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Biomedical subjects

C R Jack

Publications and source records attributed to C R Jack.

At least 127 records · Page 7Linked to original sources
PubMed1988

Cerebrospinal fluid-iophendylate contrast on gradient-echo MR images.

The effect on the signal intensities of cerebrospinal fluid (CSF) and iophendylate (Pantopaque) and on CSF-iophendylate contrast was studied in vitro with a small-nutation-angle (alpha) gradient refocused magnetic resonance (MR) imaging technique (GRASS) as alpha, repetition time (TR), and echo time (TE) were varied. CSF signal intensity was consistently greater than that of iophendylate. Therefore, retained intraspinal iophendylate may be considered in the differential diagnosis of focal areas of low signal intensity at the periphery of the spinal canal on GRASS images. At constant TE and TR, an increase in alpha from 6 degrees to 45 degrees increased the signal intensities of CSF and iophendylate but decreased CSF-iophendylate contrast. At constant alpha and TR, an increase in TE from 13 to 28 msec decreased the signal intensities of CSF and iophendylate but increased contrast. At constant alpha and TE, an increase in TR from 50 to 400 msec increased the signal intensities of CSF and iophendylate, as well as contrast. Clinical examples of the contrast behavior of retained intraspinal iophendylate on both spin-echo and GRASS images corroborate the experimental findings. Retained intraspinal iophendylate may mimic the appearance of intra-or extra-dural lesions, magnetic susceptibility artifact, and flow on gradient-echo MR images of the spine.

Cerebrospinal Fluid↗
PubMed1988

Superficial temporal-middle cerebral artery bypass: clinical pre- and postoperative angiographic correlation.

Between 1974 and 1982, an anastomosis between a pedicle of the superficial temporal artery (STA) and a cortical branch of the middle cerebral artery (MCA) was performed in 163 carotid systems in 157 patients for internal carotid artery occlusion in whom postoperative angiograms were available for analysis. The angiographic opacification of the arterial system was correlated with the patient's preoperative neurological function and stroke in the follow-up period. From this analysis, the following observations were made: 1) 96% of bypasses were patent; 2) 80% of bypasses achieved a high or medium MCA filling score; 3) there was hypertrophy of the STA in 70% of the cases; 4) greater bypass filling occurred in hemispheres with nonvisualized preoperative collateral circulation than in those with readily visualized collateral flow; 5) a meaningful correlation between angiographically assessed postoperative bypass function and stroke rate was not possible because only four patients suffered an ipsilateral hemispheric stroke in the 8-year follow-up period; and 6) patients who were neurologically unstable before the procedure were at greatest risk for a stroke in the follow-up period. It is apparent that objective analysis of the effectiveness of an STA-MCA bypass, or any other form of extracranial bypass, must await the development of new diagnostic studies in which high-resolution three-dimensional quantification of cerebral blood flow is possible. These studies will necessarily be correlated with preoperative and follow-up clinical data.

Adult↗
PubMed1986

Radiologic evaluation of extracranial to Sylvian middle cerebral artery bypass.

At this institution a new procedure has been developed that involves anastomosing one of the branches of the superficial temporal artery to one of the major trunks of the middle cerebral artery in the Sylvian fissure. This procedure has been performed in 22 cases to date. Clinical indications for this procedure have fallen into four major categories. This new type of anastomosis produces greater bypass flow than conventional cortical middle cerebral artery anastomoses, and may be a better therapeutic alternative in certain clinical situations. The preoperative and postoperative angiographic evaluation of these patients is discussed. The radiologic results in this series of patients are reviewed.

Adult↗
PubMed1986

Ultrasonic features of two cases of spinal cord hemangioblastoma.

Two patients with proven intramedullary spinal cord hemangioblastomas were examined with intraoperative ultrasound. The ultrasonic features of a hyperechoic intramedullary mass accompanied by nearby cysts and, in one case, by a syrinx correspond with well-known pathological and computed tomographic descriptions of these tumors. Ultrasonic guidance enabled the surgeon to identify the exact location of the tumors and to proceed with the surgery, limiting the dissection to the area detected. The ultrasound also revealed cysts associated with the tumors, thus providing valuable information to guide the progress of surgery.

