Renal cell carcinoma: preoperative assessment for enucleative surgery with angiography, CT, and MRI

PURPOSE: Our purpose was to assess various imaging methods in detecting a pseudocapsule of renal cell carcinoma (RCC), which is critical for successful tumor enucleation. METHOD: In 42 patients with histopathologically proven RCC, images obtained at angiography (n = 42), CT (n = 30), and MRI (n = 19) were investigated retrospectively. All patients underwent treatment (enucleation: n = 15; nephrectomy: n = 27). The imaging criteria for the presence of a pseudocapsule were as follows: a surrounding radiolucent rim on angiography, a low or high density rim on CT, and a low intensity rim on MRI. All images were retrospectively reviewed by three radiologists without knowledge of the clinical and histological findings. RESULTS: Thirty-three of 42 RCCs showed a pseudocapsule on the surgical specimen. A pseudocapsule was detected in 67% of tumors (22/33) on angiography, 26% (6/23) on CT, 27% (4/15) on T1-weighted MRI, 93% (14/15) on T2-weighted MRI, 67% (8/12) on dynamic enhanced T1-weighted MRI, and 15% (2/13) on delayed enhanced T1-weighted MRI. CONCLUSION: T2-weighted MR images are superior for visualizing a pseudocapsule of RCC and for providing reliable selection criteria for tumor enucleation.     

High-resolution MRI of pancreatic masses with a new circularly polarized body phased-array coil

A total of 18 patients with clinical suspicion of a pancreatic tumor underwent dynamic contrast-enhanced CT and MRI examinations. A fat-suppressed T1-weighted 2D fast-low-angle-shot (FLASH) sequence and a T2-weighted spin-echo (SE) sequence were applied in a transverse orientation using a circularly polarized (CP) body phased-array coil. The FLASH sequence was repeated after Gd-DTPA administration. The highest spatial resolution was 1.37 x 1.37 x 3.00 mm3. In two cases a half Fourier single-shot turbo-SE sequence (HASTE) was additionally applied. In a comparison between CT and MRI, pancreatic masses could be demonstrated and characterized with excellent image quality. The fat-saturated 2D FLASH sequence yielded the highest contrast-to-noise ratios after Gd-DTPA administration between pancreas and inflammatory or neoplastic lesion. One non-contour deforming carcinoma could be detected only with MRI and was only retrospectively visible on CT with an element of uncertainty. Magnetic resonance imaging using a CP body phased-array coil and fat-suppressed T1- and T2-weighted FLASH, SE, and turbo-SE sequences offers diagnostic possibilities in improved imaging of the pancreas.     

Autoimmune pancreatitis: CT and MR characteristics

OBJECTIVE: Our goal was to elucidate the CT and MR imaging characteristics in patients with autoimmune pancreatitis, which is a reversible chronic pancreatitis with an autoimmune cause. CONCLUSION: On CT and MR imaging, a capsulelike rim, which is thought to correspond to an inflammatory process involving peripancreatic tissues, appears to be a characteristic finding of autoimmune pancreatitis. Also, diffuse pancreatic enlargement along with hypointensity on T1-weighted MR images and delayed enhancement on dynamic CT and MR studies are other features of this disorder.     

Congenital ganglioglioma: report of a case with an unusual imaging appearance

A newborn presented with a cerebral ganglioglioma. This is a rare diagnosis in a neonate. The imaging appearance (hyperdense on CT, hyperintense on T1-weighted and hypointense on T2-weighted MRI) is very unusual for this type of tumor.     

Petrous apex arachnoid cyst: radiographic confusion with primary cholesteatoma

The advent of combined computed tomography (CT) and magnetic resonance imaging (MRI) for the evaluation of petrous apex lesions has improved the otologist's ability to differentiate among many disease processes. Temporal bone CT details osseous anatomy, whereas MRI delineates soft tissue signal characteristics. The employment of these two imaging modalities is often successful in differentiating between cholesterol common entities encountered in the petrous apex. The finding of a smoothly marginated, expansile, bone eroding lesion on CT, coupled with hypointensity on T1-weighted and hyperintensity on T2-weighted images on MRI, is highly suggestive of cholesteatoma. The authors recently encountered two cases of arachnoid cyst involving the petrous apex that shared the same imaging features seen with the more common cholesteatoma. One patient presented with tic douloureux, whereas the other had a spontaneous transotic cerebrospinal fluid leak. The contemporary skull base surgeon should include arachnoid cyst as a rare possibility in the evaluation and treatment of petrous apex lesions.     

