Classic signs in head and neck imaging.

Radiologists have long relied upon the use of metaphoric imaging signs to attribute meaning to disease or anatomy-specific imaging patterns encountered in clinical imaging. Teachers of radiology often employ the use of such signs to help learners rapidly identify the typical appearance of various pathologies. Head and neck (H&N) imaging is no exception, and as a specialty that deals with uncommon pathologies and complex anatomy, learners and practising radiologists alike may benefit from this simplistic, pattern-based approach. In this review, we present a compendium of classic imaging signs of H&N lesions, including signs related to traumatic, infectious, neoplastic, congenital, and inflammatory aetiologies found throughout the spectrum of H&N sites (temporal bones, orbits, paranasal sinuses, larynx, salivary glands, and neck soft tissues). Additionally, we identify potential pitfalls and detail critical clinical ramifications related to the rapid and accurate diagnosis of these pathologies.

Intranasal Esthesioneuroblastoma: CT Patterns Aid in Preventing Routine Nasal Polypectomy.

BACKGROUND AND PURPOSE: Esthesioneuroblastoma is a neuroectodermal tumor that commonly arises in the nasal cavity olfactory recess and, when isolated to the intranasal cavity, can be indistinguishable from benign processes. Because lesional aggressiveness requires a more invasive operation for resection than polypectomy, patients with isolated intranasal lesions were studied to define distinguishing CT characteristics. MATERIALS AND METHODS: Patients with intranasal esthesioneuroblastoma and controls without esthesioneuroblastoma with olfactory recess involvement were identified by using a report search tool. Studies demonstrating skull base invasion and/or intracranial extension were excluded. The imaging spectrum of these lesions was reviewed on both CT and MR imaging, and CT findings were compared with those of controls without esthesioneuroblastoma. Two blinded readers assessed subjects with esthesioneuroblastomas and controls without esthesioneuroblastoma and, using only CT criteria, rated their level of suspicion for esthesioneuroblastoma in each case. RESULTS: Eight histologically proved cases of intranasal esthesioneuroblastoma were reviewed. All cases had CT demonstrating 3 main findings: 1) an intranasal polypoid lesion with its epicenter in a unilateral olfactory recess, 2) causing asymmetric olfactory recess widening, and 3) extending to the cribriform plate. Twelve patients with non-esthesioneuroblastoma diseases involving the olfactory recess were used as controls. Using these 3 esthesioneuroblastoma CT criteria, 2 blinded readers evaluating patients with esthesioneuroblastoma and controls had good diagnostic accuracy (area under the curve = 0.85 for reader one, 0.81 for reader 2) for predicting esthesioneuroblastoma. CONCLUSIONS: Esthesioneuroblastoma can present as a well-marginated intranasal lesion that unilaterally widens the olfactory recess. CT patterns can help predict esthesioneuroblastoma, potentially preventing multiple operations by instigating the correct initial operative management.

CT and MR imaging of giant cell granuloma of the craniofacial bones.

BACKGROUND AND PURPOSE: Giant cell granuloma (GCG) is a rare lesion. The purpose of this study was to determine the CT characteristics and describe possible MR imaging features of GCG of the craniofacial bones. METHODS: We retrospectively reviewed 7 CT studies and 1 MR imaging study of 7 histologically proved cases of GCG in 2 men, 3 women, and 2 patients of unknown gender, aged 12-51 years, during a period of 10 years, from 1995 to 2005. RESULTS: The granulomas predominantly involved the maxilla in 3 patients, the mandible in 2 patients, the temporal bone in 1 patient, and the nasal cavity in 1 patient. These lesions on imaging were expansile masses that demonstrated adjacent bone wall thinning, and most were associated with lytic bone destruction. They were predominantly masses with soft-tissue attenuation on CT scans and may have infiltrated the surrounding soft-tissue structures. The patient with an MR imaging had a lesion that was hypointense on both T1- and T2-weighted MR images. The lesions revealed avid homogeneous contrast enhancement. CONCLUSION: The imaging features of GCG are nonspecific. However, this entity should be included in the differential diagnosis of expansile lesions in the craniofacial bones.