Adolescent↗
PubMed1986

Radiolabeled polyvinyl alcohol particles: a potential agent to monitor embolization procedures.

Polyvinyl alcohol sponge (PVA) is a widely used angiographic embolic agent. The radiolabeling of PVA can accurately identify particle localization and may decrease the possibility of patient morbidity from embolization to distal sites. We incorporated 99mTc sulfur colloid (SC) into PVA by heating. Animal experiments demonstrated the in vivo stability of the 99mTc SC-PVA complex and the efficacy of external imaging. 99mTc SC-PVA biodistribution data and external NaI(T1) scintillation probe counts were performed, to assess anatomic localization. Embolization with this complex was performed in a patient.

Angiography↗
PubMed1986

Therapeutic embolization angiography for extra-axial lesions in the head.

Percutaneous transcatheter arterial embolization has played an increasingly important role in the management of vascular lesions in the head. Embolization can promote thrombosis within vascular tumors and malformations, reduce bleeding and decrease the need for transfusion intraoperatively, and facilitate surgical approaches to otherwise unresectable lesions. It is important for the clinician to be aware of this interventional technique because many of the patients who are considered for embolization are triaged through several different clinical areas, and much can be gained from the collaboration of the clinician, the surgeon, and the angiographer. We performed 31 therapeutic particulate embolization procedures for extra-axial head lesions in 23 patients by using flow-directed techniques. Of these procedures, 11 resulted in vascular occlusion and 15 resulted in 80 to 95% obstruction, as demonstrated by angiography. In 14 patients, embolization was performed preoperatively both to decrease blood loss and to occlude inaccessible or unresectable portions of a lesion. In nine patients, embolization was the sole means of treatment for occluding an abnormal vascular shunt. Two patients (9%) experienced a minor transient neurologic change after the procedure.

Adolescent↗
PubMed1986

Radiographic findings in 32 cases of primary CNS lymphoma.

Computed tomographic (CT) or angiographic (or both) findings were analyzed in 32 cases of pathologically proved primary non-Hodgkin lymphoma of the central nervous system. CT scans were available in 28 of the 32 cases. Thirty lesions were found in the 28 cases. In comparison with previous literature, the frequency of involvement of deep central structures (30%), multiple lesions (11%), and subependymal lesions (4%) was lower and that of lesions in the periphery of the supratentorial compartment was higher (46%). In agreement with previous literature, most of the lesions were of increased density (63%), enhanced (100%), and enhanced homogeneously (71%). Twenty-nine of the 32 patients underwent cerebral angiography. In 12 patients, a homogeneous vascular stain was found that appeared in the late arterial or early venous phase and had a meningiomalike pattern. This staining pattern has not been emphasized sufficiently in previous literature. It was believed that such an angiographic pattern in a dense, homogeneously enhancing parenchymal lesion is suggestive of a primary lymphoma of the central nervous system. Magnetic resonance imaging was performed in one patient with two lesions, and both lesions demonstrated prolonged T2 relaxation times.

Adolescent↗
PubMed1984

Popliteal venous aneurysm as a source of pulmonary emboli in a male: case report.

A 48 year old male was admitted with pulmonary emboli. Subsequent investigation revealed the most probable source to be a left sided popliteal venous aneurysm. A second venogram performed shortly after the first did indeed reveal thrombus originating in the aneurysm and propagating up the superficial femoral vein. Popliteal venous aneurysm is an extremely rare entity, which heretofore has been described only in female patients.

Aneurysm↗
PubMedDate not supplied

T1-weighted MR imaging of the brain using a fast inversion recovery pulse sequence.

