Correlation of neuropathologic findings, computerized tomographic and high-resolution ultrasound scans of canine avian sarcoma virus-induced brain tumors

Abstract

The location, size, geometry and neuropathological findings of anaplastic astrocytomas (AA), gliosarcomas and sarcomas induced by the avian sarcoma virus (ASV) in dogs were compared with images generated using computerized tomography (CT) and real time high-resolution ultrasound (HRUS). Seven AA showed a wide range of findings on CT. Pre-contrast CT scans showed that the tumors could be hyper, hypo, or isodense. Three of seven AA had no contrast enhancement; two of these tumors were also isodense which resulted in a false-negative CT exam. Partial enhancement was seen in one tumor. This resulted in a sensitivity of detection of 72%. Real time HRUS was able to define tumor location, size and geometry of the AA missed or incompletely imaged by CT. All tumors were hyperechoic. Inhomogeneity of the echo pattern was due to hemorrhage, cyst formation, and necrosis within the tumors. Such secondary tumor characteristics were more accurately defined by HRUS compared to CT. Vasogenic edema in the brain surrounding tumors was of low density on CT and hypoechoic or indistinguishable from normal brain on US. Similar findings were seen in six gliosarcomas, two of which were not visualized by either pre- or post-contrast enhanced CT scans (sensitivity of 66%). Sarcomas differed in that they were either hyper or isodense; none were hypodense. The area of increased density matched the tumor geometry and correlated with dense cellularity and reticulin deposition. All 13 sarcomas showed contrast enhancement (100% sensitivity), but in two tumors, contrast enhanced CT underestimated the size of the tumor. Because of the large size and multiplicity of the sarcomas, HRUS imaging was not able to resolve the entire tumor volume because of limited imaging access. Intravenously injected horseradish peroxidase (HRP) crossed the tumor blood-brain barrier (BBB) only in those tumors in which contrast enhancement was seen. These studies suggest that intraoperative HRUS imaging may be useful in detecting and delineating human AA incompletely visualized by CT.

Correlation of intra-operative ultrasound with histopathologic findings after tumour resection in supratentorial gliomas

“…Ultrasound has shown intra-operatively [5,8,11,15,22,26,30,32,48,50,59,61,62,64,66,73,76,79,81] and transcranially [6,9,10,17,69,75,77] to be a reliable real-time method in the delineation of tumour tissue before resection, even superior to contrast-enhanced CT or MRI [35,43,47].…”

Immunohistochemical study of glial fibrillary acidic protein in avian sarcoma virus-induced gliomas in dogs

“…The usefulness of this large animal glioma model is being increasingly appreciated. ASV-induced canine brain tumors 57 have been recently used for studies of the histopathological basis of brain tumor imaging using computed tomography (9, 23) and high-resolution ultrasound imaging (9), and for evaluating the nature of histopathological changes following intratumoral interstitial irradiation (34).…”

“…Growth of tumors was monitored by computerized tomographic (CT) and high resolution ultrasound scans using techniques described elsewhere (9). At the appropriate time, animals were anesthetized and perfused with 10% buffered formalin solution and the brains were removed.…”

Spectral image reconstruction for transcranial ultrasound measurement

“…However, methods such as tomographic reconstructions have been explored (Dines et al 1981, Koivukangas et al 1986, Britt et al 1987, and recent feasibility studies have examined improved imaging techniques such as perfusion imaging (Wiesmann and Seidel 2000, Harrer et al 2003) and real-time 3-D imaging (Smith et al 2004) for volumetric time histories in the brain. There has also been an effort to propagate ultrasound through a larger region of bone, including thicker and more complex regions (Baikov et al 2003b, Baikov et al 2003a, in order to expand the quality and volume of the brain volume to be imaged.…”

“…Although it has long been recognized that transcranial ultrasound holds the potential for detecting an extensive range of brain disorders (Wall et al 1953, Barrows et al 1964, Grossman 1964, Fry 1968, Erikson et al 1974, Smith et al 1978, 1979, strong attenuation and distortion by the skull bone has limited its practical clinical use to Doppler imaging through the temporal bone window (Berg and Becker 2002) for injury detection (Shigemori et al 1990) and tumour detection (Becker et al 1994). However, methods such as tomographic reconstructions have been explored (Dines et al 1981, Koivukangas et al 1986, Britt et al 1987, and recent feasibility studies have examined improved imaging techniques such as perfusion imaging (Wiesmann and Seidel 2000, Seidel et al 2000, Harrer et al 2003 and real-time 3D imaging (Smith et al 2004) for volumetric time histories in the brain. There has also been an effort to propagate ultrasound through a larger region of bone, including thicker and more complex regions (Baikov et al 2003a(Baikov et al , 2003b, in order to expand the quality and volume of the brain volume to be imaged.…”