Spontaneous intracranial hypotension with deep brain swelling.

Spontaneous intracranial hypotension (SIH) is caused by leakage of CSF, and characterized on MRI by brain sagging, dilatation of veins and dural sinuses, subdural fluid collections and post-contrast enhancement of the thickened dura. A few cases may present a very severe brain sagging through the tentorial notch and swelling of the diencephalic-mesencephalic structures, with absent or scarce subdural collections and post-contrast enhancement. These patients may have surprisingly few neurological signs or may become drowsy and even lapse into coma due to central herniation. We retrospectively examined the diffusion studies obtained in five patients with these MRI findings, in seven patients with SIH without brain swellings and in ten controls. Mean diffusivity was increased in SIH patients with brain swelling in areas draining into the deep venous system, collected by the vein of Galen (vG) and straight sinus (SS). In the hypothesis that central herniation might be responsible for venous stagnation because of impaired flow of the vG into the SS, the vG/SS angle was measured. The angle formed by the vG entering the SS was not altered in patients without brain swelling (group E, 67.8 degrees +/- 10.3 degrees, mean +/- SD, range 49-80 degrees) when compared to controls (group C, 73.3 degrees +/- 12.3 degrees, mean +/- SD, range 56-95 degrees). It was, however, grossly decreased in patients with brain swelling (group D, 40.7 degrees +/- 12.8 degrees, mean +/- SD, range 22-61 degrees), P < 0.001 for comparison with groups E and C. As suggested by previous studies, downward stretching of the vG and narrowing of the vG/SS angle may cause a functional stenosis at the vG-SS junction. We suggest that in the application of the Monro-Kellie doctrine to SIH, the brain volume should not be considered as always invariable.

Methylation of O6-methylguanine DNA methyltransferase and loss of heterozygosity on 19q and/or 17p are overlapping features of secondary glioblastomas with prolonged survival.

PURPOSE: Recent data suggest that methylation of the DNA repair gene O(6)-methylguanine DNA methyltransferase (MGMT), by increasing the chemosensitivity of glioblastoma multiforme, is significantly associated with improved prognosis. Results in contradiction with these findings, however, are present in the literature and the clinical and genetic context framing MGMT methylation is poorly characterized. EXPERIMENTAL DESIGN: To address these issues, we have investigated the MGMT methylation status, clinical and magnetic resonance imaging characteristics, and relevant genetic features (loss of heterozygosity on 17p and 19q, EGFR amplification, and p53 mutations) in a retrospective study on 86 patients affected by glioblastoma multiforme: 72 patients had a clinical history indicating de novo insurgence of the tumor and the remaining 14 were secondary glioblastoma multiforme. RESULTS: MGMT methylation was detected by methylation-specific PCR in 41 of 86 cases (47.7%; Meth+). Progression-free survival and overall survival were significantly longer in Meth+ than in Meth- patients [10 versus 7 months (P=0.003, log-rank test) and 18 versus 14 months (P=0.0003, log-rank test), respectively]. Mixed-nodular enhancement at magnetic resonance imaging was significantly more frequent in Meth+ and secondary glioblastoma multiforme and ring enhancement in Meth- and primary glioblastoma multiforme (P<0.005). MGMT methylation was more present in secondary glioblastoma multiforme (P=0.006) and associated with loss of heterozygosity on 17p and/or 19q (P=0.005). CONCLUSIONS: These observations suggest that MGMT methylation is part of a genetic signature of glioblastomas that developed from lower-grade gliomas.

Dural sinus thrombosis in spontaneous intracranial hypotension: Hypotheses on possible mechanisms.

Dural sinus thrombosis (DST) is rarely associated with spontaneous intracranial hypotension (SIH). Engorgement of the venous system, caused by the CSF loss that occurs in SIH, is considered to favour the thrombosis, although signs of both SIH and DST are usually seen simultaneously at the first diagnostic MRI. We observed two patients with SIH and DST. Changes in pattern of headaches and MRI findings demonstrated that DST followed SIH. In SIH, the velocity of the blood flow in the dural sinuses may be reduced because of dilatation of the venous system which compensates the CSF loss. Other possible mechanisms seem unlikely on the grounds of both clinical presentation and MRI studies.

Reclassification of oligoastrocytomas by loss of heterozygosity studies.