The purpose of this paper was to develop and evaluate a fast inversion recovery (FIR) technique for T1-weighted MR imaging of contrast-enhancing brain pathology. The FIR technique was developed, capable of imaging 24 sections in approximately 7 minutes using two echoes per repetition and an alternating echo phase encoding assignment. Resulting images were compared with conventional T1-weighted spin echo (T1SE) images in 18 consecutive patients. Compared with corresponding T1SE images, FIR images were quantitatively comparable or superior for lesion-to-background contrast and contrast-to-noise ratio (CNR). Gray-to-white matter and cerebrospinal fluid (CSF)-to-white matter contrast and CNR were statistically superior in FIR images. Qualitatively, the FIR technique provided comparable lesion detection, improved lesion conspicuity, and superior image contrast compared with T1SE images. Although FIR images had greater amounts of image artifacts, there was not a statistically increased amount of interpretation-interfering image artifact. FIR provides T1-weighted images that are superior to T1SE images for a number of image quality criteria.

Artifacts↗
PubMedDate not supplied

Primary progressive aphasia. An uncommon masquerader of psychiatric disorders.

Primary progressive aphasia is a recently described, uncommon language disorder with unclear etiological and clinical boundaries. The infrequency and ambiguity of the syndrome may prompt psychiatric consultation. The authors review the pertinent features of one such referral, including a brief literature review of the salient aspects of the differential diagnosis, and note the implications for appropriate treatment.

Agnosia↗
PubMedDate not supplied

MR findings in normal-pressure hydrocephalus: significance and comparison with other forms of dementia.

This study was undertaken to identify findings on magnetic resonance (MR) imaging that might possibly differentiate among several dementia states in the elderly or predict response to shunt therapy in patients with normal-pressure hydrocephalus (NPH). The MR findings were retrospectively reviewed in 54 patients who were divided into four clinical categories: NPH (17 patients), obstructive hydrocephalus (eight patients), Alzheimer disease (eight patients), and non-Alzheimer dementia (21 patients). Three MR findings were evaluated in each case: increased periventricular (PVS) and white matter (WMS) signal on T2-weighted images, CSF flow void sign (CFVS) in the aqueduct, and corpus callosum thinning. Neither the PVS/WMS nor corpus callosum thinning patterns were useful for distinguishing among the four clinical groups. At low field strength, the absence of a marked or moderate CFVS, however, may militate against a diagnosis of NPH. All 17 patients with NPH underwent a shunt procedure after the MR study. A better response to shunt therapy occurred in patients without WMS and with more severe PVS.

Adult↗
PubMedDate not supplied

Temporal lobe volume measurement from MR images: accuracy and left-right asymmetry in normal persons.

The effect of several magnetic resonance (MR) variables on the accuracy of volume measurements in phantom objects was investigated by use of an off-line automatic border-outlining and internal area pixel-counting computer program, and an optimal set of imaging variables was identified. Measurements were made of the temporal lobe volumes of a gross fixed brain specimen from MR image data. The range in accuracy was from -2 to +7%, and the standard deviation of the difference in right minus left lobe volume measurements obtained from the MR images and those obtained by use of Archimedes' principle was 1 cm3. This volumetric technique was applied to 25 normal persons, most of whom were right-handed. The median ratio of right to left temporal lobe volume was 1.16 (range 0.99-1.23). The nondominant temporal lobe was significantly larger than the dominant. The mean difference (95% confidence interval) between right and left volumes was 7 cm3 (6-9 cm3). This confidence interval was similar to that obtained when the variability within a subject (estimated from the gross fixed brain specimen) was taken into account. Unilateral temporal lobe atrophy, particularly in patients with temporal lobe epilepsy, should be interpreted from MR images with this range of discrepancy in normal left-right size in mind.

Adult↗
PubMedDate not supplied

Field strength in neuro-MR imaging: a comparison of 0.5 T and 1.5 T.

