Biomedical subjects

R Lorig

Publications and source records attributed to R Lorig.

10 recordsLinked to original sources

PubMed1994

Magnetic resonance imaging of pelvic tumors in children.

Pelvic tumors in children may be large, complex and of unknown origin. Preoperative radiological information regarding tumor localization and extent becomes essential in these cases for proper staging and surgical planning. Magnetic resonance imaging (MRI) offers the ability to enhance the surgical preparation of children who present with a pelvic mass. Advantages of MRI over computerized tomography include improved soft tissue characterization, signal enhancement of neuroendocrine tumors and multiplanar imaging. These features better define the origin, size and extent of tumors. In addition, no ionizing radiation is required. Several examples of pelvic tumors are presented. The new anatomical information provided by MRI altered surgical planning previously based on computerized tomography findings alone.

Adolescent↗

PubMed1991

Magnetic resonance imaging of cutaneous neoplasms: clinicopathologic correlation.

Recently, magnetic resonance imaging (MRI) has been reported to be clinically useful, in selected cases, in patients with melanocytic skin lesions. This report describes good resolution, clinically useful MRI scans of squamous cell carcinoma, dermatofibroma, and primary cutaneous B-cell lymphoma. The tumor depth measured by MRI was in excellent correlation with Breslow's depth measurements, indicating that MRI is probably the radiologic technique of choice for preoperative evaluation of the extent and depth of primary and recurrent skin tumors. This report also provides the authors' recommendations for obtaining optimal MRI images of cutaneous lesions.

Adult↗

PubMed1990

Magnetic resonance imaging for assessment of vena caval tumor thrombi: a comparative study with venacavography and computerized tomography scanning.

We assessed the accuracy of magnetic resonance imaging in demonstrating the presence and extent of vena caval tumor thrombi. The study group included 20 patients with vena caval thrombi from renal cell carcinoma (18), renal pelvic transitional cell carcinoma (1) and adrenal pheochromocytoma (1). Preoperative diagnostic studies included magnetic resonance imaging in all patients, inferior venacavography in 16 and computerized tomography scanning in 15. All patients underwent an operation in which the presence and extent of the vena caval thrombus were confirmed. Magnetic resonance imaging accurately delineated the presence and extent of the thrombus in all 20 patients (100%). Venacavography was accurate in 15 patients (94%) but 8 (50%) required a retrograde and antegrade study. Computerized tomography scanning demonstrated the presence of a tumor thrombus in all 15 patients but accurately delineated the cephalad extent of the thrombus in only 5 (33%). In patients with vena caval tumor thrombi magnetic resonance imaging can provide accurate information regarding the extent of vena caval involvement while avoiding the need for an invasive contrast imaging study.

Adrenal Gland Neoplasms↗

PubMed1990

Right renal mass with vena caval thrombus.

This case illustrates the difficulties that sometimes occur in the evaluation of patients with a nonfunctioning kidney. Because of the clinical presentation, suggestive of renal cell carcinoma, no urinary cytology study was obtained from the affected kidney. This study certainly would have led to the correct diagnosis. Despite this fact, the operative management would not have changed except for complete removal of the ureter. In our case we elected to follow the distal ureter by ureteral washings and ureteroscopy during follow-up cystoscopy studies to preclude a further operation. Although no data are available on the role of adjuvant therapy in these patients, because of the poor prognosis associated with such extensive disease we gave our patient 2 courses of M-VAC in an attempt to prevent progression of the disease.

Aged↗

PubMed1989

Magnetic resonance imaging of cutaneous melanocytic lesions.

This is the first literature report on magnetic resonance imaging (MRI) examination of cutaneous melanocytic or any other type of skin lesions. Good resolution, clinically useful MRI scans of a congenital nevus and a metastatic melanoma to the skin are presented. The potential usefulness of MRI technique to physicians dealing with cutaneous disease is discussed.

Adult↗

PubMed1989

Adrenal imaging. Computed tomographic scanning and magnetic resonance imaging.

On the basis of this review and others, adrenal imaging using MRI requires functional biochemical data, such as scintigraphy (NP-59 and MIBG), for cortical adrenal assessment. For medullary hyperfunction such as intra-adrenal pheochromocytomas and neuroblastomas, MRI provides excellent staging and localization. Computed tomography is preferred for biochemically established hyperfunction such as Cushing's and Conn's syndromes.

Adrenal Gland Diseases↗

PubMed1988

The role of magnetic resonance imaging in the staging of bladder carcinoma.

