Emerging impact of CTA/perfusion CT on acute stroke thrombolysis in a community hospital.

Our objective was to retrospectively review the emerging role of CT, CTA, and perfusion CT (pCT) in the hyperacute stroke population of a community hospital. We reviewed 50 consecutive patients' records and imaging studies, who were treated with thrombolytic therapy within 6 h of symptom onset. Multidetector CT, CTA, and pCT studies were evaluated. Subsequent CT, magnetic resonance, or angiographic studies when available were correlated. Patients' clinical data at admission and outcomes at discharge were evaluated. Complications were tabulated. Of the 50 patients treated with thrombolytics, 37 had CT/CTA/pCT, the others non-contrast CT only. CT blood volume defect was present in a total of 14 patients, presaging permanent infarct in all. Arterial clot was seen in 28/37 CTAs (carotid "T" 6, MCA 16, vertebrobasilar 6). Viable penumbra was shown in 20/37; rescued penumbra was depicted after treatment in 14. 39 patients were treated with intravenous, nine with intra-arterial, two with both forms of thrombolysis. Modified Rankin score showed clinical improvement in 58%, three patients had complete recovery. Subsequent bleed was shown in two (4%), symptomatic in one (2%). Two patients died. Our experience suggests advanced CT is more sensitive to ischemia than routine CT, that salvageable penumbra can be identified, and that triage of patients with acute stroke for thrombolysis with CT/CTA/pCT is more robust than routine CT alone, and may improve outcomes in the community hospital setting.

Brown-Séquard syndrome secondary to spontaneous bleed from postradiation cavernous angiomas.

SUMMARY: The spontaneous occurrence of acute Brown-Séquard syndrome is an extremely rare event, with most reported cases being secondary to spontaneous epidural hematomas and spinal cord ischemia. We report a rare case of Brown-Séquard syndrome from spontaneous intraspinal hemorrhage in a patient with multiple cavernous angiomas in the spinal cord secondary to craniospinal radiation in childhood. Postulated mechanisms leading to the condition include postradiation molecular changes and venous occlusion.

MR of Zellweger syndrome.

PURPOSE: To determine characteristic MR imaging features of Zellweger syndrome. METHODS: Clinical records, laboratory records, and MR studies of six patients with Zellweger syndrome were reviewed retrospectively. MR studies were examined for the state of myelination; the presence, extent, and morphologic appearance of cerebral cortical anomalies; the status of the cerebellar cortex, basal nuclei, and brain stem; and the presence or absence of any regions of abnormal signal intensity. RESULTS: The diagnosis of Zellweger syndrome was established in all patients by clinical findings combined with laboratory and MR results. All patients had impaired myelination and diffusely abnormal cortical gyral patterns that consisted of regions of microgyria (primarily in the frontal and perisylvian cortex) together with regions of thickened pachygyric cortex (primarily perirolandic and occipital). The pachygyric regions were in the form of deep cortical infoldings. Germinolytic cysts were visible in the caudothalamic groove in all patients, seen best on coronal or sagittal T1-weighted images. One patient had T1 shortening in the bilateral globus pallidus, presumably related to hepatic dysfunction and hyperbilirubinemia. CONCLUSION: The combination of hypomyelination, cortical malformations that are most severe in the perisylvian and perirolandic regions, and germinolytic cysts are highly suggestive of Zellweger syndrome in the proper clinical setting.

Cardiac tumors: assessment with Gd-DTPA enhanced MR imaging.