The many faces of facial nerve schwannoma.

BACKGROUND AND PURPOSE: The imaging appearance of facial nerve schwannomas (FNSs) has been described as an enhancing tubular mass (using T1-enhanced MR) within an enlarged facial nerve canal (using CT). The purpose of this study is to identify how often the FNS imaging findings conform to this description and determine whether there are underlying anatomic explanations for the discrepant imaging appearances identified. MATERIALS AND METHODS: The clinical, pathologic, and radiologic records of 24 FNS in 23 patients were retrospectively reviewed. Each FNS was evaluated for location along the facial nerve. The lesions were cataloged by facial nerve segment with the imaging characteristics of each segment described. RESULTS: The average age at time of first imaging was 39 years (age range, 10-70 years). Eighteen (71%) of the 24 FNSs were pathologically confirmed, while the others were determined intraoperatively or diagnostically by the presence of both enlargement of the facial nerve canal and enhancement on contrast-enhanced T1 MR examination. The most common location was in the geniculate fossa (83%), followed by the labyrinthine and tympanic segments of the facial nerve (both 54%). The most common clinical presentation was facial neuropathy (42%). CONCLUSION: The classic description of FNS on enhanced T1 MR is that of a well-circumscribed fusiform enhancing mass along the course of the intratemporal facial nerve with bone algorithm CT showing sharply defined bony canal enlargement. Modern imaging techniques, however, demonstrate the importance of the surrounding anatomic landscape, leading to various imaging appearances. Lesions traversing the labyrinthine segment can demonstrate a dumbbell appearance. When FNSs track along the greater superficial petrosal nerve, they may present as a round mass projecting up into the middle cranial fossa. FNS of the tympanic segment of the facial nerve preferentially pedunculate into the middle ear cavity, clinically presenting as a middle ear mass. When the mastoid segment of the facial nerve is involved, irregular and "invasive" tumor margins seen on MR can be explained on CT as tumor breaking into surrounding mastoid air cells.

Imaging and clinical characteristics of temporal bone meningioma.

BACKGROUND AND PURPOSE: Imaging characteristics of temporal bone meningioma have not been previously reported in the literature. CT and MR imaging findings in 13 cases of temporal bone meningioma are reviewed to define specific imaging features. METHODS: A retrospective review of our institutional case archive revealed 13 cases of histologically confirmed temporal bone meningioma. CT and MR imaging studies were reviewed to characterize mass location, vector of spread, bone changes, enhancement characteristics, and intracranial patterns of involvement. Clinical presenting signs and symptoms were correlated with imaging findings. RESULTS: Thirteen temporal bone meningiomas were reviewed in 8 women and 5 men, aged 18-65 years. Meningiomas were stratified into 3 groups on the basis of location and tumor vector of spread. There were 6 tegmen tympani, 5 jugular foramen (JF), and 2 internal auditory canal (IAC) meningiomas. Tegmen tympani and JF meningiomas were characterized by spread to the middle ear cavity. IAC meningiomas, by contrast, spread to the cochlea and vestibule. Hearing loss was the most common clinical presenting feature in all cases of temporal bone meningioma (10/13). The presence of tumor adjacent to the ossicles strongly correlated with conductive hearing loss (7/9). CONCLUSION: Meningioma involving the temporal bone is rare. Three subgroups of meningioma exist in this location: tegmen tympani, JF, and IAC meningioma. Tegmen tympani and JF meningiomas spread to the middle ear cavity. IAC meningiomas spread to intralabyrinthine structures. Conductive hearing loss is commonly seen in these patients and can be surgically correctable.

Absent semicircular canals in CHARGE syndrome: radiologic spectrum of findings.

