-enhanced dynamic MR imaging allows one to evaluate the vascularity of a placental polyp, detect the viable component of a gestational trophoblastic tumor, and diagnose a uterine arteriovenous malformation. MR imaging enables diagnosis of rare forms of ectopic pregnancy and early diagnosis of ectopic pregnancy.

BACKGROUND AND PURPOSE:In the treatment of carotid atherosclerosis, the rate of stenosis and characteristics of plaque should be assessed to diagnose vulnerable plaques that increase the risk for cerebral infarction. We performed carotid black-blood (BB) MR imaging to diagnose plaque components and assess plaque hardness based on MR signals.

In patients with acute right-sided epigastric pain, jaundice, and a high fever, it is essential to accurately diagnose the cause of the symptoms, differentiate acute biliary disorders from nonbiliary disorders, and evaluate the severity of the disease. Gray-scale ultrasonography (US) and computed tomography (CT) are useful primary imaging modalities, but their results are not always conclusive. Magnetic resonance (MR) imaging, including MR cholangiopancreatography, can be a valuable complement to US and CT when additional information is needed. MR images have excellent tissue contrast and can provide more specific information, allowing diagnosis of complications that arise from acute cholecystitis, such as empyema, gangrenous cholecystitis, gallbladder perforation, enterocholecystic fistula, emphysematous cholecystitis, and hemorrhagic cholecystitis. In addition, causes of obstructive jaundice, acute suppurative cholangitis, and hemobilia can be clearly demonstrated with multisequence MR imaging. Single-section MR cholangiopancreatography and heavily T2-weighted imaging, in combination with fat-suppressed T1- and T2-weighted imaging, provide comprehensive and detailed information about the biliary system around the obstruction site, biliary calculi, inflammatory processes, purulent material, abscesses, gas, and hemorrhage. Contrast-enhanced MR imaging is useful for evaluation of the gallbladder wall; lack of enhancement and disruption of the wall may be findings specific for gangrenous cholecystitis and gallbladder perforation, respectively.

Purpose:To investigate whether the vessel wall MRI of carotid arteries would differentiate at-risk soft plaque from solid fibrous plaque by identifying liquid components more accurately than color Doppler ultrasonography (US). Materials and Methods:This study included 54 carotid arteries in 54 consecutive patients who underwent carotid endarterectomy. MRI was performed using black-blood fatsuppressed (FS) T1-and FS T2-weighted TSE sequences. A total of 68 major segments of the 54 carotid plaques were grouped into four MR categories based on signal intensity index (SII). MR criteria used for the diagnosis of plaque vulnerability were: at-risk soft plaque including a segment of liquid component (category A or B), solid fibrous plaque (category C or D). The MR and US findings were compared with histopathological findings of endarterectomy specimens. Results:Intraoperative findings and microscopic examination of endarterectomy specimens revealed 24 at-risk soft plaques and 30 solid fibrous plaques. The sensitivity, specificity, and accuracy for diagnosing at-risk soft plaque are 96%, 93%, and 94% for MR, and 75%, 63%, and 69% for color Doppler US, respectively. The slice-by-slice MR evaluation of carotid wall also revealed detailed information of plaque segments and correlated well with the features of corresponding histologic sections. Conclusion:Vessel wall MRI with MRI category could have a potential to more accurately diagnose an at-risk soft plaque predominantly composed of liquid components in comparison with color Doppler US.

Purpose: To investigate the feasibility and usefulness of diffusion-weighted magnetic resonance imaging in the detection of testicular torsion. Materials and Methods:Institutional Review Board approval and informed consent from all participants were obtained. Consecutive 28 patients with acute scrotal symptoms were included in this study. Fat-suppressed T2-weighted, dynamic subtraction contrast-enhanced, and diffusion-weighted images were obtained in the coronal plane with a 1.5 T MR unit. An apparent diffusion coefficient (ADC) map was reconstructed from the diffusion-weighted images obtained with b-factor of 0 and 800 s/mm 2 . Comparisons of ADC values between the affected and nonaffected testes were performed with Mann-Whitney's U-test.Results: Diffusion-weighted and ADC images with diagnostic quality were obtained in 23 out of the 28 patients (82%). In testicular torsion (n ¼ 9), the mean ADC value of the twisted testes was significantly lower than that of the nonaffected testes (0.750 6 0.297 vs. 1.017 6 0.165 Â 10 À3 mm 2 /sec, P < 0.05). In other scrotal disorders (n ¼ 14), there was no significant difference in the mean ADC value of the testes between the affected and nonaffected side (P ¼ 0.655). The affected-to-nonaffected ratio of ADC value was significantly lower in testicular torsion than that in other scrotal disorders (P < 0.05).Conclusion: Diffusion-weighted imaging of the scrotum with testicular ADC measurement can allow for the detection of testicular torsion without any use of contrast media.

