Effects of microwave tissue coagulation on the livers of normal rabbits: a comparison of findings of image analysis and histopathological examination

The livers of normal rabbits were subjected to microwave tissue coagulation (MTC), and comparison was made of the subsequent time-course changes in tissue observed on MRI, CT and histopathological examination. 16 rabbits were used. MTC was performed with a 21 gauge needle electrode inserted into the liver at laparotomy. 1-2 h after thermal coagulation, a region with slightly lower attenuation than that of surrounding normal liver parenchyma was observed on CT, and no enhancement was detected. With MRI, change from high signal intensity to iso-signal intensity from the inner zone to the margin was found on T1 weighted images (T1WI), and heterogeneous high signal intensity was observed on T2 weighted images (T2WI). On Gd-DTPA enhanced MRI, no enhancement occurred. 1-4 weeks after coagulation, the cellular structure at the site of coagulation was lost on histological examination, and the tissue became necrotic. On CT, homogeneous water density was observed, and no enhancement was detected. With MRI, regions of iso- or slightly low signal intensity were observed on T1WI, and regions of heterogeneous high to low signal intensity were seen on T2WI. After 1 week, a granulation layer consisting mainly of fibrous tissue developed, and a ring-shaped enhancement was observed in the low signal intensity region on T1WI and in the high signal intensity region on T2WI. The ring-shaped enhancement was also noted on CT. MRI appears to be useful for observation of time-course changes following MTC therapy because of its sensitivity in the detection of tissue changes.     

Transient osteoporosis of the knee

The MR findings in transient osteoporosis of the knee have been described as showing a diffuse area of decreased signal intensity (relative to normal bone marrow) on T1-weighted images and increased signal intensity on T2-weighted images. We report a case of transient osteoporosis, in which MRI showed a crescentic area of abnormal signal intensity in the posterior portion of the lateral femoral condyle, which was bordered by a rim of low signal intensity, best seen on the T2-weighted images. This abnormality was shown to resolve on follow-up MR scans.     

MR imaging of hepatocellular carcinoma following microwave coagulation therapy

MRI was performed in 13 patients who had microwave coagulation therapy (MCT) for hepatocellular carcinoma. Six of them underwent surgery after MRI. The area (including tumor) treated by MCT showed low to high intensity on T1WI, and low to isointensity on T2WI. No enhancement was obtained on dynamic MRI. Histologically, this area was supposed to be coagulation necrosis. On T1WI, only tumor showed high intensity within the MCT area in 8 patients, and nearly uniform intensity was observed in 5 patients. Histologically, residual cell nuclei were observed in the former, and nearly uniform coagulation necrosis in the latter. The marginal part of the MCT area exhibited low intensity on T1WI, and high intensity on T2WI. Strong enhancement was obtained on dynamic MRI, and histologically, granulation tissue was noted. In the hepatic parenchyma around the MCT area, a ring-or wedge-shaped high intensity part was observed in 7 patients on T2WI, and that part was enhanced on dynamic MRI. This finding was considered to reflect changes such as hepatic hyperperfusion. In terms of the capability of visualizing residual tumor after MCT, MRI was superior to CT. Furthermore, a clear distinction was seen between the MCT area and non-MCT area on T2WI and dynamic MRI. Thus, MRI was useful in the determination of additional therapy.     

Increased gene transfer into human CD34+ progenitor cells using retroviral vectors produced by a canine packaging cell line

Magnetic resonance imaging (MRI) was used in 13 patients with peripheral lymphedema and 2 patients with extensive cavernous lymphangioma of the limb for the purpose of evaluating its role in diagnosis of lymphatic disorders. In chronic lymphedema, MRI showed deformity of lymphatics at different tissue levels. In the subcutis, MRI characteristically displayed diffuse edema or a honeycombed pattern consistent with reticular lymphangiectasis and "lakes" with a marked increase in signal intensity with T2-weighted imaging. In lymphedema hyperplasia and chylous reflux, MRI depicted dilated retroperitoneal lymphatic collectors and lumbar trunks. In cavernous lymphangiomatosis, MRI demonstrated a prominent lattice-like pattern which had lower signal intensity on T1-weighted imaging and higher intensity on T2-weighted imaging. The findings of MRI are valuable not only for accurate assessment of lymphatic dysplasia syndromes but also provide a blueprint for treatment options.     

