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T1-weighted magnetic resonance images (T1WI) of the head may manifest high signal in many normal and pathologic situations. Normally, it may be seen in fatty tissues, certain artifacts, and in areas without a blood-brain barrier after gadolinium administration. It is also seen in the posterior pituitary gland and in certain instances in the anterior pituitary gland. Pathologically, it may occur in many lesions after gadolinium enhancement, in fatty and cystic lesions, and in lesions with paramagnetic content. Occasionally, it may be seen in calcium deposition. Many of these are described and illustrated.

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The anterior pituitary gland may exhibit high signal on T1-weighted (T1w) images and/or low signal on T2-weighted (T2w) images in several normal and pathological states. High T1w signal may be seen in normal fetuses, neonates, and in pregnant and postpartum women. It may also occur in Rathke's cleft cyst, craniopharyngioma, subacute hemorrhage, manganese deposition, melanoma, dermoid, and lipoma. Low T2w signal may be seen in hemorrhage, calcification, cystic lesion, hemochromatosis, melanoma, and vascular lesions. These are described and illustrated.

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A 53-year-old woman with a long history of compulsive nose picking (rhinotillexomania) presented with a large, self-inflicted nasal septal perforation and right-sided penetration of the ethmoidal sinus, or "ethmoidectomy."

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Forty-eight patients had 50 extraforaminal disk herniations (EFDHs) demonstrated on CT and/or MR by (1) presence of disk density or disk signal material lateral to the neural foramen, (2) displacement or obliteration of paravertebral fat, and (3) nerve root or ganglion compression or displacement. Forty-one of 50 EFDHs had a coexisting intraforaminal component; nine of 50 had an isolated far lateral herniated nucleus pulposus. EFDHs typically occurred in the absence of a coexisting intraspinal disk herniation. Migratory fragments were seen in 50% of all cases and were at or cephalad to the interspace of origin in all cases. Forty-six percent of EFDHs were at L2-L3 or L3-L4, although the most commonly affected level was L4-L5 (38%). EFDHs, which were often overlooked (15/50 scans reviewed), are an important preventable cause of failed intraspinal diskectomy. EFDHs can be readily identified on both CT and MR if appropriate scans are obtained from L2 through S1 and if the neural foramina and paravertebral spaces are carefully examined.

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The computed tomographic appearances of 22 biopsy-proved supratentorial ependymomas were analyzed. Supratentorial ependymomas were usually intraparenchymal, larger than 4 cm, and cystic. Contrast enhancement was moderate to intense, with homogeneous or ring-enhancement patterns commonly seen. Intratumoral calcification was present in one-third of the cases, while hydrocephalus and peritumoral edema were seen in 50%. Intratumoral hemorrhage was not a characteristic of the lesion. In contrast to cellular ependymomas, malignant ependymomas and ependymoblastomas demonstrate higher attenuation prior to administration of contrast material, more intense enhancement, lower frequency of calcification within the tumor, and less distinct margination.

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A preliminary study showed that encouraging laboratory results reported previously using tomographic digital subtraction angiography (DSA) can be transferred to clinical application for neurovascular imaging. Tomography may show cervical carotid disease more clearly than standard DSA images, and it eliminates the interference caused by overlapping vessels. Production of multiple tomographic image planes from a single set of projection data, tomosynthesis, must be incorporated into this imaging system before tomographic DSA becomes clinically useful. This is a practical reality with the present equipment; clinical evaluation of this new capability is underway.

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Improved visualization of the initial bolus of contrast material injected via a lateral Cl-2 puncture for cervical myelography can be obtained by using real-time digital subtraction fluoroscopy. As little as 0.1 ml of metrizamide (250 mg%) can be demonstrated easily.

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Procedural control during therapeutic neuroradiologic procedures is generally based on repeated angiograms to assess the degree to which embolization has reduced abnormal blood flow. Due to the complex craniofacial skeletal anatomy that is superimposed over lesions in this area, subtraction studies are usually required to see the vessels and visualize a tumor stain satisfactorily. We have used a device incorporating continuous recursive digital video filtration, which allows the operator to view a subtracted fluoroscopic image of each control angiographic sequence in real time. The advantages of this technique for therapeutic procedures are described.

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Deformities of the margins of the contrast material-filled lumbar thecal sac are common findings at myelography in patients with low back pain, but not all such deformities are due to herniated disks. Differentiation at Amipaque myelography between a diffusely bulging disk (unlikely to cause nerve root compression) and a herniated disk (which typically causes nerve root compression) is based on the curvature and extent of the extradural deformity of the anterolateral margin of the contrast-filled sac and on the presence of fusiform widening of the most distal part of the affected nerve root. The deformity caused by a bulging disk is rounded, usually symmetrical (although occasionally more prominent on one side), and does not extend above or below the disk space; the nerve root is uniform in caliber and normal in size. The deformity caused by a herniated disk is angular and extends cephalad and/or caudal to the level of the disk space; the affected nerve root is usually widened in its most distal visible part. A consecutive series of 33 patients with clinically suspected lumbar disk herniation and no previous history of back surgery underwent laminectomy. Using the criteria listed above for differentiation of bulging from herniated disk on Amipaque myelography, the myelographic diagnosis was correct in all six operatively confirmed bulging disks and in 26 (96%) of 27 operatively verified disk herniations.

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To assess the value of computed tomography in degenerative lumbar spinal stenosis, postoperative computed tomography was compared to preoperative studies and other radiographic modalities in 20 patients, ten with an excellent surgical result and ten with a poor result. A close correlation was found between moderate to severe residual stenosis on postoperative CT and surgical failure. The most common cause of failure was inadequate unroofing of the lateral gutters. Computed tomography with multiplanar reconstructions detected stenosis not only in the central canal and lateral recesses, but in the neuroforaminal as well. Central canal stenosis corresponded to a marked deformity of complete block on myelography. Lateral recess stenosis was shown more often by computed tomography than by blunting of the nerve root sheaths on the myelograms. Neuroforaminal encroachment seen on computed tomography sagittal reconstructions was not demonstrable by myelography. Degenerative spondylolisthesis, a special stenotic condition, produced a characteristic "double margin" sign on computed tomography and the critical stenosis of the lateral recesses was demonstrated. This study suggests that the superior definition of the sites of degenerative spinal stenosis provided by computed tomography should lead to higher surgical success rates.

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Current methods of staging bladder carcinoma have many disadvantages. A new method of staging bladder tumors employing computed tomography (CT) of the gas-filled bladder is presented. Representative cases are demonstrated. Direct visualization of the extent of the tumor and adjacent soft tissue structures is possible. CT scanning of the gas-filled bladder is a promising new method for staging bladder tumors and following their response to therapy.

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