PurposeTo investigate the usefulness of targeted biopsy strategy based on apparent diffusion coefficient (ADC) maps in the detection and localization of prostate cancer.Materials and MethodsInstitutional review board approval and informed consent from all participants were obtained. This study included 1448 consecutive patients suspected of having prostate cancer based on PSA level, who were divided into two groups: Group A included 890 patients with low-ADC lesions who underwent targeted and systematic biopsies; Group B included 558 patients with no low-ADC lesions who underwent only systematic biopsies. The cancer detection rates (CDR) of each group, positive predictive value (PPV), and negative predictive value (NPV) of ADC maps were calculated.ResultsThe CDR was 70.1% for Group A, higher than those for overall patients (48.1%) and for Group B (13.1%) with significant difference (P < 0.001). In the serum, PSA range from 4 to 20 ng/mL, the CDR was higher for the Group A than for the Group B and overall patients with significant differences. PPV and NPV of MR findings were 70.1% and 86.9%, respectively. Especially, the PPV of the MR findings for the anterior portion was as high as 90.1%. Among the false negatives of MR findings, Gleason score proved 6 or smaller in 79.5%, and positive core number was merely one or two in 80.8%.ConclusionThe targeted biopsy strategy based on ADC maps can be useful in the detection and localization of prostate cancer with high PPV. J. Magn. Reson. Imaging 2012;35:1414–1421. © 2012 Wiley Periodicals, Inc.

Atherosclerotic carotid plaque represents a major cause of cerebral ischemia. The detection of vulnerable plaque is important for preventing future cardiovascular events. The key factors in advanced plaque that are most likely to lead to patient complications are the condition of the fibrous cap, the size of the necrotic core and hemorrhage, and the extent of inflammatory activity within the plaque. Magnetic resonance (MR) imaging has excellent soft tissue contrast and can allow for a more accurate and objective estimation of carotid wall morphology and plaque composition. Recent advances in MR imaging techniques have permitted serial monitoring of atherosclerotic disease evolution and the identification of intraplaque risk factors for accelerated progression. The purpose of this review article is to review the current state of techniques of carotid wall MR imaging and the characterization of plaque components and surface morphology with MR imaging, and to describe the clinical practice of carotid wall MR imaging for the determination of treatment plan.

Purpose: To determine whether emergency subtraction dynamic contrast-enhanced MR imaging (DCE-MRI) in combination with T2-and T2*-weighted imaging of the testis is useful in the evaluation of patients with testicular torsion. Materials and Methods:Fourteen patients with surgically proven testicular torsion were examined using preoperative emergency MRI, including T2-weighted, T2*-weighted, and DCE-MRI. The affected testis was examined histologically in eight patients who underwent orchiectomy, and by postoperative follow-up MRI in six patients who underwent orchiopexy. The diagnostic criteria for testicular torsion and detection of hemorrhagic necrosis in the affected testis in emergency MRI were decreased or no perfusion in DCE-MRI and a spotty and/or streaky pattern of low or very low signal intensity in T2-and T2*-weighted images. The intraoperative findings and clinical outcomes were also compared. Results:The histological findings and follow-up MR images revealed total or partial necrosis of the affected testis in 10 of the 14 patients. In the diagnosis of complete torsion, the sensitivities were 100% for DCE-MRI and 75% for T2-and T2*-weighted imaging. In the detection of testicular necrosis, T2-and T2*-weighted imaging showed the highest accuracy (100%), followed by 12-hour time from onset (93%), intraoperative findings (79%), and DCE-MRI (71%). Conclusion:Emergency MRI can help diagnose testicular torsion and detect testicular necrosis when DCE-MRI is used in combination with T2-and T2*-weighted images.