Biomedical subjects

Ellen G Hoeffner

Publications and source records attributed to Ellen G Hoeffner.

5 recordsLinked to original sources

PubMed2005

Cerebral perfusion imaging.

There are multiple imaging techniques available to assess cerebral perfusion, including positron emission tomography (PET), xenon computed tomography (XeCT), single photon emission computed tomography (SPECT), perfusion-weighted MRI (PWI), and perfusion computed tomography (PCT). Current interest has focused mainly on their use in the setting of acute brain ischemia. Perfusion imaging may be able to distinguish infarcted from salvageable ischemic tissue as a guide to treatment. Perfusion techniques may also be helpful in cases of chronic ischemia, post-subarachnoid hemorrhage vasospasm, trauma, and contemplated therapeutic carotid artery occlusion.

Brain↗

PubMed2004

Cerebral perfusion CT: technique and clinical applications.

Perfusion computed tomography (CT) is a relatively new technique that allows rapid qualitative and quantitative evaluation of cerebral perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The technique is based on the central volume principle (CBF = CBV/MTT) and requires the use of commercially available software employing complex deconvolution algorithms to produce the perfusion maps. Some controversies exist regarding this technique, including which artery to use as input vessel, the accuracy of quantitative results, and the reproducibility of results. Despite these controversies, perfusion CT has been found to be useful for noninvasive diagnosis of cerebral ischemia and infarction and for evaluation of vasospasm after subarachnoid hemorrhage. Perfusion CT has also been used for assessment of cerebrovascular reserve by using acetazolamide challenge in patients with intracranial vascular stenoses who are potential candidates for bypass surgery or neuroendovascular treatment, for the evaluation of patients undergoing temporary balloon occlusion to assess collateral flow and cerebrovascular reserve, and for the assessment of microvascular permeability in patients with intracranial neoplasms. This article is a review of the technique, clinical applications, and controversies surrounding perfusion CT.

Blood Volume↗

PubMed2004

Carotid perfusion CT with balloon occlusion and acetazolamide challenge test: feasibility.

Carotid balloon test occlusion (BTO) is used to assess the collateral circulation and cerebrovascular reserve in patients in whom carotid artery occlusion is contemplated. Eight patients in whom the test was successful were evaluated with perfusion computed tomography (CT) in the resting state and after acetazolamide challenge. Three of the patients showed symmetric blood flow and normal response to acetazolamide. One of them underwent permanent carotid occlusion and did not develop any delayed ischemic stroke. The remaining five patients showed asymmetric blood flow. One of them had markedly low blood flow and abnormal response to acetazolamide. The patient developed ipsilateral hemispheric stroke following permanent carotid occlusion after the superficial temporal artery to middle cerebral artery bypass graft occluded. In the other four patients, the steal phenomenon was seen in ipsilateral and contralateral hemispheres. Although definitive quantitative values for perfusion CT are not yet standardized, it may be feasible to predict that the patients with symmetric blood flow and normal acetazolamide-enhanced challenge test results will do well after permanent carotid occlusion. Patients with asymmetric blood flow and abnormal response to the acetazolamide challenge test may require a revascularization procedure to protect them from delayed ischemic stroke.

Acetazolamide↗

PubMed2004

Delineation of lateral tentorial sinus with contrast-enhanced MR imaging and its surgical implications.

BACKGROUND AND PURPOSE: The lateral tentorial sinus (LTS) has not been well described in the imaging literature. The aim of this study was to investigate the value of MR imaging in assessing the LTS, which may provide guidance for preoperative planning. METHODS: Fifty-five adult patients underwent MR imaging of the brain. Four neuroradiologists evaluated the studies for delineation of the LTS and its branches. Presence of arachnoid granulation and dominance of the venous drainage also were reported. RESULTS: An LTS was detected in 104 of 110 lobes. The LTS in each lobe was classified as type I (candelabra) in 30 (28.8%), type II (independent veins) in 22 (21.1%), and type III (venous lakes) in 37 (35.5%); in 15 (14.4%) of the lobes, the LTS was indeterminate. LTS branches were inconsistently detected, with the exception of the vein of Labbé (VL). Five of eight branches were seen in approximately half of the cases. The VL was identified in 94 (85.4%) lobes. Among these, 53 (56.4%) were draining into the LTS and 22 (23.4%) into the transverse sinus; in 19 (20.2%) cases, the terminal portion was not visualized. The right transverse sinus was dominant in 19 (34.5%) patients and the left in 18 (32.7%); codomination was present in 18 (32.7%) cases. At least one arachnoid granulation was seen in the transverse sinus in 27 (49.1%) patients. CONCLUSION: In many instances, the LTS and VL drainage patterns were well delineated on routine MR images. For selected cases, this information may be crucial during lateral skull base surgery to avoid venous infarct.

Adult↗

PubMedDate not supplied

Computed tomography perfusion of squamous cell carcinoma of the upper aerodigestive tract. Initial results.

OBJECTIVE: To define the computed tomography (CT) perfusion characteristics of head and neck squamous cell carcinoma. METHODS: Fourteen consecutive patients with untreated squamous cell cancers of head and neck underwent CT of the head and neck along with CT perfusion imaging through the primary site. For the perfusion studies, CT density changes in blood and tissues were kinetically analyzed using the commercially available CT Perfusion 2 software (General Electric Medical Systems. Milwaukee, WI) on a GE Advantage Windows workstation. This yielded parameter maps of fractional tissue blood volume (mL/100 g), blood flow (mL x 100 g(-1) x min(-1)), mean transit time (s), and microvascular permeability surface area product (mL x 100 g(-1) x min(-1)). One head and neck radiologist analyzed perfusion data. Regions of interest (ROI) were placed over the primary tumor site, tongue base, and adjacent muscle groups. The average values of tissue blood volume (BV), blood flow (BF), mean transit time (MTT), and capillary permeability surface area product (CP) were then calculated for the tumor and compared with the average values for the tongue base and adjacent musculature. To determine a statistically significant difference between the tumor and muscle parameters, the Wilcoxon sign test, a nonparametric test for paired data, was employed. RESULTS: The average values of CP, BF, and BV were higher in primary tumor (41.9, 132.9, 6.2, respectively) than in tongue base or adjacent muscular structures. The MTT was reduced in primary tumors (4.0) compared with adjacent normal structures. The above differences were statistically significant (P<0.05). CONCLUSIONS: We obtained baseline perfusion data for head and neck squamous cell cancers and compared it with adjacent normal structures. Our initial results suggest that CT perfusion parameters (CP, BF, BV, and MTT) can be used to help differentiate head and neck squamous cell carcinoma (SCCA) from adjacent normal tissue.

Carcinoma, Squamous Cell↗