Cognitive dysfunction and impaired organization of complex motility in degenerative parkinsonian syndromes

PURPOSE: Our purpose was to present imaging findings of six cases proven or supposed to be von Meyenburg complexes (VMCs) with a basis of reviewing the pathologic literature and to describe imaging points for the diagnosis of typical VMC along with its differential diagnosis. METHOD: Six cases were diagnosed as VMC of the liver with imaging modalities (one had histopathologic proof). Both ultrasound (US) and CT were available for all cases, and MRI was used for three cases. Follow-up with US, CT and/or MRI was performed in five cases. RESULTS: US detected varying abnormalities of the livers in four cases. CT and MRI revealed multiple or numerous intrahepatic tiny (usually < 5 mm) cystoid lesions in all of the cases. The lesions were scattered throughout the livers, and some of them were located more frequently adjacent to the medium-sized portal veins than to the hepatic veins of similar size on CT. Moreover, some lesions were apparently located in the subcapsular areas (up to the hepatic capsules). They were usually irregular in shape and showed no enhancement but increased in number by approximately 80-150% after administration of intravenous contrast medium. The T2-weighted MR images and MR cholangiopancreatography showed the lesions to be much more apparent and to be more numerous than T1-weighted images did. Follow-up of five cases with imaging modalities did not show remarkable change of the lesions. CONCLUSION: Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.     

Gadolinium enhancement: improved MRI detection of retinoblastoma extension into the optic nerve

We performed T1-, T2-, proton density-weighted, and T1-weighted gadolinium-enhanced MRI on 24 patients with retinoblastoma, using a 1.5 T superconducting unit and head and orbital surface coil imaging. All patients underwent a complete ophthalmologic examination, including B-scan ultrasonography. CT was performed on 10 of 24 patients. Pathologic correlation was obtained in 18 patients who required enucleation. Contrast-enhanced T1-weighted MRI with fat suppression was the sequence most sensitive to optic nerve extension and provided the greatest differentiation between tumor and uninvolved extrascleral tissue. Retinoblastoma demonstrated contrast enhancement.     

The clinical utility of magnetic resonance imaging in 3-dimensional treatment planning of brain neoplasms

Results of the clinical experience gained since 1986 in the treatment planning of patients with brain neoplasms through integration of magnetic resonance imaging (MRI) into computerized tomography (CT)-based, three-dimensional treatment planning are presented. Data from MRI can now be fully registered with CT data using appropriate three-dimensional coordinate transformations allowing: (a) display of MRI defined structures on CT images; (b) treatment planning of composite CT-MRI volumes; (c) dose display on either CT or MRI images. Treatment planning with non-coplanar beam arrangements is also facilitated by MRI because of direct acquisition of information in multiple, orthogonal planes. The advantages of this integration of information are especially evident in certain situations, for example, low grade astrocytomas with indistinct CT margins, tumors with margins obscured by bone artifact on CT scan. Target definitions have repeatedly been altered based on MRI detected abnormalities not visualized on CT scans. Regions of gadolinium enhancement on MRI T1-weighted scans can be compared to the contrast-enhancing CT tumor volumes, while abnormalities detected on MRI T2-weighted scans are the counterpart of CT-defined edema. Generally, MRI markedly increased the apparent macroscopic tumor volume from that seen on contrast-CT alone. However, CT tumor information was also necessary as it defined abnormalities not always perceptible with MRI (on average, 19% of composite CT-MRI volume seen on CT only). In all, the integration of MRI data with CT information has been found to be practical, and often necessary, for the three-dimensional treatment of brain neoplasms.     

