Yutaka Araki

MRI of head injury using FLAIR

Abstract We studied the utility of fluid-attenuated inversion-recovery (FLAIR) MRI in the investigation of head injury. We examined 56 patients with head injuries with T2-weighted spin-echo (SE) and FLAIR sequences. In all cases, the sensitivity of FLAIR images to equal or superior to that of conventional SE images to the traumatic lesions. In 9 cases, central diffuse axonal injury of the fornix and corpus callosum could be seen only on sagittal FLAIR images.

MRI of the brain in diabetes mellitus

We studied the MRI appearances of the brain in 159 patients with diabetes mellitus (DM) and 2566 agematched individuals without DM (controls). The images were reviewed for cerebral infarcts, hemorrhage, atrophy and subcortical arteriosclerotic encephalopathy. Cerebral atrophy was significantly more frequent in patients with DM than in controls (P>0.005) from the sixth to the eighth decade. The frequency of atrophy was 41.2% in the 6th decade, 60.0% in the 7th and 92.3% in the 8th decade in DM, and 19.8%, 38.9% and 56.8% respectively in controls. Unexpectedly, there was no statistically significant difference in the incidences of cerebrovascular diseases at any age.

Long-term results of lipiodol-transcatheter arterial embolization with cisplatin or doxorubicin for unresectable hepatocellular carcinoma.

The long-term effects of Lipiodol-transcatheter arterial embolization (Lp-TAE) combined with cisplatin (CDDP) or doxorubicin (ADM) on unresectable hepatocellular carcinoma (HCC) were analyzed. Eighty-four consecutive patients with unresectable HCC were treated with TAE. Of the 84, 38 patients were treated with CDDP-Lp-TAE (CDDP group), whereas the remaining 46 patients were treated with ADM-Lp-TAE (ADM group). No significant difference in characteristics of patients and tumors was noted between the groups. CDDP (50 mg) or ADM (20-50 mg) was administered with Lp followed by embolization of the feeding arteries using gelatin sponge particles. The mean number of TAE treatments was 3.3 in the CDDP group and 1.9 in the ADM group (p < 0.01). The 5-year overall survival rates of the CDDP group and the ADM group were 19% and 6%, respectively. The overall survival rate of the CDDP group was significantly higher than that of the ADM group (p < 0.05). No serious side effects were observed in either group. CDDP-Lp-TAE improved the prognosis of unresectable HCC compared with ADM-Lp-TAE, which may be attributable to the fact that CDDP-Lp-TAE treatment could be repeated more times than ADM-Lp-TAE.

Benign fibrous histiocytoma of the femur: review of three cases

Abstract Objective. Benign fibrous histiocytoma is a tumor with histologic features similar to those of xanthofibromas, which include fibrous cortical defects and nonossifying fibromas, but with different clinical features. This study investigated the findings of benign fibrous histiocytoma on various imaging modalities. It emphasized the importance of clinical and imaging features as well as histologic findings in establishing the diagnosis. Design. We reviewed three cases of benign fibrous histiocytoma of the femur that had been diagnosed histologically as (fibro)xanthoma during a retrospective analysis of 187 primary benign and malignant bone lesions. Patients. All the patients were middle-aged women with various knee complaints. Results and conclusions. Radiologically, the lesions were all lytic with well-defined geographic margins and sclerotic rims. The tumors arose within the medullary cavity in the distal metaphysis of the femur and involved the epiphysis. CT showed lytic destruction with well-defined marginal sclerosis. T1-weighted MR images showed that the lesions had predominantly the same signal intensity as that of skeletal muscle. The lesions were hypovascular on angiography. Bone scintigraphy showed moderately increased uptake. It was concluded that multiple images as well as clinical features can be useful in differentiating benign fibrous histiocytoma from fibroxanthoma, giant cell tumor, and other fibrohistiocytic tumors of bone.

Usefulness of magnetic resonance imaging for detecting intrasubstance tear and/or degeneration of lateral discoid meniscus

In order to determine the usefulness of magnetic resonance imaging (MRI) for detection of intrasubstance tears or degeneration of the lateral discoid meniscus, we compared findings obtained with MRI with those of histological examination. Sixty-four symptomatic lateral discoid menisci were studied using MRI before surgical treatment. Of these, 18 (28%) met the criteria that MRI signals did not extend to the surface and that no visible tears were observable at arthroscopy. Findings of intrameniscal regions of high signal intensity and flattening in shape on MR images were found to represent intrasubstance tears or degeneration not detected at arthroscopy. Our findings thus demonstrate that MRI is more sensitive than arthroscopy in the detection of intrasubstance pathologies of the lateral discoid menisci.

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.

Iodine concentrations in the rat kidney measured by x-ray microanalysis Comparison of concentrations and viscosities in the proximal tubules and renal pelvis after intravenous injections of contrast media

Purpose: To measure the iodine concentrations in the proximal tubules and renal pelvis after i.v. injections of contrast media (CM) at 1600 mg I/kg b.w., using a micro-puncture technique and X-ray microanalysis Material and Methods: The correlation between the viscosity of each CM and its iodine concentration was evaluated and the viscosity of the fluid in the proximal tubule and renal pelvis was estimated in rats Results: After iotrolan injection, the iodine concentration in the proximal tubular fluid had increased to values about three times higher than those reached with diatrizoate, iohexol and ioxaglate. Similarly, iotrolan tended to produce a higher iodine concentration in the renal pelvis than did the other CM. the urine viscosity in the renal pelvis was much higher after the iotrolan injection than after the other CM injections Conclusion: High urine viscosity after iotrolan injection can at least partly explain our previous findings of a prolonged increase in tubular hydrostatic pressure and a prolonged decrease in the single nephron glomerular filtration rate after administration of this CM

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.

MRI of paraganglioma of the cauda equina

Paragang l ioma is a turnout of the accessory organs of the per ipheral nerve system or paraganglia: P h a e o c h r o m c y t o m a of the adrenal medul la is the mos t typical paragangl ioma [1, 2]. Ex t ra -adrena l paragangl iomas occur mos t of ten in the carot id body, glomus jugulare, medias t inum, and para-aor t ic region. Central nervous system locations include the pet rous ridge, pineal region, and sella turcica. Paragangl ioma of the cauda equina was first described in 1970 [3], and since then only 54 cases have been repor ted [1-9]. To our knowledge, there has been only one repor t of M R I of a pa ragang l ioma of the cauda equina [4]. Case report

Ovarian fibroma of high signal intensity on T2-weighted MR image

Abstract. It has been reported that ovarian fibromas display low signal intensity on both T1- and T2-weighted magnetic resonance images. We report an ovarian fibroma exhibiting low signal intensity on a T1-weighted image and high signal intensity on a T2-weighted image. Microscopically pronounced myxomatous changes were shown in the fibroma. The signal intensity of ovarian fibromas differs with the degree of myxomatous change.