BACKGROUND AND PURPOSE: This paper describes the CT findings that characterize the middle and inner ear anomalies in coloboma, heart defects, choanal atresia, mental retardation, genitourinary, and ear anomalies (CHARGE) syndrome. With this information, neuroradiologists will be better prepared to provide clinically relevant information to their referring physicians regarding this rare syndrome. MATERIALS AND METHODS: CT studies from 13 patients were reviewed by 2 neuroradiologists with Certificate of Additional Qualification. Each ear was counted separately for a total of 26 ears. Middle and inner ear anomalies associated with CHARGE syndrome were categorized. Investigational review board approval was obtained. RESULTS: Twenty of 26 (77%) ears demonstrated cochlear aperture atresia. Four of these ears were evaluated with MR imaging and were found to lack a cochlear nerve. Twenty-one of 26 (81%) cochlea had some form of dysplasia. Six of 26 (23%) round windows were aplastic. Three of 26 (12%) round windows were hypoplastic. Twenty-one of 26 (81%) oval windows were atretic or aplastic. Fifteen of 26 (58%) vestibules were hypoplastic or dysplastic. There were 5 of 26 (19%) enlarged vestibular aqueducts. Twelve of 26 (46%) vestibular aqueducts had an anomalous course. All cases demonstrated absent semicircular canals. Twenty-three of 26 (88%) facial nerve canals had an anomalous course. Four of 26 (15%) tympanic segments were prolapsed. Three of 26 (12%) temporal bones had an anomalous emissary vein referred to as a petrosquamosal sinus. Twenty-one of 26 (81%) middle ear cavities were small. Twenty-three of 26 (93%) ossicles were dysplastic with ankylosis. Three of 26 (12%) internal auditory canals were small. CONCLUSION: The CT findings that correlate to the anomalies of CHARGE syndrome affect conductive as well as sensorineural hearing. Stenosis of the aperture for the cochlear nerve aperture on CT is suggestive of hypoplasia or absence of the cochlear nerve, which has been demonstrated in some cases by MR. Absence of the cochlear nerve would be a contraindication to cochlear implantation.

Standardization of CT depiction of cochlear implant insertion depth.

BACKGROUND AND PURPOSE: Imaging a cochlear implant with CT is challenging because of implant-induced artifacts, anatomic cochlear variations, and lack of standard terminology for cochlear anatomy. The purposes of this project were to determine whether the cochlear implant tip was more accurately located on oblique CT reformations than on standard images, to review radiology reports for accurate cochlear implant locations, and to assess agreement between an implant surgeon and neuroradiologist by using standardized cochlear anatomy terminology for cochlear implant depth. MATERIALS AND METHODS: In this retrospective study, a neuroradiologist and an implant surgeon independently viewed temporal bone CT images of 36 ears with cochlear implants. Direct axial images, standard coronal reformations, and oblique reformations parallel to the cochlea were compared to determine implant tip location, which was described by using a proposed standardized quadrant terminology. Implant locations were compared with the initial formal report generated by the original interpreting neuroradiologist. RESULTS: Thirty-six temporal bones with cochlear implants underwent CT interpretation for implant location. Interobserver agreement was similar when comparing cochlear implant tip location by using a quadrant nomenclature on axial and coronal images and on oblique reformations. Clinical radiology reports all were imprecise and ambiguous in describing the location of the cochlear implant tip. CONCLUSIONS: Accurate determination of insertion depth of the cochlear implant array can be determined by assessment of the implant tip on axial, coronal, and oblique CT images, but description of the tip location can be inaccurate due to lack of standardized terminology. We propose using a standardized terminology to communicate tip location by using the round window as the zero reference and quadrant numbering to describe cochlear turns. This results in improvement in radiology report accuracy and consistency regarding the cochlear implant insertion depth.

The impact of radiologic imaging on staging of cancer of the head and neck.

CT and MRI are both useful for assessing deep tissue extensions of squamous cell carcinomas of the extracranial head and neck region that are stage T2 or greater. Diagnostic imaging information, in combination with clinical findings, will establish the stage of a primary tumor and the status of regional nodes and will allow a rational treatment plan to be made. Once treatment is completed, a baseline scan 3 to 6 months following treatment is recommended in patients who are at risk for a later recurrence. For most primary tumor sites, MRI will give the most information concerning recurrent disease. Occult primary tumors with regional node metastases present a special set of circumstances. CT or MRI scans are recommended prior to performing random biopsies to search for elusive primary tumors in the upper aerodigestive tract.