Fetal intracranial hemorrhage. Imaging by ultrasound and magnetic resonance imaging

OBJECTIVE: To describe the magnetic resonance imaging (MRI) findings associated with fetal intracranial hemorrhage and to compare them with ultrasound findings. STUDY DESIGN: In four pregnancies complicated by fetal intracranial hemorrhage, fetal imaging was carried out using T2-weighted fast spin echo sequences and T1-weighted fast low angle shot imaging sequences and by transabdominal ultrasonography. RESULTS: An antepartum diagnosis of hemorrhage was made by ultrasound in one case and by MRI in two. Retrospectively, the hemorrhagic area could be identified from the MRI images in an additional two cases and from the ultrasound images in one case. In the cases of intraventricular hemorrhage, the MRI signal intensity in the T1-weighted images was increased in the hemorrhagic area as compared to the contralateral ventricle and brain parenchyma. In a case with subdural hemorrhage, T2-weighted MRI signals from the hemorrhagic area changed from low-to high-intensity signals during four weeks of follow-up. Better imaging of the intracranial anatomy was possible by MRI than by transabdominal ultrasonography. CONCLUSION: MRI can be used for imaging and dating fetal intracranial hemorrhages. Variable ultrasound and MRI findings are associated with this complication, depending on the age and location of the hemorrhage.     

MRI findings in cerebral fat embolism

The purpose of this retrospective study was to demonstrate the MRI features of cerebral manifestations in patients with fat embolism syndromes in comparison with cerebral CT (CCT). Magnetic resonance imaging was performed according to standard protocols revealing multiple small non-confluent hyperintense intracerebral lesions larger than 2 mm on proton-density and T2-weighted images to various extents in three of four patients with clinically suspected cerebral fat embolism. Cerebral CT was negative in all patients. Our findings confirm that MRI can detect cerebral fat embolism with a higher sensitivity than CCT. Thus, MRI should be the first choice for imaging of cerebral fat embolism.     

Circadian-time rhythm of hepatic protein kinase C of rats pretreated with phenobarbital

The magnetic resonance imaging (MRI) differential diagnosis of intrahepatic biloma from intrahepatic subacute hematoma has been reported in two cases. The biloma was heterogenously intense on T1-weighted images and homogenously hyperintense on T2-weighted images. The hematoma was hyperintense on the both T1- and T2-weighted MR images. The clinical significance of this MRI difference is that intrahepatic biloma needs drainage, whereas intrahepatic hematoma can heal spontaneously.     

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.     

Radiological diagnosis of viral encephalitis

Most of viral encephalitis may demonstrate no specific change on CT and MR images. Brain swelling, edema, abnormal density (CT) and abnormal intensity (MR) can be detected in herpes simplex encephalitis and enterovirus encephalitis (coxsackie, echo, polio). The common finding on CT and MRI in patients with HIV encephalopathy are atrophy, leukomalacia. Progressive multifocal leukoencephalopathy (PML) shows multifocal oval or round white matter T2-hyperintensities on MR images. Subacute sclerosing panencephalitis (SSPE) may present slight changes in the subcortical and periventricular white matter, as well as basal ganglia. Progressive disorder makes widespread T1-low, T2-high intensity area and atrophy. MRI of acute disseminated encephalomyelitis (ADEM) shows multifocal subcortical hyper intense foci on T2-weighted studies. The deep white matter, brainstem, thalamus and cerebellum can be affected. Most of ADEM lesions resolve. Imaging findings of acute lymphocytic meningitis by echovirus and coxsackievirus are usually normal.     

Relation between MR abnormalities and patterns of cognitive impairment in multiple sclerosis

OBJECTIVE: This study correlated the extent of abnormalities detected by different magnetic resonance imaging (MRI) techniques [proton density (PD)-weighted, T1-weighted, and magnetization transfer imaging (MTI)] with the overall cognitive, frontal lobe, and memory impairments in patients with MS. PATIENTS: There were 30 clinically definite MS patients, with different disease courses. Exclusion criteria: psychoactive/steroid treatments, mood disorders, acute relapse phase. MAIN OUTCOME MEASURES: Neuropsychological test results. Total (TLL) and frontal (FLL) lesion loads assessed from PD-weighted, T1-weighted (22 patients), and MTI (22 patients) MRI scans. Average lesion MT ratios (MTR) and analysis of the MTR histograms from brain tissue axial slabs on MTI scans. RESULTS: Patients with frontal lobe deficits (n=15) or memory impairment (n-17) had a higher TLL on PD scans (p=0.04 and p=0.01, respectively). Patients with frontal lobe deficits had higher FLL on PD scans (p=0.01) and TLL on MTI (p=0.03) scans. No significant relationships between the extent of T1-weighted lesion loads and the presence of any neuropsychological impairment. Mean MTR of both MS lesions and whole brain tissue was lower in patients with frontal lobe impairment (p=0.04). MRI lesion loads correlated significantly with some neuropsychological test scores. CONCLUSIONS: Lesion loads on PD-weighted MRI and MTI-derived measures are associated with cognitive decline in MS patients. Overall macroscopic and microscopic brain damage is more important than the corresponding regional brain disease in determining deficits of selective cognitive domains.     

