Purpose: MR assessments of ovarian cystic lesions are usually based on morphological features, signal intensities and enhancement with contrast media. This study was performed to evaluate the usefulness of the steady-state free precession (SSFP) diffusion imaging of cystic ovarian lesions for analyzing cystic contents.
Materials and Methods: Sixty-one ovarian cystic lesions in 37 patients were examined. The diffusion-related coefficient (DRC) and the ratio of the relative apparent diffusion coefficient of the lesion to that of subcutaneous fat tissue (rADC_L/rADC_F) were calculated from SSFP diffusion images.
Results: The DRCs and the rADC_L/rADC_F ratios in endometrial cysts and in the fatty parts of dermoid cysts were significantly lower than in other cystic tumors.
Conclusion: SSFP diffusion imaging can be included in clinical practice to analyze ovarian cystic lesions within a short scan time; the DRC and the rADC_L/rADC_F ratio are useful for evaluating cystic contents.

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Purpose: To evaluate the feasibility of Interactive Scan Control (ISC), a new MR image navigation system, during percutaneous puncture in cryosurgery.
Materials and Methods: With the ISC system in place, percutaneous MR-guided cryosurgery was performed in 26 cases, with the ISC system being used in 11 cases (five renal tumors, three uterine fibroids and three metastatic liver tumors). The ISC system comprised infrared cameras and an MR-compatible optical tracking tool that was directly connected to a cryoprobe. Tumor sizes ranged from 1.2 cm (metastatic liver tumor) to 9.0 cm (uterine fibroid), for a mean size of 3.9 cm. With ISC, one to three cryoprobes with a diameter of 2 mm or 3 mm were advanced into the tumors with the guidance of an MR fluoroscopic image. Two freeze-thaw cycles were used for cryosurgery. During the cryosurgery, the formation of iceballs was monitored on MR images. Follow-up dynamic CT or MRI as well as physical examinations were conducted after two weeks and six weeks.
Results: Placement of probes was successfully performed under the control of the ISC system. During cryosurgery, engulfment of the tumors by iceballs was carefully monitored by MRI. Necrosis of the cryoablated area was confirmed in all renal tumors by follow-up dynamic CT. The size regression of the uterine fibroids was observed through follow-up MRI. Two of the three cases of metastatic liver tumor were ablated completely. Additional therapy for a residual tumor was performed on one patient with a metastatic liver tumor. A small amount of pneumothorax was the only complication found in a patient with a metastatic liver tumor.
Conclusion: MR-guided cryosurgery with this new navigation system was feasible with low morbidity and allowed for safe and accurate puncture with a cryoprobe.

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Purpose: A study was conducted to determine the possibility of evaluating the blood flow in cases of hypervascular hepatocellular carcinoma (HCC) by employing dynamic MRI with superparamagnetic iron oxide (SH U 555 A), which can be rapidly injected via an intravenous route.
Methods: Six patients with hypervascular HCC (23 nodules) served as the subjects. Dynamic MRI includes images obtained at precontrast and at 10 (perfusion phase), 60, 120, 180, 240, 300 and 600 s after the start of injection of SH U 555 A. CT hepatic arteriography (CTHA) and CT during arterial portography (CTAP) were used as the standards of reference, and these were performed in all patients three days after dynamic MRI. The signal changes were evaluated at each phase, especially at the perfusion phase from the viewpoints of a lesion-to-liver contrast-to-noise ratio (CNR) and visual examination.
Results: A total of 23 hypervascular HCC were detected on CTHA and CTAP. Of the 23 lesions, 17 were detected on SH U 555 A enhanced MRI. Incorrect timing during acquisition of the perfusion phase was considered in two cases with three lesions. Of 14 lesions, excluding two cases with incorrect timing, a reduction in the transient signal in the lesions at the perfusion phase was visually recognized in 10 lesions (71%). Significant differences were seen in tumor size between visible and non-visible tumors involving transient signal reduction (p<0.05). CNR gradually increased after rapidly decreasing in the perfusion phase.
Conclusion: SH U 555 A enhanced MRI is valuable in limited cases. Evaluation of tumor blood flow employing dynamic MRI with SH U 555 A is affected by tumor size and requires optimal timing of the perfusion phase.

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Purpose: To describe the morphologic and signal intensity characteristics of inflammatory adnexal masses in magnetic resonance (MR) images.
Materials and Methods: MR images of 15 patients with a total of 20 confirmed inflammatory adnexal masses were analyzed retrospectively.
Results: The findings obtained from MR imaging were as follows: lesions have ill-defined borders; ill-defined areas of high intensity signals surround the masses on T₂-weighted images; a “rim” at the innermost layer of the cyst wall exhibits high signal intensity on T₁-weighted images and low intensity on T₂-weighted images; secondary changes in the surrounding fat plane and bowel loops are extensive; and adhesions are dense. These findings reflect the basic characteristics of the inflammatory process, which are edema caused by increased permeability and highly vascularized granulation tissue caused by the strong tendency to repair.
Conclusion: MR imaging findings well reflect the basic pathological process of inflammation, and inflammatory adnexal masses are associated with relatively specific appearances in MR images.
MR imaging can be a problem-solving alternative in the diagnosis of inflammatory adnexal masses.

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Aim: To evaluate the potential role of carotid artery atherosclerosis plaque magentic resonance (MR) microimaging as magnetic resonance imaging (MRI) marker, ex vivo MR images were acquired at optimized parameters on 9.4T Bruker animal imager for occluded tissue resected by carotid endarterectomy (CEA) and corresponding histopathological analysis was made.
Methods and Materials: For imaging, CEA tissues of size 2-6 cm long and 0.5-1.5 cm wide, were transferred to 15 ml co-polymer laboratory culture tubes containing either 10% formalin in phosphate buffered saline (PBS) or in 50% glycerol in PBS. Imaging protocol was set at TE=30 ms, TR=1.5 s, matrix size=265×512, NEX=128, slice thickness=1 mm and in-plane resolution=0.1 mm for total sample size 2.5 cm. Soon after imaging done, carotid artery tissues were cut into 5-mm segments and processed for histological section for successive 5-micrometer slices. To compare morphology of 5 μm thin CEA section with that of 1 mm MR slices, registration was obtained between histologic sections and MR slices. Contrast and magnetic resonance relaxation characteristics were analyzed.
Results: Total carotid artery area computed by MR imaging was correlated with areas determined from histologic sections (r²=0.989, p=0.0001). For the lumen area, the correlation between MR images and histologic area was (r²=0.942, p=0.0001). Relaxation times and T₂ parametric images of different plaque components were determinant for contrast resolution. Scan parameters were optimized for fibrous cap and atheroma. Scan parameters were characteristic for comparison at 1.5T and 9.4T MR imagers.
Conclusion: The observed correlation validated MR microimaging to assess morphological features of carotid artery plaques and contrast resolution highlighted the potential of in vivo MR imaging as non-invasive MRI marker to monitor carotid artery plaque morphometry and plaque composition.

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Aneurysms involving the infrapopliteal arteries are unusual and in most cases result from trauma. Nontraumatic aneurysms of the infrapopliteal arteries are very rare. We report a case of an aneurysm of a branch of the posterior tibial artery. The clinical manifestations and the findings from magnetic resonance imaging and computed tomography led us to make a preoperative diagnosis of schwannoma. Histologic examination of the excised specimen suggested that this lesion was likely a true aneurysm.

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