Advanced Neuroimaging in the Evaluation of Spinal Cord Tumors and Tumor Mimics: Diffusion Tensor and Perfusion-Weighted Imaging.

Spinal cord tumors are an important component of pathologic diseases involving the spinal cord. Conventional magnetic resonance (MR) imaging only provides anatomical information. MR diffusion tensor imaging (DTI) and MR perfusion-weighted imaging (PWI) may detect microstructure diffusion and hemodynamic changes in these tumors. We review recent application studies of MR DTI and PWI in spinal cord tumors. Overall, MR DTI and MR PWI are promising imaging tools that are especially useful in improving differential diagnosis between spinal cord tumors and tumor mimics, preoperative evaluation of resectability, and providing assistance in surgical navigation.

MR perfusion-weighted imaging may help in differentiating between nonenhancing gliomas and nonneoplastic lesions in the cervicomedullary junction.

PURPOSE: To evaluate the ability of dynamic susceptibility-weighted contrast-enhanced magnetic resonance (MR) perfusion imaging (DSC-PWI) in distinguishing between nonenhancing gliomas and nonenhancing, nonneoplastic lesions in the cervicomedullary junction region. MATERIALS AND METHODS: This retrospective study involved eight patients with nonenhancing gliomas in the medulla oblongata and eight patients with nonenhancing nonneoplastic lesions. The relative cerebral blood volume (rCBV) ratios, peak heights, and percentage of signal intensity recovery derived from time-signal intensity curves of these nonenhancing lesions were compared. RESULTS: The mean peak height of nonenhancing gliomas was significantly higher than the value of their reference regions of interest (ROIs). In contrast, mean peak height of nonneoplastic lesions was significantly lower than their reference ROIs. The mean peak height and mean maximal rCBV ratio of nonenhancing gliomas were significantly higher than those of nonenhancing, nonneoplastic lesions (P<0.05). There was no significant difference with regard to percentage of signal intensity recovery between the two groups. CONCLUSION: DSC-PWI could be a useful adjuvant tool to differentiate between nonenhancing gliomas and nonenhancing, nonneoplastic lesions in the cervicomedullary junction region.

A subset of breast cancer predisposes to brain metastasis.

This study evaluated the expression of biological markers of breast cancers with brain metastases. Eighteen paired tumors were assessed, with 42 non-brain-metastasizing breast cancers that were stained with ER, PR, HER2, CK5/6, p63, and Ki67, and were also classified into intrinsic subtypes. The expression patterns between the breast tumors with brain metastases were compared to the brain metastases and the controls. Breast cancers with brain metastases were of higher grade and showed higher incidence of lymph node metastases at initial diagnosis and higher EGFR, p63, and Ki67 expression. In the group of breast cancers with brain metastases, the brain metastases showed higher HER2, CK5/6, and Ki67 expression compared to the breast primaries. There was also a higher incidence of basal subtype and a lower incidence of luminal subtype. When tumors metastasized, changes in hormonal receptor (22%) and HER2 (6%) status were observed. We concluded that breast cancers with higher grade, lymph node involvement at diagnosis, high EGFR, p63, and Ki67 expression, and of basal subtype were at higher risk for brain metastases, and that both hormonal receptors and HER2 status may change in brain metastases.

A case of cervical spinal cord glioblastoma diagnosed with MR diffusion tensor and perfusion imaging.

Intramedullary glioblastomas in adult patients have rarely been reported. We describe magnetic resonance (MR) imaging findings, include findings on diffusion tensor imaging (DTI) and dynamic susceptibility contrast perfusion weighted imaging (PWI) in a case of autopsy-confirmed glioblastoma in a 72-year-old man. Serial MR examinations, DTI and PWI, and positron emission tomography examinations were performed. The tumor involved the medulla oblongata and the upper cervical spinal cord. Traditional MR imaging findings were unclear with regard to the differential diagnosis between intramedullary glioma or a tumefactive demyelinating lesion, but an increase in regional cerebral blood volume and a decrease in fractional anisotropy of the lesion correctly suggested a high-grade glioma. MR PWI and DTI may prove helpful to diagnose glioblastoma of the cervical cord when other imaging features are inconclusive.

N-Acetyl peak in MR spectra of intracranial metastatic mucinous adenocarcinomas.

Absence of N-acetylaspartate (NAA) is one important diagnostic criterion of MR spectroscopy (MRS) that may suggest that an intracranial mass lesion is a metastasis. We report two cases of histopathology-confirmed intracranial metastatic mucinous adenocarcinoma, which predominantly showed a large metabolite peak at 2.0 ppm, mimicking an NAA peak of normal brain tissue. This finding could be of help in the interpretation of MRS in cases of intracranial enhancing mass lesions, metastases or gliomas.

56-year-old male with left-sided weakness.

A 56-year-old male with a 3-year history of multiple myeloma that was treated with tandem autologous stem cell transplantations. He presented in July 2006 with a left partial hemiparesis and ataxia. MRI of the brain revealed an enhancing large right frontoparietal lesion with heterogeneously hyperintense nodular septations on T2WI, with no significant surrounding edema. The differential diagnosis of this lesion placed a high-grade glioma at the top of the list. The patient underwent surgical resection of the lesion. Pathology confirmed the diagnosis of a relapse of his multiple myeloma. The specimen demonstrated a monomorphic neoplasm arranged in sheets and trabeculae floating in a background of a proteinaceous substance. Immunohistochemistry showed the neoplastic cell was a CD138 positive plasma cell. The nature of the background substance is still undetermined and is a very unusual appearance for multiple myeloma. Flow cytometry revealed a monoclonal plasma cell population with an immunophenotype identical to the initial diagnostic bone marrow aspirate. A completely intraparenchymal manifestation of multiple myeloma is rare in itself but the unusual radiographic and histological appearance of this case is extraordinary.

One hundred consecutive hepatic biopsies in the workup of living donors for right lobe liver transplantation.

Living donor liver transplantation allows an increasing number of patients with end-stage liver disease the opportunity for effective treatment in the face of a critical shortage of cadaveric organs. Hepatic steatosis decreases functional graft mass and may contribute to graft dysfunction. Screening liver biopsy allows accurate quantitation of hepatic fat, but is an invasive procedure that is not universally employed in the evaluation of living donors. We studied 100 consecutive prospective right lobe living donors, all evaluated with liver biopsy, imaging studies, and various clinical parameters. The accuracy and predictive value of body mass index (BMI) and imaging were compared with biopsy in determining the amount of hepatic fat. There were no complications to biopsy, with 33% showing some degree of steatosis. BMI correlated only weakly with biopsy, with 73% of overweight (BMI > 25) donors having little or no hepatic fat. Imaging was only 12% sensitive to small amounts (5% to 10%) of fat, with increasing sensitivity to more severe steatosis. Imaging diagnosed steatosis in 2 donors without hepatic fat and failed to identify a candidate denied with biopsy-proven 30% steatosis. Conversely, 9% of candidates with BMIs of 25 or less had 10% or greater steatosis. Moreover, three candidates were denied surgery because biopsy detected occult liver disease. Accurate quantification of hepatic fat is not afforded by BMI and imaging studies alone. Screening liver biopsy has a low complication rate and may serve to increase donor safety. Biopsy is essential in identifying donor grafts at risk for poor recipient outcome while maximizing the donor pool.