A pitfall in detection of intracranial unruptured aneurysms on three-dimensional phase-contrast MR angiography.

We report three cases of intracranial unruptured aneurysm evaluated with MR angiography using both three-dimensional time-of-flight and three-dimensional phase-contrast techniques. It has been said that the phase-contrast technique has advantages over the time-of-flight technique in the detection of intracranial aneurysms. However, in our three cases, three-dimensional time-of-flight MR angiography clearly showed the intracranial unruptured aneurysms, but three-dimensional phase-contrast MR angiography failed to show them.

Acetazolamide challenge for three-dimensional time-of-flight MR angiography of the brain.

PURPOSE: We compared three-dimensional time-of-flight MR angiograms obtained before and after acetazolamide administration to evaluate whether use of this drug could improve visualization of small peripheral intracranial arteries and atherosclerotic stenosis. METHODS: For evaluation of small peripheral arteries, 10 patients with clinical diagnosis of ischemic cerebrovascular disease and 10 healthy volunteers were investigated, and for evaluation of stenosis, another 6 patients were investigated. Vascular images were obtained by three-dimensional time-of-flight MR angiography. After a baseline scan, 17 mg/kg acetazolamide was injected intravenously and the second scan was performed 20 minutes later. RESULTS: Several small peripheral arteries that had not been seen on the baseline images were visible on the acetazolamide images without any augmentation of the background signals. Stenotic lesions in the main trunks of the major cerebral arteries were detected more clearly on acetazolamide images. CONCLUSIONS: Acetazolamide improves visualization of small peripheral intracranial arteries and sensitivity in detecting atherosclerotic stenosis in the main trunk of major cerebral artery by three-dimensional time-of-flight MR angiography without changing MR apparatus and software.

MR diagnosis of discoid lateral menisci of the knee.

OBJECTIVE: To establish explicit criteria for MR imaging diagnosis of discoid lateral menisci of the knee. SUBJECTS: Materials included surgically proved 38 discoid lateral menisci and 36 normal lateral menisci of adult patients. A discriminant analysis was used to identify the optimal cut-off points of the following eight parameters: (1) transverse width of a lateral meniscus on the coronal image at the midportion of a meniscal body; (2) ratio of transverse width between a lateral meniscus and a tibia; (3) height of the lateral margin of a lateral meniscus; (4) difference in height between lateral and medial menisci; (5) transverse area of a lateral meniscus; (6) the number of consecutive sagittal slices demonstrating continuity of the meniscus between the anterior and posterior horns (bow tie appearance); (7) height of the anterior horn of a lateral meniscus on the sagittal image; (8) height of the posterior horn of a lateral meniscus on the same sagittal image. RESULTS: The transverse width of a lateral meniscus on the coronal image was the best parameter, with a cut-off point of 14 mm. Using this criterium, 33 knees of 38 discoid lateral menisci and all 36 normal menisci were correctly identified, yielding an overall accuracy of 93%. CONCLUSION: A discoid lateral meniscus should be present if the transverse width of a lateral meniscus at the midportion of a meniscal body exceeds 14 mm, independent of the tibial width.

MR imaging of meniscal tears with discoid lateral meniscus.

OBJECTIVE: To study MR findings of meniscal tears with discoid lateral menisci (DLMs) and to evaluate the incidence and accuracy of MRI compared to arthroscopical surgery. MATERIAL AND METHODS: MR appearances of surgically proved torn discoid lateral menisci (DLM) were studied in 57 knees (40 patients). They were all performed with a 1.5T MR before surgery. MR sequences included T1- and T2* weighted images on both coronal and sagittal planes and 3D-axial images with a slice thickness of 0.7 mm. RESULT: Of 57 DLMs, there were 32 complete DLMs and 25 incomplete DLMs. Twenty-five of 32 complete DLMs had tears; including seven with intrasubstance tear, five with radial tear, five with other kinds of tears and eight with severe tears involving whole meniscus. On the other hand, 13 of 25 incomplete DLMs had tears; including two with intrasubstance tear, six with radial tear, four with other kinds of tears and one with severe tears. All DLMs were correctly diagnosed on MR images. Twenty-seven of 38 tears with DLM were correctly identified on conventional 2D MR images. This yielded 71.1% sensitivity, 100% specificity and 80.7% overall accuracy. When adding axial 3D MR images to 2D MR images, 36 of 38 tears were correctly diagnosed. A combination of both techniques yielded a sensitivity of 94.7% and a specificity of 100%. Ten of 11 radial tears with DLM were correctly identified on 3D axial images, where only three of them could be diagnosed on conventional 2D images. Eight of nine intrasubstance tears were correctly identified on 3D axial images, where six of them could be diagnosed on conventional 2D images. CONCLUSION: DLMs had a much higher incidence of meniscal tears than normally shaped lateral menisci and MR is the only modality of choice to evaluate them before surgery. Especially 3D axial MR images were quite useful in the detection of intrasubstance and radial tears often associated with DLMs.

