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R Gilberto Gonzalez

Publications and source records attributed to R Gilberto Gonzalez.

59 records · Page 4Linked to original sources
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Total occlusion versus hairline residual lumen of the internal carotid arteries: accuracy of single section helical CT angiography.

BACKGROUND AND PURPOSE: Routine carotid sonography and MR angiography cannot reliably detect the markedly reduced flow velocities associated with very severe carotid stenosis. In this study, we sought to evaluate the accuracy of single row detector helical CT angiography in distinguishing hairline residual lumen from total occlusion of severely stenosed internal carotid arteries (ICAs). METHODS: From our departmental data base of single row detector CT angiography studies performed for evaluation of ICA occlusive disease, 21 cases were identified with evidence of either hairline residual lumen or total occlusion on correlative conventional catheter radiographic arteriograms; these included seven cases of proved hairline residual lumen and 14 cases of proved total occlusion. Two neuroradiologists, blinded to the radiographic arteriography results, graded the diseased ICA on each CT angiogram as definitely occluded, probably occluded, indeterminate, probably patent, or definitely patent. Receiver operating characteristic curves were generated for each neuroradiologist. RESULTS: At an operating point on the receiver operating characteristic curve corresponding to 90% sensitivity, the first reader achieved 95% specificity and the second reader achieved 80% specificity for distinguishing hairline residual lumen from total occlusion. Absolute accuracy rates were 95% and 85%, respectively. No significant difference in accuracy was observed between the two readers (P =.28, two-tailed t test). CONCLUSION: Single row detector CT angiography can distinguish total ICA occlusion from hairline residual lumen with a high degree of accuracy. In equivocal cases, conventional catheter arteriography may be desirable to confirm the diagnosis.

Aged↗
PubMedDate not supplied

Characterization and evolution of diffusion MR imaging abnormalities in stroke patients undergoing intra-arterial thrombolysis.

BACKGROUND AND PURPOSE: Lesions revealed by pretreatment diffusion-weighted imaging (DWI) may not progress to infarction, and apparent diffusion coefficient (ADC) or DWI thresholds for tissue viability may exist. We evaluated the evolution of abnormal DWI findings in patients with acute stroke who underwent thrombolysis. METHODS: Sixteen patients with acute occlusion of the anterior circulation underwent DWI followed by intra-arterial thrombolysis; follow-up CT or MR imaging was performed after reperfusion therapy. Lesion volumes were measured on all images. In three patients with abnormal DWI findings that appeared normal at follow-up, ADC values, ADC ratios, and DWI ratios were obtained on a section-by-section basis in the DWI-hyperintense regions that were either abnormal or normal at follow-up. RESULTS: In three patients, part of the DWI-hyperintense tissue appeared normal and part appeared abnormal at follow-up imaging. In one of these patients, the lesion decreased by -35.6%. In the other two, lesion growth appeared in regions that appeared normal at initial DWI: in one, the overall change in size was -2.4%, and in the other, the lesion increased by 89.8%. Respective mean changes at follow-up in normal-appearing and abnormal-appearing regions were: ADC, 731.7 x 10(-6) mm(2)/s and 650.4 x 10(-6) mm (2)/s; ADC ratio, 0.92 and 0.78; and DWI ratio, 1.16 and 1.32 (P <.001 for all measures). CONCLUSION: In patients with acute stroke who undergo intra-arterial thrombolysis, most abnormal, pretreatment DWI findings indicate eventual infarction. In 19% of the patients described herein, DWI-hyperintense regions appeared normal at follow-up. ADC values, ADC ratios, and DWI ratios may be useful in identifying the portion of abnormal tissue that is potentially salvageable after reperfusion therapy.

Acute Disease↗
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Gadolinium-enhanced CT angiography of the circle of Willis and neck.

CT angiography (CTA) of the cervical and intracranial vessels is a rapid, noninvasive, and relatively inexpensive technique for the evaluation of vascular abnormalities. Contraindications to the use of contrast media, however, can preclude use of iodinated agents for CTA. We report the use of gadolinium as contrast agent for CTA of the head and neck in three patients with contraindications to iodinated contrast agents.

Aged↗
PubMedDate not supplied

Parenchymal abnormalities associated with cerebral venous sinus thrombosis: assessment with diffusion-weighted MR imaging.

BACKGROUND AND PURPOSE: The common entity cerebral venous sinus thrombosis is associated with the poorly characterized imaging finding of parenchymal abnormalities; diffusion-weighted imaging has offered some insight into these manifestations. We assessed the relationship between the diffusion constant from apparent diffusion coefficient (ADC) maps in patients with cerebral venous thrombosis (CVT) with follow-up imaging findings and clinical outcome. METHODS: We evaluated the medical records and T2-weighted MR images of 13 patients with CVT complicated by intraparenchymal abnormality. Diffusion-weighted (DW) images and ADC maps were evaluated for increased, decreased, or unchanged signal intensity and were compared with signal intensity of contralateral, normal-appearing brain. In addition, ADCs were obtained in nine pixel regions of interest in abnormal regions in eight of the 13 patients. RESULTS: Eight patients had superficial CVT, and five had superficial and deep CVT. CVT of deep veins was associated with deep gray nucleus and deep white matter abnormalities, whereas superficial CVT was associated with cortical and subcortical abnormalities. Twenty-four nonhemorrhagic lesions were identified in 10 of 13 patients on the basis of follow-up imaging findings. Four patients without seizures had lesions with decreased diffusion that appeared hyperintense on follow-up T2-weighted images, three patients with seizures had lesions with decreased diffusion that resolved, and seven patients had lesions with increased diffusion that resolved. Three of 10 patients had more than one lesion type. No difference was noted in mean ADCs for lesions with decreased diffusion that resolved compared with lesions with decreased diffusion that persisted. CONCLUSION: DW imaging in these patients disclosed three lesion types: lesions with elevated diffusion that resolved, consistent with vasogenic edema; lesions with low diffusion that persisted, consistent with cytotoxic edema in patients without seizure activity; and lesions with low diffusion that resolved in patients with seizure activity. This information may be important in prospectively determining severity of irreversible injury and in patient treatment.

Adolescent↗