Cystic mesothelioma of the peritoneum

We report a case of cystic mesothelioma of the peritoneum (CMP), a rare tumor. The magnetic resonance imaging (MRI) findings and the histochemical features were studied. The patient was an 18-year-old women who presented with upper abdominal pain. Abdominal ultrasonography and computed tomography showed a well defined cystic mass with a solid papillary projection in its lumen. MRI of the cyst showed high intensity on T2- and proton weighted images and low intensity on T1-weighted images, and the solid projection showed low intensity on T2- and proton-weighted images and slight low intensity on T1-weighted images, on which it was well enhanced. The lesion was suspected to be a benign cyst, such as a hemangioma, lymphangioma, or a splenic or pancreatic cyst. Complete surgical resection was performed. The resected specimen consisted of a unilocular cystic mass, with a solid projection, weighing 260 g and measuring 10 cm in diameter. The final diagnosis, arrived at by histopathological examination, was low-grade malignant CMP. The tumor cells were strongly positive for keratin, weakly positive for vimentin, and negative for epithelial membranous antigen. The patient is now well and symptom-free with no recurrence 19 months after operation. CMP is a rare tumor; only 12 cases have previously been reported in Japan.     

Detection of glomus tumor of the finger by dedicated MRI at 0.1 T

Three glomus tumors of the fingers were detected using a dedicated hand and wrist low field (0.1 T) MR imager equipped with solenoidal coils allowing a FOV of 2 cm. Three-dimensional T1-, T*2-, or T2-weighted images were used (8 contiguous slices of 2 mm thickness). Glomus tumors had low or intermediate signal intensity (2 cases) or no signal (1 case) on T1-weighted images. On T*2- or T2-weighted images they had high signal intensity. MRI findings correlate well with surgery and biopsy.     

A case of macrocystic cervical neurinoma diagnosed by MRI with Gd-DTPA

The authors report a rare case of a large cystic cervical neurinoma. A 45-year-old female was admitted to our clinic because of motor weakness of the right upper extremity, numbness of the right fingers and right posterior cervical pain. Metrizamide CT myelography demonstrated the outline of a low density mass. MRI showed a mass revealing low signal intensity on T1-weighted image, high signal intensity on T2-weighted image and marginal enhancement on contrast image with Gd-DTPA. The mass which was diagnosed as cystic tumor, was located in the intradural extramedullary space between C4 to C5 segments. After C4 through C5 laminectomy, the tumor was found to originate from the C5 anterior motor root. The tumor consisted mostly of a cystic part with a very thin solid compartment beneath the capsule. Postoperative course of the patient was uneventful. Although spinal neurinoma is one of the most common spinal tumors, an almost completely degenerated large cystic spinal neurinoma is extremely rare. MRI with Gd-DTPA was useful for the diagnosis of the cystic neurinoma by clearly enhancing the margin of the tumor.     

MR imaging findings of the femoral marrow in myelodysplastic syndrome

MR imaging of the femoral marrow was performed in 30 patients with myelodysplastic syndrome (MDS), 11 cases of which evolved to acute myeloid leukemia (AML). The MRI appearance was classified into five patterns: 1) fatty marrow; 2) faint signal; 3) nodular pattern; 4) heterogeneous infiltration; and 5) diffuse infiltration. For each type of MDS, MRI patterns of the femoral marrow were evaluated and compared with those in normal subjects as well as in patients with aplastic anemia. Signal intensity alteration, a low signal on T1-weighted SE image and a high signal on STIR image, began in the proximal femoral marrow almost symmetrically in patients with MDS. The area of abnormal signal intensity tended to gradually extend towards the distal portion of the femur as the disease progressed. MRI patterns of the femoral marrow correlated with marrow cellularity, and diffuse marrow infiltration was noted in patients with a more advanced type of MDS or with severe anemia. There were limitations to making an accurate diagnosis of the MDS type on the basis of the MRI pattern. Progression of the MRI appearance in the course of MDS was thought to be a sign suggesting evolution to AML. It was difficult to differentiate hypoplastic MDS from aplastic anemia, although the nodular pattern was commonly seen in the latter disease.     

Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise

A case of malignant fibrous histiocytoma (MFH) in a 29-year-old man was reported. CT scans revealed an iso density mass which was homogeneously enhanced by contrast medium. MRI demonstrated that the right frontal tumor showed slight low signal intensity in T1-weighted image, and iso signal intensity in T2-weighted image. Gadolinium-enhanced T1-weighted image showed a homogeneously enhanced multinodular tumor. Right carotid angiogram revealed a tumor stain fed by the precentral artery. On operation, en-bloc resection was performed successfully. Postoperatively, local irradiation of 60Gy was performed. Microscopically, fibroblast-like cells arranged in storiform pattern were observed, and bizarre multinucleated giant cells were also observed. Ki-67 labelling index was 54%. We considered the tumor was a MFH and arose from an intracerebral mesenchymal tissue. We reviewed some literature and briefly discussed clinicopathological features and therapy of intracranial MFH.     

Osteogenic sarcoma: noninvasive in vivo assessment of tumor necrosis with diffusion-weighted MR imaging

PURPOSE: To evaluate diffusion-weighted magnetic resonance (MR) imaging for detecting tumor necrosis in an animal model of osteogenic sarcoma. MATERIALS AND METHODS: Twelve rats with osteogenic sarcoma underwent T1-weighted unenhanced and gadolinium-enhanced spin-echo and diffusion-weighted spin-echo MR imaging. Histologic correlation was performed. Signal intensities, T2 relaxation times, normalized apparent diffusion coefficients, and relative signal intensity increases were calculated. RESULTS: On diffusion-weighted images, necrotic tumor showed low signal intensity (mean normalized apparent diffusion coefficient, 0.46 +/- 0.20 [1 standard deviation]), indicating rapid diffusion of water molecules as a result of loss of membrane integrity, while viable tumor showed high signal intensity (mean normalized apparent diffusion coefficient, 0.16 +/- 0.05; P < .0001). Differences in the T2 relaxation times and relative signal intensity increases between viable and necrotic tumor were not statistically significant. CONCLUSION: Normalized apparent diffusion coefficients are more accurate in differentiating between viable and necrotic tumor than are T2 relaxation times or relative signal intensity increases on contrast-enhanced images. Signal intensity overlap between viable and necrotic tumor on gadolinium-enhanced images may be caused by the small molecular size of the agent, which permeates the interstitial space freely, thereby also enhancing necrosis. Diffusion-weighted MR imaging depicts differences in diffusion and, ultimately, in membrane integrity between viable and necrotic tumor and may be used to monitor tumor viability during treatment.     

Viral burden and disease progression in HIV-1-infected patients with sickle cell anemia

INTRODUCTION: Magnetic Resonance Imaging (MRI) has been proposed as the diagnostic technique of choice to characterize adrenal tumors. However, the results of the current studies are controversial. MATERIAL AND METHODS: Forty-nine patients with unilateral adrenal masses were submitted to MRI for lesion characterization on the basis of MR signal intensity. Cytology and/or histology demonstrated 14 pheochromocytomas (pheos), 11 adenomas, 3 cysts, 2 myelolipomas, 4 carcinomas, 3 metastases and 1 fibrosarcoma; a clinical diagnosis of adenoma was made in the remaining 11 patients. MR studies were performed using spin-echo (SE) sequences with T1 (TR/TE = 600/17 ms) and T2 (TR/TE = 2000/15-90 ms) weighting. T1-weighted images were also acquired after Gadolinium-DTPA (Gd-DTPA) administration. MR studies were integrated with in- and out-of-phase (TR/TE = 100/4-6 ms) chemical-shift (CS) sequences. MR signal intensity (SI) was analyzed qualitatively and quantitatively; MR results were correlated with tumor type and hormone secretion. RESULTS: The qualitative analysis of T2 images showed high signal intensity in the majority (80%) of adrenal lesions (14 pheos, 12 adenomas, 3 cysts, 2 myelolipomas and 8 malignancies). The quantitative analysis of post-Gd-DTPA T1 images permitted to distinguish adenomas, cysts and myelolipomas from pheos and malignancies. The qualitative analysis of post-Gd-DTPA T2 and T1 images permitted to distinguish pheos and cysts from adenomas and malignancies (p < .05); however, pheos and cysts as well as adenomas and malignancies were not differentiated. MR SI was similar in secreting and nonsecreting adenomas from both a qualitative and a quantitative viewpoints. CS MRI permitted to distinguish adenomas (decreased signal intensity on out-phase relative to in-phase images) from other benign and malignant lesions (no signal change from out-phase to in-phase images). CONCLUSIONS: The qualitative analysis of MR SI on conventional T1 and T2 images does not permit to differentiate adrenal masses. The qualitative evaluation of T1 images after Gd-DTPA administration, the quantitative analysis and CS sequences are technical options improving lesion characterization.     