Oligoastrocytomas (OAs) are WHO grade II or III tumors composed of a mixture of 2 neoplastic cell types morphologically resembling the cells in oligodendrogliomas and diffuse astrocytomas. Investigations on the genetic profile of OAs may yield important information for their classification and help for their clinical management. We have studied, in 94 OAs (46 WHO grade II and 48 WHO grade III), the patterns of loss of heterozygosity (LOH) of 4 genomic regions: 1p, 19q, 17p and 10q. Results were as follows: LOH 1p was present in 46% of the tumors; LOH 19q in 45%; LOH 17p in 22%; LOH 10q in 16%. LOH 1p and 19q were associated in 32%, other LOH associations were rare (<3%). Patients had a median follow-up of 30 months. Patients without LOH on 1p had shorter progression free survival than patients with LOH on 1p: 30 vs. 132 months, p < 0.0001. MRI indicated that tumors without LOH on 1p were often temporal (p < 0.02), and showed signal inhomogeneity on T1 and T2 images (p < 0.02) and contrast enhancement (p < 0.04). Thus, LOH on 1p identifies two subgroups of OAs. OAs without LOH on 1p behave like WHO grade II or III diffuse astrocytomas: they have shorter survival, MRI characteristics implying malignancy and genetic alterations associated with tumor progression. OAs with LOH on 1p, on the other hand, behave like WHO grade II or III oligodendrogliomas with 1p loss: they are associated with longer survival and do not have MRI or genetic alterations associated with malignancy. These findings suggest that the definition of OAs or mixed gliomas could be reshaped in agreement with the genetic information.

Wallerian degeneration of the pontocerebellar fibers.

Two cases of pontine infarct with Wallerian degeneration (WD) of the pontocerebellar fibers are described. WD of pontocerebellar fibers, seen bilaterally along the transverse pontine fibers, is more visible in the middle cerebellar peduncles and extends into the white matter of the cerebellar hemispheres. Understanding the anatomy of the white matter and the temporal evolution of this degeneration is essential in identifying WD.

Spontaneous partial thrombosis of a basilar artery giant aneurysm in a child.

We report the complete, spontaneous obliteration of a partially thrombosed dissecting giant aneurysm in the basilar artery by occlusion of both the lumen of the aneurysm and the parent artery in a 15-year-old girl.

Breast MRI screening in patients with increased familial and/or genetic risk for breast cancer: a preliminary experience.

AIMS AND BACKGROUND: Breast cancer is the most common cancer affecting women, and it is associated with or due to a genetic predisposition in 5%-10% of the cases. Owing to the higher risk of developing breast cancer and the early onset of the disease in women proved or suspected to be carriers of a breast cancer susceptibility gene, a dedicated screening should be offered as a less invasive approach with the otherwise suggested prophylactic mastectomy. This should be optimized in order to overcome the limitations of conventional breast imaging with the application of new technologies such as breast magnetic resonance imaging. METHODS: A diagnostic protocol for routine control in patients at high risk of developing breast cancer has been prepared. Within a 7-month period, 23 patients suspected or proved to carry a breast cancer susceptibility gene underwent breast magnetic resonance imaging. RESULTS: Four breast cancers were identified with breast magnetic resonance imaging. In these cases, mammography was negative because of the density of the parenchyma or for its fibroglandular pattern. Ultrasound was negative in 2 cases, not specific for malignancy in 1 case, and considered as only possibly malignant but with biopsy recommendation on the basis of magnetic resonance findings in the last one. Clinical analysis was positive for a mass in 2 cases. CONCLUSIONS: The accuracy of breast magnetic resonance imaging is known to be higher than that of conventional imaging in the study of breast parenchyma. High spatial resolution, no breast density influence and multiplanarity can give more detailed information about the smaller lesions and the right extension of the disease. Preliminary studies where breast magnetic resonance imaging is performed in addition to mammography within this group of patients are encouraging. We also believe that the application of breast magnetic resonance imaging can be very useful in the detection of cancer as early as possible with the aim to obtain the highest chance of survival after treatment.

Breast microcalcifications studied with 3D contrast-enhanced high-field magnetic resonance imaging: more accuracy in the diagnosis of breast cancer.

AIMS: To evaluate the reliability of magnetic resonance imaging (MRI) performed with three-dimensional (3D) sequences in mammographically detected breast microcalcifications. METHODS: During an 8-month period, a group of 28 patients with mammographically detected microcalcifications suspicious for malignancy underwent MRI. Their ages ranged from 33 to 65 years. Examinations were performed with a 1.5 Tesia MR unit and a 3D T1 weighted sequence. Images were interpreted on the basis of morphologic parameters and dynamic behavior in the uptake of contrast medium (Gd-DTPA). Histologic findings were considered as the gold reference. RESULTS: Histologic analysis revealed invasive carcinoma in 7 patients, 3 of which were associated with foci of lobular carcinoma in situ. Intraductal carcinoma was diagnosed in 8 patients, 1 of which was associated with a tubular carcinoma. Benign lesions accounted for 13 patients. All the neoplastic conditions showed enhancement on MR images (sensitivity, 100%), whereas early and intense enhancement was noted in 5 of 13 benign lesions (specificity, 61%). The positive predictive value was 75% and negative predictive value, 100%. CONCLUSIONS: Although an overlap in the enhancement behavior of malignant and some benign lesions is clearly evident, a careful interpretation of MR images is helpful in detecting and mainly ruling out breast cancer combined with mammographically suspicious microcalcifications.