The clinical staging of bladder carcinoma traditionally has relied on transurethral resection of the bladder tumor, urinary cytology, excretory urography and an examination with the patient under anesthesia. Recent evidence has shown magnetic resonance imaging to be effective in the staging of bladder cancer. Whether magnetic resonance imaging is more accurate than conventional clinical staging techniques has not been answered. To determine the usefulness of magnetic resonance imaging in this regard 34 patients with bladder carcinoma underwent staging by this technique before radical cystectomy. The magnetic resonance imaging stage and conventional clinical stage were compared to the final pathological stage. Magnetic resonance imaging had an over-all accuracy of 50 per cent versus 57 per cent for conventional staging techniques and it identified 2 of 5 patients with nodal disease. To date magnetic resonance imaging does not appear to be better than conventional clinical staging techniques in patients with bladder carcinoma.

Carcinoma in Situ↗

PubMed1988

The association of neuroblastoma with myoclonic encephalopathy of infants: the use of magnetic resonance as an imaging modality.

The association of neural crest tumors with myoclonic encephalopathy of infants has been well described. Since these tumors often are clinically occult the diagnostic modalities used to identify these lesions need to be sensitive. We describe a child with neuroblastoma associated with infantile myoclonic encephalopathy in whom magnetic resonance imaging identified the lesion while other techniques were unable to demonstrate a mass clearly. Magnetic resonance imaging should be considered as a diagnostic modality when adrenal lesions are suspected but not apparent with other imaging techniques.

Adrenal Gland Neoplasms↗

PubMed1988

Evolving focal cerebral ischemia in cats: spatial correlation of nuclear magnetic resonance imaging, cerebral blood flow, tetrazolium staining, and histopathology.

The spatial correlation of nuclear magnetic resonance imaging (NMRI) and cerebral blood flow (CBF) may improve our ability to identify ischemic brain lesions and may provide further insight into the pathophysiology of early cerebral ischemia. Eleven pentobarbital-anesthetized adult cats underwent exposure of the common carotid arteries bilaterally and the right middle cerebral artery through a transorbital approach. Baseline NMRI images were obtained with a single spin-echo, multislice technique using a 0.6-T field, 0.4-cm slice thickness, and a surface coil. Focal ischemia was produced with right middle cerebral artery occlusion and potentiated with bilateral common carotid artery ligation. Sequential NMRI studies were then performed at 1, 2, 4, 6, and 12 hours or until CBF was determined in the same cats using [14C]iodoantipyrine at either 2 (n = 2), 4 (n = 2), 6 (n = 2), or 12 (n = 1) hours after the time of occlusion. This protocol allowed temporal and spatial correlation of NMRI and CBF. Alternate 5-mm brain slices were incubated with 1% 2,3,5-triphenyltetrazolium chloride (TTC) for 45 minutes at 37-41 degrees C and frozen in liquid Freon for later autoradiographic CBF determination. Four cats were studied only with NMRI and TTC (not CBF). The correlation between areas of increased NMRI signal intensity observed in T2-weighted images (repetition time 2,000 msec, echo time 120 msec), vital staining with TTC, low CBF, and routine histology was evaluated. During the early phase (less than 6 hours), T2-weighted NMRI changes were localized to the central ischemic gray matter areas, as defined in the later CBF images, with no involvement of the white matter. By the twelfth hour the NMRI changes involved the entire ischemic area including gray and white matter. The initial visible changes seen on T2-weighted NMRI are suggestive of cellular edema, and the later changes are characteristic of vasogenic edema. The spread of NMRI changes compared with the ischemic area determined from autoradiographic CBF is consistent with the previously described biphasic evolution of ischemic injury. These data suggest that T2-weighted NMRI could be used clinically to delineate areas of acute ischemic stroke.

Animals↗

PubMedDate not supplied

Cranial postoperative site: MR imaging appearance.

The ability to diagnose adverse postcraniotomy or postcraniectomy events is essential for proper postoperative care. The importance of identifying postoperative changes on CT has previously been shown. The purpose of this study is to assess the normal and abnormal MR changes that may be seen in the postcraniotomy/postcraniectomy period. The postoperative MR, CT, and medical records of 41 postcraniotomy patients and 26 postcraniectomy patients were reviewed. Reasons for choosing craniectomy over craniotomy included decompression, infected flap, bony involvement by tumor, and posttraumatic skull. In general, the postoperative normal anatomy was better seen with MR. Postoperative events included hemorrhage (two), infection (five), cyst formation (10), and recurrent tumor (five). In general, MR was found to be more useful than CT for the detection of hemorrhage and infection after craniotomy or craniectomy and for the proper localization of postoperative cysts. MR proved to be a useful method for following postoperative sites in the skull.

Craniotomy↗