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J M Prager

Publications and source records attributed to J M Prager.

8 recordsLinked to original sources
PubMed2000

Serial CT and MR imaging of carmustine wafers.

BACKGROUND AND PURPOSE: A new option in the treatment of recurrent malignant glioma is surgical placement of chemotherapy-laden biodegradable wafers. We describe the CT and MR appearance of chemotherapy wafers in patients after surgery for recurrent malignant glioma METHODS: Eighteen patients had carmustine (BCNU) wafers implanted during reoperation for malignant glioma; three patients had empty, placebo wafers placed. The 21 patients had a total of 22 CT and 57 MR imaging studies. Repeat CT studies were conducted for up to 6 months, the MR studies for up to 1 year. Examinations were evaluated for attenuation on CT scans, signal abnormalities on MR images, and changing appearance during the follow-up period. Enhancement characteristics were also assessed. RESULTS: On CT scans, 13 of 16 acute (<7 days) cases showed linear high-attenuation wafers, with three showing low attenuation. On MR images, all T1 and T2 studies performed in the acute stage showed decreased signal of the wafers. Eight of 15 studies showed a transient increase in T1 only at about 2 months. Wafers decreased in conspicuity on both CT and MR studies after 2 months. The wafers did not enhance. One postoperative tumor showed a transient increase in edema and increased enhancement at 5 weeks. The presence or absence of BCNU within the wafers did not change their appearance. CONCLUSION: BCNU wafers have a characteristic appearance: in the first 7 days after implantation they are linear, usually of increased attenuation on CT scans, and always show decreased signal on MR images; they do not enhance, and become less conspicuous after 2 months.

Antineoplastic Agents, Alkylating↗
PubMed1996

Spinal headaches after myelograms: comparison of needle types.

OBJECTIVE: We compared traditional bevel-tip end-hole spinal needles and pencil-point-tip side-hole needles for the incidence, severity, and duration of spinal headaches in subjects who had myelograms. Age, sex, and myelographic findings were examined. SUBJECTS AND METHODS: We studied 138 subjects referred for myelograms. For 108 procedures, we randomly used 22-gauge Quinke bevel-tip end-hole needles or 22-gauge Sprotte pencil-point-tip needles. The 30 additional subjects were examined with Gertie Marx pencil-point-tip needles. All myelograms were performed by one of two neuroradiologists using recommended doses of iohexol. The myelograms were examined by an independent neuroradiologist for quality of image and presence of extraarachnoid contrast material. Five to 14 days after myelography, subjects were telephoned by an independent observer and asked about the presence, severity, duration, and positional quality of headache. Spinal headache is defined by positional quality and increases in severity when the subject moves from horizontal to sitting or standing. RESULTS: We found that four (8%) of 52 subjects who had myelograms with Sprotte needles had spinal headaches. Likewise, 14 (25%) of 56 subjects who had myelograms with Quinke needles had spinal headaches. We calculated a statistically significant difference in the incidence of spinal headaches using chi-square analysis (p = .02). The average grade and duration of the spinal headaches did not differ significantly, although they were less marked in the Sprotte group. Spinal headaches occurred more frequently in young and middle-aged subjects than in older subjects. We found one definite extraarachnoid injection in each group. For the Gertie Marx needles, two (7%) of 30 subjects had spinal headaches. The average grade of postmyelogram headache was 2.5, and the mean duration was 1 day. There were no mixed injections. CONCLUSION: We found a significant reduction in spinal headaches after myelograms when we used the pencil-point-tip side-hole needle. These results support the routine use of these needles for myelography in young and middle-aged patients.

Adult↗
PubMed1994

The magnetization transfer effect in cerebral infarction.

PURPOSE: To estimate the age of cerebral infarcts using magnetization transfer. METHODS: Twelve patients with radiographically and clinically documented cortical and subcortical cerebral infarctions underwent MR imaging on a 0.1T magnet. Magnetization transfer contrast images were generated by application of off-resonance pulses to every other repetition time on intermediate-weighted images. The magnetization transfer effect was calculated by obtaining an intensity value in the region of interest within the infarcted area. RESULTS: The data show a pattern in which the magnetization transfer effect decreases as the chronicity of the infarct increases. Infarcts less than 1 week old had an average magnetization transfer effect of 0.35. Those more than 1 week and less than 1 month old average 0.30. Infarcts more than 1 month and specifically those more than 1 year old averaged 0.16 or less. CONCLUSION: Magnetization transfer offers the potential to estimate the age of cerebral infarcts.

Acute Disease↗
PubMed1994

Magnetization transfer: a potential method to determine the age of multiple sclerosis lesions.

