Contrast Media Enhancement of Intracranial Lesions in Magnetic Resonance Imaging Does Not Reflect Histopathologic Findings Consistently

Abstract

Certain magnetic resonance (MR) enhancement patterns are often considered to be associated with a specific diagnosis but experience shows that this association is not always consistent. Therefore, it is not clear how reliably contrast enhancement patterns correlate with specific tissue changes. We investigated the detailed histomorphologic findings of intracranial lesions in relation to Gadodiamide contrast enhancement in 55 lesions from 55 patients, nine cats, and 46 dogs. Lesions were divided into areas according to their contrast enhancement; therefore 81 areas resulted from the 55 lesions which were directly compared with histopathology. In 40 of 55 lesions (73%), the histomorphologic features explained the contrast enhancement pattern. In particular, vascular proliferation and dilated vessels occurred significantly more often in areas with enhancement than in areas without enhancement (P = 0.044). In 15 lesions, there was no association between MR images and histologic findings. In particular, contrast enhancement was found within necrotic areas (10 areas) and ring enhancement was seen in lesions without central necrosis (five lesions). These findings imply that necrosis cannot be differentiated reliably from viable tissue based on postcontrast images. Diffusion of contrast medium within lesions and time delays after contrast medium administration probably play important roles in the presence and patterns of contrast enhancement. Thus, histologic features of lesions cannot be predicted solely by contrast enhancement patterns.

Unique Topographic Distribution of Greyhound Nonsuppurative Meningoencephalitis

“…A similar disconnect has been found in granulomatous meningoencephalitis in which meningitis was not seen on MR images despite histological evidence of meningeal disease . Therefore, contrast enhancement of intracranial lesions does not reflect histopathologic findings consistently, and histologic features of lesions cannot be predicted solely by contrast enhancement patterns …”

“…23 Therefore, contrast enhancement of intracranial lesions does not reflect histopathologic findings consistently, and histologic features of lesions cannot be predicted solely by contrast enhancement patterns. 24 The distribution of image changes was similar in all four dogs, with a predilection for the rostroventral parts of the cerebrum, especially the olfactory lobes. The consistent involvement of the olfactory lobe is different from other nonsuppurative meningoencephalitides in which no olfactory involvement has been reported, suggesting unique topographic predilection (Figs.…”

Advances in Diagnostic and Treatment Modalities for Intracranial Tumors

“…Although many investigators have attempted to utilize a variety of imaging techniques to diagnose, and even grade, intracranial lesions in dogs, specificity, sensitivity, or both have been shown to be consistently suboptimal in numerous studies,12, 15, 16, 36, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56 particularly when applied to clinically relevant prospective random populations of patients. A majority of intracranial tumors in both dogs and cats are hypo‐ to isointense on T1‐weighted imaging, and hyperintense on T2‐weighted imaging.…”

“…Large cystic structures may be associated with many tumor types, but they occur most commonly with meningiomas where their frequency is approximately 25% 15. Presence of “dural tails” and ring enhancement patterns on postcontrast T1‐weighted images has been associated with meningiomas and gliomas, respectively, but studies suggest that these patterns may be seen in a wide variety of intracranial diseases 53, 56, 59. Realistically, many therapeutic decisions are made based on presumptive imaging‐based data, but the limitations of these data and the consequences in individual animals should not be overlooked.…”

Evaluation of Standard Magnetic Resonance Characteristics Used to Differentiate Neoplastic, Inflammatory, and Vascular Brain Lesions in Dogs

“…Familiarity with the histologic behavior of diseases may aid in MR interpretation . However, histopathological lesions are not reliably reflected in MR findings, and variability of MR signal intensity or contrast enhancement can be seen with neuronal loss, vascular damage, perilesional edema, and necrosis …”