MR appearance of parasymphseal insufficiency fractures of the os pubis

OBJECTIVE: To clarify the MRI features of parasymphyseal insufficiency fractures of the os pubis. DESIGN AND PATIENTS: MRI was performed in four postmenopausal women with parasymphyseal insufficiency fractures. The diagnosis was confirmed with plain films in every patient. T1-weighted and T2-weighted images were obtained in four patients using a 1.5-T unit. Postcontrast T1-weighted imaging was also done in three patients. RESULTS AND CONCLUSIONS: MRI of pubic parasymphyseal insufficiency fracture characteristically demonstrates a hyperintense mass lesion with a hypointense rim on T2-weighted imaging, showing peripheral and septal enhancement after contrast administration. It is important to have this entity in mind in patients with osteoporosis, especially in patients with a history of pelvic irradiation for malignant disease, so as not to misinterpret it as a chondroid tumor or bone metastasis.     

Use of fluorescent in situ hybridization to detect aneuploidy in cervical dysplasia

An 8 year old girl with acute disseminated encephalomyelitis (ADEM) is described. Elevated serum antibody titers suggested recent Mycoplasma pneumoniae infection. T2-weighted image of magnetic resonance imaging (MRI) disclosed multiple lesions of high signal intensity in bilateral basal ganglia and thalami as well as in the white matter. Postcontrast T1-weighted image revealed an enhanced lesion in the deep white matter. She showed rapid clinical improvement in response to corticosteroid therapy. The lesions had disappeared completely on MRI performed 10 weeks after the onset. ADEM is believed to be a demyelinating disorder of probable autoimmune etiology. MRI findings in this case may support the hypothesis that the primary pathological event is vascular injury and demyelination occurs only as a secondary phenomenon.     

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.     

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.     

MRI and MR angiography of vertebral artery dissection

A review of 4,500 angiograms yielded 11 patients with dissection of the vertebral arteries who had MRI and (in 4 patients) MR angiography (MRA) in the acute phase of stroke. One patient with incidental discovery at arteriography of asymptomatic vertebral artery dissection and two patients with acute strokes with MRI and MRA findings consistent with vertebral artery dissection were included. Dissection occurred after neck trauma or chiropractic manipulation in 4 patients and was spontaneous in 10. Dissection involved the extracranial vertebral artery in 9 patients, the extra-intracranial junction in 1, and the intracranial artery in 4. MRI demonstrated infarcts in the brain stem, cerebellum, thalamus or temporo-occipital regions in 7 patients with extra- or extra-intracranial dissections and a solitary lateral medullary infarct in 4 patients (3 with intracranial and 1 with extra-intracranial dissection). In 2 patients no brain abnormality related to vertebral artery dissection was found and in one MRI did not show subarachnoid haemorrhage revealed by CT. Intramural dissecting haematoma appeared as crescentic or rounded high signal on T1-weighted images in 10 patients examined 3-20 days after the onset of symptoms. The abnormal vessel stood out in the low signal cerebrospinal fluid in intracranial dissections, whereas it was more difficult to detect in extracranial dissections because of the intermediate-to-high signal of the normal perivascular structures and slow flow proximal and distal to the dissection. In two patients examined within 36 h of the onset, mural thickening was of intermediate signal intensity on T1-weighted images and high signal on spin-density and T2-weighted images. MRA showed abrupt stenosis in 2 patients and disappearance of flow signal at and distal to the dissection in 5. Follow-up arteriography, MRI or MRA showed findings consistent with occlusion of the dissected vessel in 6 of 8 patients.