PURPOSE: To determine whether magnetization transfer contrast can differentiate acute from chronic lesions in multiple sclerosis. METHODS: Thirteen patients with multiple sclerosis and eight healthy patients were studied with MR using a 0.1-T system. Relatively T2-weighted spin-echo images were obtained without and with magnetization transfer contrast. The magnetization transfer effect of multiple sclerosis lesions was calculated and compared with the ages of the lesions. The magnetization transfer effect of normal-appearing white matter in patients with multiple sclerosis was calculated and compared with the magnetization transfer effect of white matter in healthy volunteers. Statistical analysis was performed. RESULTS: White matter in the healthy volunteers had values from 0.40 to 0.45. Normal-appearing white matter in the patients with multiple sclerosis had magnetization transfer effect values ranging from 0.41 to 0.45. Multiple sclerosis plaques of less than 1 year's duration had magnetization transfer effect values ranging from 0.05 to 0.26; older plaques had values from 0.25 to 0.41. The difference in the distributions of these values for acute and chronic multiple sclerosis plaques is statistically significant. CONCLUSION: Current imaging modalities do not differentiate acute multiple sclerosis lesions from chronic ones. Our data on magnetization transfer show a statistically significant difference in magnetization transfer effect values between lesions of less than 1 year's duration and older lesions. The different values may correspond to the histologic changes of multiple sclerosis plaques over time. Magnetization transfer may be a reliable method for determining the age of multiple sclerosis lesions.

Acute Disease↗
PubMed1991

The radiology of headache.

The patient who presents with a severe and acute headache should be evaluated radiographically with CT. The key diagnosis to make in this situation is hemorrhage, either subarachnoid or intraparenchymal. Computed tomography is more sensitive to acute hemorrhage than is MRI. When the patient is stable, MRI frequently contributes information to narrow the diagnostic possibilities, because vascular malformations and certain parenchymal lesions have a characteristic appearance on MRI. Hydrocephalus may also present acutely and is easily seen on CT or MRI. In a patient may show WMF and atrophy. The patient with trigeminal neuropathy may demonstrate central or peripheral lesions. In temporomandibular joint dysfunction, conventional tomography and MRI are frequently used. Magnetic resonance imaging shows excellent detail of the disk and surrounding soft tissues, whereas tomography better demonstrates bony changes. When a history of trauma is present, MRI may show a subacute subdural hematoma. These collections are easily seen on MRI, even when isodense on CT. Evidence of old shear injury is also well seen on MRI. Finally, neoplastic, inflammatory, congenital, and idiopathic sources of headache may be demonstrated by either MRI or CT, depending on presentation. MRI will generally show superior characterization.

Adult↗
PubMedDate not supplied

High-b-value diffusion-weighted MR imaging of suspected brain infarction.

BACKGROUND AND PURPOSE: Recent technological advances in MR instrumentation allow acquisition of whole-brain diffusion-weighted MR scans to be obtained with b values greater than 1,000. Our purpose was to determine whether high-b-value diffusion-weighted MR imaging improved contrast and detection of signal changes in acute and chronic brain infarction. METHODS: We prospectively evaluated the MR scans of 30 subjects with a history of possible brain infarction on a 1.5-T MR imager with 40 mT/meter gradients (slew rate 150 T/m/s) by use of the following single-shot echo-planar diffusion-weighted MR sequences: 1) 7,999/ 71.4/1 (TR/TE/excitations, b = 1,000; 2) 999/ 88.1/3, b = 2,500; and 3) 7,999/ 92.1/4, b = 3,000. Diffusion-weighted MR imaging was performed in three orthogonal directions during all sequences. All subjects were scanned with fast fluid-attenuated inversion recovery (FLAIR) (10,006/145/2,200/1 [TR/TE/TI/excitations]) and fast spin-echo T2-weighted (3,650/95/3 [TR/TE/excitations], echo train length, 8). The diagnosis of brain infarction was established by clinical criteria. RESULTS: Twenty women and 10 men with a mean age of 67.7 years were enrolled in the study. One subject was excluded owing to poor image quality. Twelve of 29 subjects had a clinical diagnosis of acute infarction. All 12 had lesions that were hyperintense on diffusion-weighted images at all three b values; five were cortical and seven subcortical. There was increased contrast of all lesions on high-b-value scans (b = 2,500 and 3,000). Lesions that were hypointense on diffusion-weighted images were identified and evaluated at the three different b values. At b = 1,000, there were 19 hypointense lesions, whereas at b = 2,500 and 3,000 there were 48 and 55 lesions, respectively. On FLAIR and T2-weighted images, these low-signal lesions were predominantly chronic, subcortical, ischemic lesions and lacunar infarcts, but four chronic cortical infarcts, one porencephalic cyst, and one primary brain tumor were also found. Low-signal lesions were also noted to have increased contrast on high-b-value diffusion-weighted scans. CONCLUSION: High-b-value diffusion-weighted MR imaging (b = 2,500 or b = 3,000) had no impact on diagnosis of acute infarction. High-b-value diffusion-weighted MR imaging (b = 2,500) combined with diffusion-weighted MR imaging at b = 1,000 improves tissue characterization by increasing the spectrum of observed imaging abnormalities in patients with suspected brain infarction.

Aged↗