Previous studies have shown the value of MR imaging for the identification of cardiac masses. The distinction of intramural tumors from normal myocardium may be equivocal because of the similarity of signal intensity between tumor and normal myocardium on ECG-gated SE images. The purpose of this study was to assess the role of Gd-DTPA for improving the contrast between cardiac tumors and myocardium. Four patients with established or suspected cardiac tumors were imaged with a 1.5 T imager. The T1-weighted images (TR = RR interval, TE = 20-30 ms) were obtained before and immediately after the intravenous injection of Gd-DTPA, at a dosage of 0.1 mmol/kg. Tumors were identified in three patients. All tumors were isointense to the myocardium in precontrast images but demonstrated differential enhancement relative to myocardium after the administration of Gd-DTPA. Two tumors were hyperintense relative to myocardium, and the third was mostly hypointense, surrounded by a hyperintense rim. In the remaining case, no tumor was found and the myocardium was homogeneously enhanced on postgadolinium images. Gadolinium DTPA can produce differential enhancement of tumor from normal myocardium and therefore demonstrate intramural masses.

Cervical paraspinal calcification in collagen vascular diseases.

Although soft-tissue calcification is common in collagen vascular disease, paraspinal calcification in the cervical spine has not been described before. We studied five women with large, lobulated, predominantly homogeneous calcific masses centered on synovial articulations in the neck. Changes consisting of either osteolysis or erosions were evident. All patients had radiculopathy, focal pain, or stiffness. In two patients, the presence of hydroxyapatite crystals was confirmed on biopsy. Symptomatic cervical paraspinal calcifications in patients with collagen vascular disease cause large soft-tissue masses that mimic tumoral calcinosis.

MR of soft tissue chloroma in a patient presenting with left public and hip pain.

A patient with a history of chronic granulocytic leukemia presented with hip and pubic pain. Magnetic resonance study showed a mass infiltrating the obturator externus muscle, which was biopsied under CT guidance. Pathology of the mass was chloroma. Magnetic resonance can be extremely valuable in determining the etiology of hip and pubic pain in patients with a history of leukemia.

The wedge-shaped cord terminus: a radiographic sign of caudal regression.

Imaging studies from 13 patients with caudal regression were reviewed retrospectively to assess the spectrum and findings of this anomaly. Seven patients were evaluated with MR and six with myelography (supplemented with CT in three). The level of regression varied from T9 to the coccyx. Although osseous abnormalities were more readily identified and characterized by CT, MR effectively depicted the level of vertebral regression, presence of central spinal stenosis, and vertebral dysraphic anomalies. MR demonstrated a characteristic wedge-shaped (longer dorsally) cord terminus in seven of the patients. When this characteristic cord terminus is seen, imaging of the lower lumbar and sacral regions should be performed to verify the diagnosis of caudal regression. Tethered spinal cords have been described in patients with caudal regression and were seen in two of our patients. We present the first cases of individuals who have survived with absence of vertebrae above the T10 level and an unusual case of caudal regression with absent lumbar vertebrae and preserved lower sacral and coccygeal vertebrae. The syndrome of caudal regression encompasses a wide spectrum of pathology that is analyzed well by modern imaging techniques.

High-resolution MR imaging of pituitary microadenomas at 1.5 T: experience with Cushing disease.

The MR images of 27 patients with clinically and biochemically suspected Cushing disease were evaluated retrospectively in a blinded fashion. The MR interpretation was compared with detailed operative diagrams and operative and pathologic reports. The examinations were performed on a 1.5-T MR system with thin-section sagittal and coronal T1-weighted (short TR/TE) images. Each pituitary half was considered separately (54 "halves"). Twenty-one pituitary halves were considered to have glandular abnormalities on MR. Compared with surgical findings, 17 MR findings were true positives and four were false positives (one pars intermedia cyst, three normal tissue). Of the 33 pituitary halves considered normal on MR, 26 were true negatives and seven were false negatives. MR had an overall sensitivity of 71% and a specificity of 87% for these adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas. A focal glandular hypointensity identified on coronal images was the most sensitive predictor of adenoma location. Sagittal images were not useful in either detection or localization. Upward convexity of the gland and deviation of the stalk were less useful indicators. Abnormalities of the sellar floor were the least reliable. In comparison with the capabilities of CT detection of microadenomas described in the current literature, it appears that high-field thin-section MR of the sella is the most sensitive imaging method for preoperative localization of ACTH-secreting adenomas in patients with Cushing disease.