A study was undertaken comparing neurological magnetic resonance imaging at high (1.5 T) and mid (0.5 T) field strengths. Twenty-eight patients (20 head and 8 spine) from our routine case load volunteered to undergo two consecutive and identical MR studies on the two systems. The two MR systems were built by the same manufacturer and were equipped with essentially identical hardware and software. Individual patient studies were performed consecutively in adjacent MR suites, and pulse sequence parameters were replicated exactly at the two field strengths. One exception to this rule was that the second echo of the long TR sequence in the head was acquired with a narrow receiver bandwidth on the 0.5 T system. The resulting axial double echo long repetition time (TR) and sagittal short TR head images and sagittal short and double echo long TR spine images were graded by two blinded observers (senior staff neuroradiologists) on two levels. First, the images were graded for image quality, i.e., conspicuousness of artifacts and clarity in depiction of normal and pathologic anatomy. Second, diagnostic accuracy of MR was assessed relative to the clinical-pathologic diagnosis in each case. The image quality of the 1.5 T system was rated superior in both the head and spine for most specific items assessed. This observer preference for 1.5 T images did not, however, translate into greater diagnostic accuracy for the 1.5 T system in the head. Although the 1.5 T system did have a slight advantage in diagnostic accuracy in the spine, a significant difference was not found.

Brain↗
PubMedDate not supplied

Embolization of spinal dural arteriovenous fistula with polyvinyl alcohol particles: experience in 14 patients.

PURPOSE: To assess the effectiveness, initial and long term, of embolization using polyvinyl alcohol particles (PVA) particles in patients with spinal dural arteriovenous fistulas (SDAVF). METHODS: The initial treatment in 14 patients with SDAVF was embolization with PVA particles. Postembolization occlusion of the SDAVF was documented angiographically in all cases. RESULTS: All 14 patients initially showed an improvement in clinical symptoms, but the neurologic status of 11 patients subsequently deteriorated. Of the 11 patients who had recurrence of symptoms, nine had angiographically proven recurrences of their SDAVF while two had negative follow-up of spinal angiography. PVA embolization is ineffective for the treatment of SDAVF and is not without risk. CONCLUSION: On the basis of a literature review of the other two alternative treatments (operation or liquid adhesive embolization) available for SDAVF and our preliminary experience with N-butyl cyanoacylate (NBCA) embolization, we suggest that NBCA embolization be the initial treatment of choice for SDAVF; if that procedure is not possible, or is unsuccessful, then operation is recommended.

Aged↗
PubMedDate not supplied

Stereotactic third ventriculostomy: assessment of patency with MR imaging.

Ventricular CSF signal-intensity characteristics indicative of flowing CSF on MR images (CSF flow void) were analyzed in 20 patients who underwent a CT-based stereotactic third ventriculostomy for presumed internal obstructive hydrocephalus between October 1985 and June 1988. The status of all ventriculostomies was assessed postoperatively by radionuclide ventriculography. Postoperative MR and ventriculographic findings were correlated with the patients' subsequent clinical course. A CSF flow void in the anterior and inferior third ventricle, which seems to indicate vigorous pulsatile CSF flow through a functioning ventriculostomy, was present in all 19 patients who were clinically improved after ventriculostomy. In all 19 of these patients the radionuclide ventriculogram demonstrated normal CSF dynamics. One of the 20 patients did not improve postoperatively. The ventriculogram in this patient revealed delayed ventricular clearing and impaired CSF resorption, and the postoperative MR image did not demonstrate an anterior/inferior third ventricular CSF flow void. Eight of these patients were evaluated preoperatively by MR; one of these eight was the single nonimproved individual. None of the eight preoperative MR studies demonstrated a CSF flow void in the anterior/inferior third ventricle; however, this finding was present in seven of seven postoperative MR studies in clinically improved patients. We conclude that the presence of a CSF flow void in the anterior/inferior third ventricle on a postoperative MR examination is sufficient to document patency of a third ventriculostomy. The absence of this finding may be due to a nonpatent ventriculostomy or perhaps an extraventricular CSF obstruction. The more invasive ventriculogram may be reserved for this situation to distinguish between these latter two possibilities.

Adolescent↗