MR imaging of acute disseminating encephalomyelitis.

We present a case of acute disseminating encephalomyelitis (ADEM) diagnosed on MR imaging. MR imaging accurately identified the location of the ADEM lesions in the spinal cord and brain.

MRI of fibrous cortical defect of the femur.

The MR imaging findings of 10 cases of fibrous cortical defect of the femur are presented. Although surgical biopsy was not available in the 10 cases, clinical follow-up confirmed the diagnosis. Most of the lesions were located on the posteromedial aspect of the distal femur, corresponding to the site of attachment of the extensor tendon of the adductor magnus muscle or the medial head of the gastrocnemius. They were oval in shape, and their diameter ranged from 29 x 15 mm to 8 x 6 mm, with an average of 14 mm. With MR, most of the fibrous cortical defects were imaged with iso-signal intensity to muscle on T1-weighted images and high signal intensity on T2*-weighted images. They were invariably surrounded by low signal intensity rims on both sequences, representing marginal sclerosis. The appearance seemed to be sufficiently diagnostic to obviate the need for biopsy.

MR imaging of pigmented villonodular synovitis of the knee.

Six cases of pigmented villonodular synovitis (PVNS) of the knee are presented. MR imaging and surgical proof were available in all cases. Three of the six cases showed the diffuse form, and the other three cases the localized form. The MR appearance of PVNS varied, presumably according to the relative proportion of pathological components. It most commonly consisted of scattered low signal intensity areas representing hemosiderin deposition in hypertrophied synovium on T2(*)-weighted images, and dotted areas of low signal intensity, presumably resulting from fibrous components of the lesion, on T1-weighted images. The latter finding is described for the first time in this report. Two cases were associated with osteoarthritis. In the remaining four cases, the osseous structures, cruciate ligaments, and menisci were normal. MR imaging was of great use in the detection of PVNS. For the first time, a preoperative diagnosis of PVNS of the knee joint could be made by MR imaging.

MRI of symptomatic sacral perineural cyst.

Sacral perineural cyst is a relatively rare condition. To our knowledge, reports of MR findings associated with sacral perineural cyst have been limited to only six cases. We present for the first time high field MR findings in a case of sacral perineural cyst. The cyst appeared as a cystic lesion in the sacral spinal canal and had intermediate signal intensity on T1W images and high signal intensity on T2*W images compared with CSF. Slight erosion remodeling of the sacrum was also seen anteriorly. Our case was symptomatic and present with radiculopathy (sciatic pain). Surgical treatment was done to result in dramatic improvement of the sciatic pain.

Case report: MR appearance of hemangiopericytoma of the thigh.

We report a case of hemangiopericytoma in the thigh of a 42-year-old woman. CT examination depicted a peripherally enhanced, multicystic mass without calcification. On T1-weighted images of MRI, the mass showed slightly high signal intensity relative to muscle, with the exception of the lower pole, which showed high signal intensity. On T2*-weighted images, the mass showed high signal intensity and cystic appearance. The lower pole showed low signal intensity on T2*-weighted images and was thought to be intratumoral hemorrhage. Low signal intensity structures on both T1- and T2*-weighted images were observed within and around the mass. They were thought to be dilated vessels, although this was not confirmed at surgery. Hemangiopericytoma should be considered in the differential diagnosis of a tumor in the thigh when MR images show the mass with slightly high signal intensity on T1-weighted images, intratumoral hemorrhage, and flow voids within or adjacent to the tumor.

[Doses of epirubicin used in oily chemoembolization of hepatocellular carcinoma].