Posterior pituitary ectopia: an MR feature of pituitary dwarfism.

Using high-field-strength, 1.5-T, high-resolution MR, we identified the following complex of neurohypophyseal abnormalities in each of five pituitary dwarfs: (1) severe hypoplasia or total absence of the infundibulum; (2) absence of the posterior pituitary bright spot in its normal location; and (3) a 3-8-mm tissue nodule at the median eminence exhibiting lipidlike signal on T1-weighted images. On the basis of its signal features and the clinical absence of diabetes insipidus in these patients, the median eminence nodule appears to represent an ectopic and functional posterior pituitary gland. We propose that this anatomic derangement is the end result of a localized defect of developmental origin, possibly ischemic in nature, and involving principally the infundibular stem. Thus, human growth hormone deficiency could result from perinatal disruption of the peri-infundibular hypophyseal portal system, which in turn impairs anterior pituitary function through deprivation of direct delivery of crucial hypothalamic-releasing factors. Finally, we suggest that the trophic influence of continued axonal neurosecretion at the median eminence engages proliferation of rest cell pituicytes; a process that induces formation of an ectopic and functional posterior pituitary gland, complete with its characteristic bright spot.

Rathke cleft cysts: CT, MR imaging, and pathologic features.

The authors retrospectively reviewed the clinical, computed tomography (CT), and magnetic resonance (MR) imaging findings in seven patients with pathologically proved Rathke cleft cysts. All the cysts were located in the anterior sella turcica or the anterior suprasellar cistern. Five cysts had both intra- and suprasellar components, one was entirely intrasellar, and the other was predominantly suprasellar in location. The size of the cysts ranged from 8 to 20 mm. CT scans demonstrated low-density homogeneous lesions in four cases. On MR images of three of these four cases, the cysts had the same intensity as cerebrospinal fluid on T1- and T2-weighted images, while in the fourth case, the cyst was hyperintense on the T1-weighted images. In the remaining three cases, CT showed slight hyperdensity relative to brain parenchyma, suggestive of contrast enhancement. MR showed signal heterogeneity of these lesions with focal components of diminished signal intensity of T2-weighted images. These same foci appeared iso- to slightly hyperintense on T1-weighted images.

Hyperparathyroidism: comparison of MR imaging with radionuclide scanning.

Twenty-three patients with hyperparathyroidism were evaluated preoperatively with magnetic resonance (MR) imaging. Twenty patients also underwent thallium-201/technetium-99m scintigraphy. Of 22 patients with primary hyperparathyroidism, 12 had persistent or recurrent disease. One had secondary hyperparathyroidism due to end-stage renal disease. MR imaging allowed accurate localization of abnormal parathyroid glands in 64% evaluated prospectively and 82% evaluated retrospectively. Scintigraphy allowed localization of 60% evaluated prospectively and 70% retrospectively. The two imaging modalities together allowed detection of 68% evaluated prospectively and 91% retrospectively. MR imaging allowed detection of two of five mediastinal adenomas evaluated prospectively and four of five retrospectively. In patients who underwent both imaging studies, MR was more successful in those with previous neck surgery (73% evaluated prospectively and 91% retrospectively) than in those with no prior surgery (57% prospectively and 71% retrospectively). Scintigraphy allowed accurate localization in 64% evaluated prospectively and 64% retrospectively in patients with previous surgery versus 57% prospectively and 86% retrospectively in patients with no prior neck surgery. Four false-positive results were obtained with MR imaging and three with scintigraphy. MR imaging was useful for parathyroid localization in patients with hyperparathyroidism, particularly in patients requiring additional surgery.

Effects of beta-adrenergic blockade on the natural progression of myocardial infarct size and compensatory hypertrophy.