Effectiveness of slow-release lanreotide, a long-acting somatostatin analogue, in the treatment of acromegaly

We report the use of MRI in the diagnosis, follow-up and therapeutic management of three cases of intralabyrinthine Schwannoma. The diagnosis was based on the history and initial and follow-up MRI findings. The main feature suggesting the diagnosis was a nodular intralabyrinthine mass of low signal intensity on T2-weighted images, and high or isointense signal on T1-weighted images (relative to cerebrospinal fluid), which showed contrast enhancement. Follow-up imaging showed growth of the tumour in one patient. One patient underwent surgery for severe tinnitus. To detect these lesions, MRI should be focussed on the inner ear, using thin-section T2-weighted and T1-weighted images before and after contrast medium. MRI allowed informed surgical planning.     

Hepatic hamartoma in adults. Apropos of a case documented by MRI

A mixed hamartoma of the liver in a 39 year old man is reported. Abdominal ultrasound revealed a 4 cm inhomogeneous echogenic mass with acoustic shadowing. MRI T1 weighted images showed a inhomogeneous low intensity mass with lower gadolinium enhancement than normal liver, a moderate low signal intensity on proton density weighted images, and heterogeneous isosignal intensity on T2 weighted images. Peripheric calcifications were found on pathologic examination.     

Survival of Vibrio spp. including inoculated V. cholerae 0139 during heat-treatment of cockles (Anadara granosa)

Six healthy adult male mongrel dogs underwent cranial cruciate ligament transection in the left stifle. Survey radiography of both stifles and low-field (0.064 T) MRI of the left stifle were performed preoperatively and at 2, 6, and 12 weeks postoperatively. Focal changes in signal intensity were seen with MRI in the subchondral bone of the medial tibial condyle at 2 and 6 weeks postoperatively. At 12 weeks postoperative, a cyst-like lesion was detected using MRI in the subchondral bone of the medial tibial condyle in 4 of 6 dogs and a less defined lesion at this site in the remaining 2 dogs. The cyst-like lesion was spherical in shape and showed typical characteristics of fluid with low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and high signal intensity on inversion recovery images. The lesion was seen in the subchondral bone of the caudal medial and/or middle region of the tibial plateau slightly cranial to the insertion of the caudal cruciate ligament. No subchondral cysts were seen in the tibia on radiographs. Histopathologically, the tibia was characterized by a loose myxomatous phase of early subchondral cyst formation.     

Characterization of 5-HT receptors in rat proximal colon

Gastric leiomyoblastoma is a rare entity. In this report, we describe the magnetic resonance (MR) appearance of a recurrent gastric leiomyoblastoma 14 years after initial presentation. This tumor was heterogeneous and moderately low signal intensity on T1-weighted images and heterogeneous and moderately high signal intensity on T2-weighted images. The tumor also contained foci of low signal intensity on the post gadolinium images, consistent with areas of necrosis. The mass enhanced mildly and increased in enhancement on the delayed images, consistent with a hypovascular mass. Multiple liver metastases were noted. Magnetic resonance findings were confirmed with surgical specimens.     