Computed tomography treatment planning in IR-192 brachytherapy in the head and neck.

Brachytherapy dose prescription and treatment planning lag behind the state-of-the-art for external beam therapy. As altered fractionation of external beam therapy improves patient outcome in head and neck cancer, there will be an increased need to compare the two radiotherapy techniques. Currently, implant techniques and dose prescription documentation are not uniform, dose prescription to a target volume is subjective, and implant quality is poorly understood and not routinely assessed. All contribute to a lack of scientifically rigorous brachytherapy clinical trials. Studies designed to combine tumor imaging and dosimetry data are important in the evolution of brachytherapy treatment planning. Head and neck implants, which often require nonparallel, arching, or looping source carriers for all but small tumors in order to encompass the target volume adequately, were used to evaluate the clinical utility and feasibility of computed tomography as a treatment planning tool in brachytherapy. Following placement of plastic afterloading tubes under general anesthesia, orthogonal radiographs with dummy sources in the afterloading tubes are obtained as customary for source localization. With the patient in the same position, axial CT scans are obtained with the dummy seeds still in place for treatment planning. The implant physician, using data from the pre-treatment diagnostic CT scan, outlines target areas on sequential images creating a 3-dimensional target volume. By superimposing anatomic data with isodose curves one can objectively define implant parameters important in clinical trials analysis. These include minimum target absorbed dose, implant uniformity, and treatment to target volume ratio. The results of the first 10 patients are presented and implications of these data regarding the analysis of implant technique, implant quality, and implant optimization are discussed. The technique as performed is laborious but practicable in the clinical research setting of head and neck implant. Further research efforts should improve, simplify, and objectify brachytherapy and hasten the time when rigorous multi-institutional brachytherapy trials will be reality.

Failure to detect extramedullary hematopoiesis during bone-marrow imaging with indium-111 or technetium-99m sulfur colloid.

A patient with postpolycythemic myeloid metaplasia developed an enlarging abdominal mass documented on TCT scanning. To distinguish between lymphoma and extramedullary hematopoiesis, marrow elements were imaged with indium-111 chloride and technetium-99m sulfur colloid. Because the mass failed to accumulate either tracer, a presumptive diagnosis of lymphoma was made and exploratory surgery was performed. The excised mass was found to consist of enlarged lymph nodes containing extramedullary hematopoiesis. Caution should be exercised in the use of In-111 or Tc-99m SC bone-marrow scans to diagnose sites of extramedullary hematopoiesis.

Efficacy of gadoteridol for magnetic resonance imaging of extracranial head and neck pathology.

RATIONALE AND OBJECTIVES: This study evaluated the efficacy of gadoteridol in patients with extracranial head and neck pathology. METHODS: One hundred twenty-two magnetic resonance imaging (MRI) cases from a multicenter safety and efficacy trial of gadoteridol in patients with suspected head and neck pathology were randomly assigned for evaluation to one of two blinded neuroradiologists. RESULTS: Enhancement of pathology after gadoteridol injection was noted in 96 cases (78.7%) and provided additional diagnostic information in 57 cases (46.7%). Improved lesion visualization was noted in 37 (64.9%) of these 57 cases; an increase in the number of lesions seen was noted in 4 (7.0%) of 57 cases. Blinded readers determined that additional diagnostic information provided by gadoteridol would have resulted in a change in diagnosis in 20 (35.1%, or 16.4% of total population) of 57 patients. CONCLUSION: These results demonstrate that gadoteridol is an efficacious agent for enhanced MRI of head and neck pathology.

Extracalvarial soft tissues in cranial computed tomography. Normal anatomy and pathology.