Using contrast-enhanced computed tomography, the effects of beta-adrenergic blockade were assessed on experimentally produced myocardial infarcts in dogs evaluated serially over the course of approximately 1 month. Infarct size, initial perfusion defect (jeopardized segment) and noninfarcted muscle mass were studied in two groups of conditioned mongrel dogs. Group 1 (n = 11) served as the control group and Group 2 (n = 10) was pretreated with propranolol (2 mg/kg). Each animal in the propranolol-treated group was given identical amounts of the agent twice daily for 7 days after coronary occlusion. Both groups developed increases in the noninfarcted muscle mass of the left ventricle (compensatory hypertrophy). The mean increase averaged 19.8% over 30 days when the two groups were included together. Infarct size was smaller in the propranolol-treated group, and averaged 28% less (p less than 0.05) than that of the control group 30 days after initial myocardial infarction. Thus, pharmacologic interventions were shown by computed tomography to alter the size of an acute experimental myocardial infarct, particularly when examined over the time course of infarct healing. Moreover, compensatory hypertrophy occurred in both the control and propranolol-treated groups.

Analysis of phase-angle histograms from equilibrium radionuclide studies: correlation with semiquantitative grading of wall motion.

Quantitative wall motion assessment from gated radionuclide left ventriculograms using phase analysis was studied in 14 subjects (6 normal volunteers and 8 patients with previous acute myocardial infarction). The standard deviation and skewness of the phase-angle histograms were determined from both global and segmental left ventricular (LV) regions of interest (septal, apical and posterolateral). Studies were performed at rest, after administration of atropine and after combined administration of phenylephrine and atropine. Both the standard deviation and skewness showed significant correlations with semiquantitative wall motion scoring. From the global analyses, the highest correlations were found after atropine administration (r = 0.86, p less than 0.001 for standard deviation and r = 0.72, p less than 0.001 for skewness). Nevertheless, deterioration in global wall motion scores correlated poorly with directional changes in standard deviation (r = 0.06, difference not significant) or skewness (r = 0.33, p less than 0.05). No significant correlation between skewness or change in skewness and wall motion scores were found with the segmental analyses. The maximal correlation between segmental standard deviation and segmental wall motion grading was again noted after atropine administration (r = 0.68, p less than 0.001), but deterioration in grading did not correlate with similar deterioration of the standard deviation (r = -0.05, difference not significant). Based on 90% confidence limits for normal standard deviation and skewness, an abnormal standard deviation (greater than 14.5) identified 13 of 28 wall motion disorders (sensitivity 46%), whereas an abnormal skewness (greater than 1.4) identified 1 of 28 wall motion disorders (sensitivity 4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Nuclear magnetic resonance analysis of acute and chronic myocardial infarction in dogs: alterations in spin-lattice relaxation times.

The purpose of this study was to evaluate the effects of acute and chronic ischemic injury on myocardial spin-lattice relaxation times (T1) in dogs. Ligation of the left anterior descending coronary artery was performed on 23 dogs which were divided into four experimental groups and killed at 3 hours (n = 6), 4 days (n = 6), 21 days (n = 5), and 56 days (n = 6) after coronary occlusion. T1 was measured in vitro with a 2.5 kg nuclear magnetic resonance (NMR) spectrometer using tissue from ischemic and control areas of the myocardium. Both the 3-hour and 4-day groups showed prolongations in T1 (p less than 0.01) for tissue from the ischemic area. In the 21-day group, two infarcts showed an increase in T1, two showed a decrease in T1, and one showed no significant change. The 56-day old infarcts had a lower mean value for T1 than control myocardium (p less than 0.01). The differences in myocardial water content between control and infarcted myocardium were found to parallel changes in T1 values in each experimental group. Pathologic examination of the myocardial scar from 21- and 56-day-old infarcts revealed extensive fibrosis in the infarcts with lower T1 values and tissue water contents than control myocardium. We conclude that myocardial edema in 3-hour and 4-day-old infarcts results in association with prolongations in T1. Twenty-one-day-old infarcts may be edematous (with increased T1) or fibrotic (with T1 values lower than normal myocardium), while 56-day-old infarcts are fibrotic and have shorter T1 values than normal myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of pulmonic and aortic constriction on regional left ventricular thickening dynamics, geometry and the radius of septal curvature. Analysis by gated computed transmission tomography.

