Michael A. Mikhael

Effect of the Extent of Surgical Resection on Survival and Quality of Life in Patients with Supratentorial Glioblastomas and Anaplastic Astrocytomas

Thirty-one patients operated upon for supratentorial glioblastomas or anaplastic astrocytomas were studied to evaluate the effect of the extent of surgical resection on the length and quality of survival. The median age was 50 years and the median preoperative Karnofsky rate was 80. Twenty-one patients (68%) had glioblastoma multiforme, and 10 patients (32%) had anaplastic astrocytoma. Early postoperative enhanced computed tomography was used to determine the extent of tumor resection. Gross total tumor resection was accomplished in 19 patients (61%), and subtotal resection was performed in 12 patients (39%). The two groups were comparable regarding age, sex, pathological condition, preoperative Karnofsky rating, tumor location, postoperative radiation therapy, and postoperative chemotherapy (P greater than 0.05). The gross total resection group lived longer than the subtotal resection group by life table analysis (P less than 0.001; median survival of 90 and 43 weeks, respectively). Postoperatively, the mean functional ability measured by the Karnofsky rating was significantly increased in the gross total resection group (P = 0.006), but not in the subtotal resection group (P greater than 0.05). The difference in degree of change between preoperative and postoperative Karnofsky rating in the two groups was statistically significant (P = 0.002). The gross total resection group spent significantly more time after the operation in an independent status (Karnofsky rating greater than or equal to 80) compared to the subtotal resection group (P = 0.007; median time of 185 and 12.5 weeks, respectively). Gross total resection of supratentorial glioblastomas and anaplastic astrocytomas is feasible and is directly associated with longer and better survival when compared to subtotal resection.

Supratentorial Gliomas: Surgical Considerations and Immediate Postoperative Results Gross Total Resection versus Partial Resection

Forty-two patients with supratentorial gliomas not involving the basal ganglia (extraganglionic) were studied pre- and postoperatively with computed tomographic (CT) scans to evaluate the effect of the extent of surgical resection on the immediate postoperative results. Thirty-three patients (79%) had malignant astrocytic gliomas (glioblastoma or anaplastic astrocytoma), 4 patients (10%) had well-differentiated astrocytomas, and 5 (12%) had oligodendrogliomas. The median age was 58 years, and the median Karnofsky rating was 70. There was no operative mortality. Six patients (14%) had surgical complications. A gross total resection was defined as the absence of any abnormal enhancement on the postoperative CT scan. A nearly gross total resection had been accomplished when less than 10% of the preoperatively enhancing mass was still seen. A partial resection was indicated by the presence of more than 10% of the enhancing lesion on the postoperative CT scan. A gross total or nearly gross total resection was accomplished in 36 patients (86%), and an improved or stable postoperative neurological status was present in 35 of these patients (97%). In contrast, the rate of neurological morbidity after a partial resection was 40%. Supratentorial extraganglionic gliomas, regardless of their histological type, generally were well-circumscribed lesions except at the level of the ventricular wall, where glioblastomas and anaplastic astrocytomas blended with the subependymal white matter from which they seemed to arise.

Differentiation of cerebellopontine angle neuromas and meningiomas with MR imaging.

Postcontrast CT of the temporal bone is the neuroradiological study of choice for investigation of cerebellopontine angle (CPA) and internal auditory canal (IAC) lesions. Nonenhancing or small lesions may need CT combined with air or metrizamide cisternography for their detection. Magnetic resonance (MR) imaging has shown interesting capabilities as a noninvasive study for the visualization of the I AC, the neural bundle entering the canal, the brain stem, and cerebellum. In the present series of 24 cases, MR imaging detected the lesion in all 11 verified tumors. We feel that MR can replace invasive air and metrizamide cisternography in the diagnosis of CPA lesions and can help in the differentiation between acoustic neuromas and meningiomas.

MR imaging in spinal echinococcosis.

A case of spinal echinococcosis with dorsal spinal cord compression is presented and the findings on plain radiography, polytomography, myelography, CT, and magnetic resonance (MR) imaging are discussed. Although CT and MR are complementary studies for the diagnosis of spinal echinococcosis, MR is the study of choice for prolonged follow-up of complicated cases.

Cerebrovascular Changes in Neurofibromatosis

Vascular changes in neurofibromatosis are most commonly described in the renal arteries. In the present study, two children with neurofibromatosis and cerebral vascular occlusive changes demonstrated by cerebral angiography are reported. Although focal neurological findings in children with neurofibromatosis are often due to tumours, the sudden development of neurological symptoms in such cases should alert paediatricians to the possibility of cerebral vascular disease.