Epirubicin (EPIR), an anticancer agent, has recently been used with increasing frequency in transcatheter oily chemoembolization (TOCE) of hepatocellular carcinoma. We conducted a dose-finding study of EPIR with regard to its safety. One hundred thirty-four patients were divided into five groups according to the EPIR doses (mg/m2), Group A (< 30 mg/m2), Group B (> or = 30 - < 40 mg/m2), Group C (> or = 40 - < 50 mg/m2), Group D (> or = 50 - < 60 mg/m2), and Group E (> or = 60 mg/m2). The number of leukocytes decreased at 2 weeks but recovered at 4 weeks with no significant differences among the groups. However, there were significantly fewer leukocytes in Group E than in Groups A to D. There were no significant differences among the groups in either the number of erythrocytes or platelets. The number of platelets tended to remain at increased levels even at 4 weeks. Liver function as represented by GOT, GPT, LDH, and total bilirubin was not aggravated, but tended to improve. GOT and LDH in Groups D and E, in particular, improved significantly at 4 weeks, probably because of the antitumor effect of TOCE. These results suggest that EPIR can be administered up to 50 mg/m2 for TOCE.

[Chemoembolization].

Chemoembolization is a technique by which the blood flow in the artery feeding a tumor is arrested and, at the same time, an antitumor agent is delivered in a high concentration to the target site in anticipation of a synergistic antitumor effect. Usually, this is a transcatheter technique. The embolic materials used to arrest the blood flow include gelatin sponge, Lipiodol, microcapsule, albumin microsphere, degradable starch microsphere and the like. Since the gelatin sponge and Lipiodol are available on the market, transcatheter oily chemoembolization (TOCE) using these two materials was performed in cases of hepatic tumor. In many cases of TOCE, adriamycin was used as an adriamycin solution Lipiodol mixture (adriamycin-in-oil emulsion). The cumulative survival rates for 100 patients with unresectable hepatoma treated by TOCE were 53.8% for one year and 36.5% for two years. Thus, improvement was observed in comparison with the cumulative survival rates of 104 patients who underwent hepatic embolization without Lipiodol (1 year, 45.2%, 2 years, 16.3%). Adriamycin-in-oil emulsion retained in the tumor as microemboli brings about the slow-releasing effect of adriamycin. The effect was demonstrated in the blood and tissue concentrations of adriamycin following TOCE.

[Oily chemoembolization of hepatoma].

Since 1983 we have performed transcatheter oily chemoembolization (TOCE) using adriamycin (40-100 mg), Lipiodol (5-20 ml) and Gelfoam in the treatment of 100 cases with unresectable hepatocellular carcinoma. Adriamycin was dissolved in a fluid equal in specific gravity to Lipiodol and the adriamycin solution was mixed with 3 volumes of Lipiodol, making an adriamycin-in-oil emulsion (AOE). After TOCE, the blood concentration of adriamycin was obviously lower than that after one-shot injection because of the slow release of adriamycin from the AOE. Also, in cases of hepatic resection after TOCE, there was a clear difference in the adriamycin concentration between the tumor and the normal hepatic tissue. The cumulative survival rates for the 100 patients treated by TOCE were: 6 months 81.9%, 1 year 53.8% and 2 years 36.5%. Thus, improvement was found in comparison with the cumulative survival rates for 104 patients who underwent hepatic embolization without Lipiodol, which were 6 months 67.4%, 1 year 45.2% and 2 years 16.3%. AOE retained in the tumor as microemboli brings about the slow-releasing effect of adriamycin. Furthermore, by adding the effect of Gelfoam embolization, TOCE has a strong antitumor effect.

[Mesenteric desmoid found after surgery of familial polyposis coli; a case report].

A 51-year-old woman manifested with complaints of an abdominal mass 5 years after colectomy. In comparison with the cases previously reported, this desmoid had lower CT value (20-30 HU), and more vascularity with neovascularization on angiography. These findings seem to reflect the characteristic of much cellularity and malignancy of the desmoid.

Vascular supply with angio-CT for superselective intra-arterial chemotherapy in advanced maxillary sinus cancer.

Recently popularised, the combined angiography and CT (angio-CT) system is useful for correctly identifying the feeding arteries and their perfusion in various organs. We applied this system for advanced maxillary cancer to expose its feeding arteries and their supplying territories. In addition to the maxillary artery, extramaxillary feeding arteries were usually observed, including the ophthalmic, accessory meningeal, facial, transverse facial and ascending palatine arteries. These extramaxillary feeding arteries exhibited uniform tendencies, depending on the site of extramaxillary tumour extension.