We evaluated the effects of aortic and pulmonic constriction on cross-sectional cardiac dynamics using prospectively gated computed transmission tomography (CT) in six dogs in order to evaluate 1) the effect of altering the end-diastolic trans-septal pressure gradient on the radius of septal curvature, and 2) the effect of right ventricular overload on regional left ventricular geometry and wall thickening dynamics. Cross-sectional CT data were obtained in a control state, at two incrementally higher levels of right ventricular end-diastolic pressure produced by constriction of the pulmonary artery (PA1 and PA2) and then at one higher level of left ventricular end-diastolic pressure resulting from acute aortic constriction (Ao). Using fluid-filled polyethylene catheters, we measured right and left ventricular pressures simultaneous with the image acquisition. The measured radius of septal curvature was then normalized by the calculated average radius derived from the left ventricular area at end-diastole. The end-diastolic radius of septal curvature ratio increased as delta [LVEDP-RVEDP] declined (from 1.03 +/- 0.13 at control; 1.20 +/- 0.18 PA2; 1.27 +/- 0.14 PA2 and 0.87 +/- 0.11 Ao). As this LVEDP-RVEDP gradient declined (ie, RVEDP increased in proportion to LVEDP) septal wall thickening declined (P less than 0.005), with significantly less change in left ventricular anterior or lateral wall thickening. With PA hypertension, LV end-diastolic volume and percent delta volume significantly declined (P less than 0.005) while RV end-diastolic volume increased. With PA pressure overload, septum-free wall distance declined (P less than 0.01) as did percent shortening along this dimension (P less than 0.01). We conclude that predictable changes in LV and RV dynamics occur when trans-septal pressure gradients change.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained venous occlusion plethysmography: effects on protein osmotic pressure, intravascular volume, and capillary filtration.

In six acutely anesthetized, mechanically ventilated mongrel dogs, we evaluated sequential changes (over 30 minutes) of sustained forelimb venous occlusion (occlusion pressures 30 to 65 mm Hg) on strain gauge dimension, radionuclide blood pool emissions, and venous, subcutaneous, and intramuscular pressures (Wick technique). Forelimb intravascular volume (assessed by decay-corrected radionuclide counts/unit time) changed by a mean of only -1.2 +/- 2.8% (+/- SEM) and thus was ignored in the calculation of filtration rate. Forelimb (distal to the occlusion site) hematocrit changed insignificantly (45.3 +/- 1.4% at the control point to 48.2 +/- 1.1% at 30 minutes), colloid osmotic pressure rose slightly 19.4 +/- 1.4 mm Hg to 22.7 +/- 1.6 mm Hg, p less than 0.01), and serum osmolality remained unchanged. During sustained occlusion, venous pressure remained constant, subcutaneous pressure rose (-0.7 +/- 1.2 mm Hg control vs 0.5 +/- 1.4 mm Hg at 30 minutes, p less than 0.05), and intramuscular pressure also rose (-0.4 +/- 1.1 mm Hg to 2.6 +/- 1.6 mm Hg, p less than 0.01). Driving pressure, defined by venous pressure - oncotic pressure less the average of intramuscular and subcutaneous pressure declined slightly over the 30 minutes of the study (27.8 +/- 5.5 mm Hg to 23.3 +/- 1.3 mm Hg, p less than 0.05). The relationship between either the initial driving pressure or the initial difference between venous and protein osmotic pressure correlated (r = 0.83 for both) well with strain gauge estimates of capillary fluid flux (evaluated by the change in forelimb strain gauge dimension over time and given as cc/100 cc forelimb volume/min).(ABSTRACT TRUNCATED AT 250 WORDS)