Reduction of aneurysm clip artifacts on CT angiograms: a technical note.

We describe a head tilt technique for use with CT angiography that reduces beam-hardening artifacts in patients with aneurysm clips. This simple maneuver directs the artifacts away from pertinent anatomy, thus increasing the chances for diagnostic accuracy. No significant changes in the CT angiographic protocol are required, and the maneuver can easily be combined with other artifact-minimizing strategies.

Exercise-related dissection of craniocervical arteries: CT, MR, and angiographic findings.

OBJECTIVE: Our goal was to demonstrate the spectrum of neuroradiologic (CT, MR, and angiographic) findings in craniocervical arterial dissection (CAD) related to exercise or sporting activities and compare the diagnostic utility of CT, MRI, and MR angiography (MRA). MATERIALS AND METHODS: The neuroradiologic examinations of 11 patients with CAD was performed: CT was performed in 10 patients, cranial MRI in 9, cranial and cervical MRA in 4, and contrast angiography in 10. The CT examinations were assessed for the presence of an infarction or a hyperdense artery (consistent with intraluminal thrombus), MRI examinations for the presence of infarction or abnormal periarterial signal, and contrast angiograms for arterial stenosis or occlusion, luminal irregularity, pseudoaneurysm, intimal flap, or distal branch occlusions. RESULTS: Computed tomography demonstrated infarction in four patients. At contrast angiography, a dissection was found in the artery supplying the region of infarction in all cases. A hyperdense artery was found by CT in two patients, which correlated with dissection of the artery or its parent artery on contrast angiography. Cranial MRI findings were seen in six patients (infarction in five, periarterial signal abnormality in five). Dissection was confirmed in all four patients with abnormal periarterial signal who underwent contrast angiography. Two patients with abnormal intracranial periarterial signal had corresponding abnormalities on MRA. False-negative cranial and cervical MRI and MRA studies were performed in one patient because the imaging volumes used for the cervical and intracranial MR examinations did not overlap. Four patients with normal intracranial arterial signal had dissection in the neck demonstrated by contrast angiography. CONCLUSION: Neuroradiologic findings of CAD can include infarction, a hyperdense artery on CT, abnormal periarterial signal on MRI, and a narrowed arterial signal column on MRA. Computed tomography is an insensitive screening examination. Proper use of MRI and MRA involves examination of both the head and the neck with overlapping imaging volumes of the two regions.

Internal carotid artery dissection associated with pituitary apoplexy: MR findings.

Pituitary apoplexy almost invariably occurs following hemorrhage into a pituitary neoplasm. We report a case in which pituitary apoplexy occurred in the setting of, and probably secondary to, dissection of the internal carotid artery.

Apparent culture-negative endocarditis of the prosthetic valve caused by Cardiobacterium hominis.

To date, there have been fewer than 50 reported cases of endocarditis caused by C hominis. Only six of these involved prosthetic heart valves. To our knowledge, in no previous case has the organism been cultured directly from the valve, an aspect we believe gives our case special relevance. Our case also illustrates the fact that whenever a fastidious organism is thought to be responsible for infective endocarditis, not only blood cultures but also cardiac tissue cultures should be held beyond the customary period of time.

Tension fecal pneumothorax in a postpartum patient.

A 20-year-old woman developed severe shortness of breath 4 h after a cesarean section. Chest roentgenogram showed a pleural effusion and tension pneumothorax; insertion of a chest tube drained liquid stool. At surgery she was found to have a left diaphragmatic defect with herniation, strangulation, and perforation of the transverse colon into the pleural cavity.

Past, present, and future of radiology of meningioma.

The evolution of the radiologic findings associated with meningiomas represents a microcosm of the evolution of diagnostic radiology that has occurred since the discovery by Röntgen of the x-ray beam in 1895 and the founding of the Radiological Society of North America in 1915. What will the next new, as yet unimagined, imaging modality contribute to our current ability to detect and diagnose these lesions? No one can forecast this, but it should prove to be both fascinating and challenging.

Abnormal corpus callosum: a sensitive and specific indicator of multiple sclerosis.

The authors investigated whether identification of corpus callosal (CC) involvement might increase the specificity of magnetic resonance (MR) imaging in differentiating multiple sclerosis (MS) from other periventricular white matter diseases (PWDs). They prospectively evaluated 42 patients with MS and 127 control patients with other PWDs. Ninety-three percent of the MS patients demonstrated confluent and/or focal lesions involving the callosal-septal interface (CSI). These lesions characteristically involved the inferior aspect of the callosum and radiated from the ventricular surface into the overlying callosum. CSI lesions were optimally demonstrated on sagittal long repetition time (TR)/short echo time (TE) images and frequently (45% of cases) went undetected on axial images. Only 2.4% of the control patients had lesions of the CC. The authors conclude that midsagittal long TR/short TE images are highly sensitive and specific for MS and that callosal involvement in MS is more common than previously reported.

Wallerian degeneration after cerebral infarction: evaluation with sequential MR imaging.

The dynamic signal intensity changes at magnetic resonance (MR) imaging in active and chronic wallerian degeneration in the corticospinal tract were evaluated. Forty-three patients with wallerian degeneration seen on MR images after cerebral infarction were studied. When possible, patients with acute stroke were examined with MR imaging prospectively at the onset of symptoms and then at weekly intervals for several months. Focal infarction without distal axonal degeneration is demonstrated for the 1st month following onset of clinical symptoms. At 4 weeks, a well-defined band of hypointense signal appears on T2-weighted images in the topographic distribution of the corticospinal tract. After 10-14 weeks, the signal becomes permanently hyperintense. Over several years, accompanying ipsilateral brain stem shrinkage occurs. The dark signal intensity observed on T2-weighted images between 4 and 14 weeks is believed to result primarily from transitory increased lipid-protein ratio.