Fast FLAIR images have noticeable T1 contrast making gadolinium-induced enhancement visible. Gadolinium enhancement in lesions that are hyperintense on precontrast FLAIR images, such as intraparenchymal tumors, may be better seen on T1-weighted images than on postcontrast fast FLAIR images. However, postcontrast fast FLAIR images may be useful for detecting superficial abnormalities, such as meningeal disease, because they do not demonstrate contrast enhancement of vessels with slow flow as do T1-weighted images.

Multisection computed tomography (CT) was introduced in 1992 with the advent of dual-section-capable scanners and was improved in 1998 following the development of quad-section technology. With a recent increase in gantry speed from one to two revolutions per second, multisection CT scanners are now up to eight times faster than conventional single-section helical CT scanners. The benefits of quad-section CT relative to single-section helical CT are considerable. They include improved temporal resolution, improved spatial resolution in the z axis, increased concentration of intravascular contrast material, decreased image noise, efficient x-ray tube use, and longer anatomic coverage. These factors substantially increase the diagnostic accuracy of the examination. The multisection CT technique has enabled faster and superior evaluation of patients across a wide spectrum of clinical indications. These include isotropic viewing, musculoskeletal applications, use of multiplanar reformation in special situations, CT myelography, long coverage and multiphase studies, CT angiography, cardiac scoring, evaluation of brain perfusion, imaging of large patients, evaluation of acute chest pain or dyspnea, virtual endoscopy, and thin-section scanning with retrospective image fusing. Multisection CT is superior to single-section helical CT for nearly all clinical applications.

Perineural spread of head and neck tumors is a form of metastatic disease in which tumor disseminates to noncontiguous regions along the endoneurium or perineurium. Both computed tomography (CT) and magnetic resonance (MR) imaging can help detect perineural spread, although MR imaging is the modality of choice because of its multiplanar capability, its superior soft-tissue contrast, and the decreased amount of artifact from dental hardware. Perineural spread most commonly occurs in adenoid cystic carcinoma and squamous cell carcinoma. Nerve enlargement may lead to foraminal enlargement and, ultimately, to foraminal destruction, findings that are best seen at CT. Extension through the foramen ovale and involvement of the Meckel cave is best seen on coronal T1-weighted MR images, and nerve enhancement is best seen on fat-suppressed T1-weighted MR images. Other radiologic findings include obliteration of fat planes at foraminal openings, neuropathic atrophy, cavernous sinus enlargement, and replacement of the trigeminal subarachnoid cistern with soft tissue. The pathway of perineural tumor spread is predictable with knowledge of the pertinent cranial nerve anatomy; however, patients with radiologically or pathologically proved perineural spread may have normal nerve function at clinical examination. Therefore, it is imperative that the radiologist be familiar with both normal cranial nerve anatomy and the radiologic appearance and assessment of perineural tumor extension.

A retrospective analysis of CT and MRI studies in 12 patients with a clinical diagnosis of acute disseminated encephalomyelitis (ADEM) was performed. MRI was the definitive modality for the assessment of the lesions of ADEM: all patients had abnormalities consistent with the clinical diagnosis. Ten had abnormalities in the brain, three spinal cord lesions, and three showed evidence of optic neuritis. CT was normal in 6 of the 7 patients in which it was performed.

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OBJECTIVE. The purpose of thisstudywasto evaluate thefeasibilityof administeringtopical contrast material during helical CT dacryocystography and topical saline solution dur ing MR dacryocystography to reveal the lacrimal drainage apparatus. SUBJECTS AND METHODS. Fourteenhealthyvolunteers underwent helicalCTdacryocystography, MR dacryocystography, or both. Eight of the 14 subjects underwent both techniques; three subjects underwent MR dacryocystography, and three subjects underwent CT dacryocystography. Images were evaluated by two radiologists for degree of visualization of componentsof the lacrimal drainageapparatus. Each volunteerwas questionedaboutthe relativediscomfortof contrastmaterialandsalinesolutionadministration.

Background Ultrasound of the neck with fine needle aspiration (US‐FNA) of suspicious lymph nodes has potential advantages over other radiologic techniques as a screening method for the N0 neck in head and neck cancer. Methods Twenty‐five patients with head and neck cancer who underwent both US of the neck with FNA of any suspicious lymph nodes and neck computed tomography (CT) prior to elective neck dissection were studied. The majority of patients had squamous cell carcinoma (SCC) of the upper aerodigestive tract. Histopathologic results of the neck specimens were compared with each screening technique (palpation, US, US‐FNA, CT). Results Computed tomography (87.9%) and US‐FNA (84.9%) had similar overall accuracy in terms of screening the N0 neck in our study and were superior to palpation (69.7%) and US alone (72.7%). Specificity was 100% for both CT and US‐FNA, with a sensitivity of 60% for CT and 50% for US‐FNA. Ultrasound‐FNA and CT showed false‐negative examinations on virtually the same cases. Conclusions Overall, US‐FNA was comparable to CT in screening the N0 neck in our study. The choice of which modality to employ for imaging the clinically negative neck depends on a number of factors, including the location and clinical extent of the primary tumor as well as the experience and preference of the head and neck surgeon and radiologist. © 1997 John Wiley & Sons, Inc. Head Neck 19: 604–610, 1997.