MR imaging of pituitary tumors before and after surgical and/or medical treatment

Four hundred fifteen cases of suspected pituitary tumors were examined by CT and magnetic resonance (MR). Forty-one microadenomas and 26 large sellar-suprasellar pituitary tumors were diagnosed and surgically removed (61 cases) or treated with bromocriptine (six cases). The present study demonstrated that (a) in cases of microadenomas, MR was more accurate than CT in three cases, as accurate as CT in 33 cases, but missed six cases diagnosed on CT, when MR images were suboptimal (thicker than 5 mm); (b) when the sellar-suprasellar mass was markedly constricted at the diaphragma sellae on MR sagittal slices (16 cases), transsphenoidal surgical approach was not only insufficient for total removal but could be dangerous, as the remaining suprasellar portion may rapidly increase in size following surgery from postoperative hemorrhage and/or acute edema with severe obstructive hydrocephalus (three cases) and/or acute blindness (two cases); (c) hemorrhage in pituitary tumors was easily seen on MR and missed on CT; (d) coronal MR slices visualized the carotid siphon obviating the need for angiography to rule out intrasellar aneurysm, which can mimic pituitary tumor on contrast CT; (e) postoperative MR was needed before considering radiotherapy to visualize accurately the relation of the optic chiasm to the residual tumor and to follow up its gradual change in size; (f) finally, in cases treated with bromocriptine, MR was more accurate than CT in following the gradual decrease of pituitary tumor.

A Method to Quantitatively Measure Transcapillary Transport of Iodinated Compounds in Canine Brain Tumors with Computed Tomography

We present a quantitative method for determining a blood-to-tissue influx constant (K1), a tissue-to-blood efflux constant (k2), and tissue plasma vascular space (Vp) that uses a computed tomographic (CT) scanner to make tissue and plasma measurements of the concentration of an iodinated compound. Meglumine iothalamate was infused intravenously over time periods of 0.5–5 min, up to 49 CT scans were obtained at one brain level, and arterial plasma was sampled over a 30- to 40-min period. K1, k2, and Vp were calculated for each voxel of the 320 × 320 matrix, using a two-compartment pharmacokinetic model and nonlinear least-squares regression. The method was used in dogs with avian sarcoma virus–induced brain tumors. As many as four studies on different days were done in the same animal. In tumor-free cortex, K1 of meglumine iothalamate was 2.4 ± 1.7 μl g−1 min−1 (mean ± SD) and Vp was 3.4 ± 0.5 ml 100 g−1. Mean whole-brain tumor K1 values ranged from 3.3 to 97.9 μl g−1 min−1; k2 ranged from 0.032 to 0.27 min−1; and Vp ranged from 1.1 to 11.4 ml 100 g−1. These values were reproducible in serial experiments in single animals. Independent verification of K1 values was obtained with quantitative autoradiographic measurements of α-aminoisobutyric acid, which has similar physicochemical properties to meglumine iothalamate. The CT methodology is capable of demonstrating regional variation of trans-capillary transport in brain tumors and may be of value in the study of human brain tumors.

Intracavernous Carotid Artery Aneurysm Presenting as Recurrent Epistaxis

Massive epistaxis from a leaking intracavernous carotid artery aneurysm is a rare occurrence. Such an unusual case is presented with appropriate imaging and a successful treatment program.

MR Diagnosis of Acoustic Neuromas

Two hundred forty-three patients with clinically suspected acoustic neuroma were evaluated radiologically by CT, and in selected cases CT cisternography and/or magnetic resonance imaging. Fifty-one acoustic neuromas were diagnosed and surgically removed; 36 were large tumors with extracanalicular extension and 15 were strictly intracanalicular small tumors. With routine CT (without and with contrast medium) large and enhancing lesions (36 of 51) were visualized, but small intracanalicular tumors (15 lesions) were missed. The latter were visualized by CT cisternography (seven cases) or MR (eight cases). Magnetic resonance, when used with spin-echo technique using both short as well as long sequences for axial and coronal thin slices (5 mm or smaller), demonstrated all the surgically verified lesions.

Current concepts in neuroradiological diagnosis of acoustic neuromas

Two hundred twenty‐one cases with clinical suspicion of a cerebellopontine angle (CPA) and/or internal auditory canal (IAC) lesions were evaluated in our hospital in the last 2 1/2 years by various radiological modalities. Fifty‐two tumors were diagnosed and surgically removed; 48 were acoustic neuromas (33 large tumors and 15 intracanalicular small tumors) and 4 meningiomas.