Leiomyoma of the bladder: report of two cases

We report 2 cases of leiomyoma of the urinary bladder. A 41-year-old female visited our hospital with the complaint of pollakisuria. A solid tumor of the urinary bladder was found by ultrasonography. A large shadow defect at the left-anterior wall was shown by drip infusion pyelography (DIP). Computed tomographic scan (CT) and magnetic resonance imaging (MRI) also revealed a large tumor. T1-weighted image revealed a homogeneous low intensity tumor and T2-weighted image disclosed heterogeneous low intensity tumor. Cystoscopy revealed a large submucosal tumor. Partial cystectomy was performed, and she has had neither recurrence nor metastasis for 36 months. A 32-year-old male was referred to our hospital with the complaint of macrohematuria. A solid tumor of the urinary bladder was found by ultrasonography. A shadow defect was not clearly detected by DIP. A large tumor was detected on the anterior wall by MRI. T1-weighted image showed a homogeneous low intensity tumor and T2-weighted image disclosed a high intensity tumor. Cystoscopy revealed a submucosal tumor on the anterior wall. Urine cytology did not suggest a malignancy. The biopsied specimens revealed only an inflammatory change in the mucosa. Partial cystectomy was carried out. He has had neither recurrence nor metastasis for 29 months. Histological diagnosis in both cases was leiomyoma of the urinary bladder.     

Cervical ecchordosis physaliphora: CT and MR features

We report a case of cervical ecchordosis physaliphora in an elderly man who presented with hemihypoaesthesia and contralateral hemiparesis. MRI showed a well defined, non-enhancing extradural mass lesion on the dorsal surface of the odontoid process of the axis. The lesion was of intermediate signal intensity on T1 weighted images and of low signal intensity on T2 weighted images. CT showed a small bony defect on the adjacent cortex of the odontoid process. Recognition of the imaging features of ecchordosis physaliphora is helpful in suggesting the diagnosis and differentiating the lesion from chordoma.     

Neurologic complications in a case of Werner syndrome

A 39 year old caucasian man was admitted in 1994 to the neurological department with a left pure motor hemiplegia that appeared suddenly. This patient showed typical features of Werner's syndrome. He had a hoarse voice, a diffuse muscle weakness and atrophy in the upper and lower limbs with chronic ulcers on the legs. His scalp and public hair were sparse. Cranial MRI revealed several lesions in the white matter, low signal intensity on T1 weighted images and high signal on T2 weighted images. Cerebrospinal fluid (CSF was inflammatory with hypercytosis and proteinorachia was 0.50 g/l with synthesis of IgG. Sural nerve biopsy revealed muscle atrophy and the loss of myelinated fibers. Thus, central and peripheral nervous systems were affected in this case.     

High signal in the adenohypophysis on T1-weighted images presumably due to manganese deposits in patients on long-term parenteral nutrition

Hypermanganesaemia is reported in patients on long-term parenteral nutrition. Deposition of manganese, giving high signal on T1-weighted images, may involve the basal ganglia. MRI in nine patients (mean age 51 years, range 31-75 years) on long-term parenteral nutrition (mean duration 30 months, range 6-126 months), demonstrated high signal in the anterior pituitary gland on T1-weighted sagittal and coronal images. The gland appeared normal on T2-weighted images. Signal intensity in the basal ganglia on T1-weighted images was increased in all patients. Endocrine assessment showed no significant abnormality. Neurological examination showed a mild parkinsonian movement disorder in one patient. Hypermanganaesemia was present in all nine (1.3-2.8 micromol/l, mean 1.87 micromol/l). The high signal in the anterior pituitary gland was probably related to deposition of paramagnetic substances, especially manganese.     

Mutators and long-term molecular evolution of pathogenic Escherichia coli O157:H7

We report the MRI features and correlative pathologic findings of a lung cancer in a patient with progressive massive fibrosis (PMF). In this case, MRI was able to distinguish the lung cancer as a high signal intensity area, and the fibrotic mass as a low signal intensity area, on both T1-weighted and T2-weighted images when compared with muscle. MRI is potentially useful in distinguishing cancer tissue from PMF in patients with pneumoconiosis.