Computed tomography has emerged as the modality of choice for imaging soft tissues of the face and neck. However, the extracalvarial soft tissue anatomy has not been delineated. The CT appearance of normal anatomy and variants, including the cutaneous and subcutaneous tissues, muscle layers, and subgaleal space is described. A pathologic spectrum that includes congenital, inflammatory, traumatic, and neoplastic lesions is presented. When appropriate CT windows for viewing the extracalvarial soft tissues are utilized, significant clinical information may be provided.

Sensorineural hearing loss: more than meets the eye?

PURPOSE: To assess the value of MR in patients with sensorineural hearing loss (SNHL) caused by lesions other than acoustic neuromas. METHODS: MR studies of 51 patients with SNHL were retrospectively reviewed; patients with acoustic neuroma were excluded to focus on the more uncommon causes. RESULTS: Twenty patients had labyrinthine lesions. Six patients had viral labyrinthitis, one patient had bacterial labyrinthitis, and one patient had luetic labyrinthitis. Three patients had hemorrhage in the labyrinth, two posttraumatic and one spontaneous from an adjacent temporal bone tumor. Only one of the two patients with traumatic labyrinthine hemorrhage had evidence of a fracture on high-resolution CT. In one patient with CT-proved cochlear otosclerosis, peri-cochlear foci of enhancement were seen on contrast-enhanced MR. Four patients had presumed labyrinthine schwannomas. A middle ear cholesteatoma in one patient invaded the cochlea and resulted in marked cochlear enhancement due to granulation tissue. Thirteen patients had intracanalicular and cerebellopontine angle lesions. The lesions included arteriovenous malformations (three patients), sarcoidosis (three patients), metastasis (two patients), lymphoma (two patients), lipomas (two patients), and postshunt meningeal fibrosis (one patient). Eighteen patients had intra-axial lesions responsible for SNHL. The most common intra-axial lesions were brain stem infarcts and multiple sclerosis. Traumatic lesions in the inferior colliculi, sarcoidosis, lymphoma, and extrinsic compression of the colliculi from a pineal tumor were also noted. CONCLUSION: MR can demonstrate numerous lesions responsible for SNHL other than acoustic neuromas. The entire acoustic pathways, including the labyrinth, internal auditory canal, cerebellopontine angle, and brain stem should be carefully scrutinized for lesions in patients with SNHL. The use of contrast media markedly increases the yield of MR in this clinical situation by demonstrating inflammatory and neoplastic labyrinthine lesions and meningeal pathology (both neoplastic and inflammatory) in the internal auditory canal and cerebellopontine angle cistern.

Optimization of techniques in screening CT of the sinuses.

The number of screening examinations of the sinuses performed with CT has markedly increased owing to the widespread and increasing use of endoscopic sinonasal surgery. We reviewed scans from 500 patients who had screening CT examinations of the sinuses for preendoscopic evaluation of inflammatory sinonasal disease to better define an optimal imaging protocol. Three aspects of direct coronal imaging of the paranasal sinuses were investigated: (1) preparation of the patient prior to the examination; (2) technical factors of the CT study, including positioning of the patient, optimal coronal angle, slice thickness, and CT exposure factors; and (3) data display. Our experience indicates that pretreatment of the patient with maximal medical therapy enables the best preendoscopic definition of anatomy, disease pattern, and nonreversible disease component for the treating surgeon. CT technical factors are optimized with scanning in the prone position with thin (3-mm) sections obtained through the anterior paranasal sinuses. This allows optimal visualization of the ostiomeatal unit. The remaining posterior portions of the sinuses are adequately imaged with thicker slices (5 mm). The coronal scan angle used is less critical. Exposure factors (mAs) can be reduced dramatically without image compromise. Data display is optimized when the bone algorithm is used to acquire the data and with image display at intermediate window center and width level. Use of the techniques outlined in this article results in a cost-effective yet diagnostic scan of the sinuses with decreased radiation exposure to the patient.

Recurring patterns of inflammatory sinonasal disease demonstrated on screening sinus CT.

PURPOSE: In order to define specific features on screening sinus CT (SSCT) that will aid the endoscopic surgeon in his approach to patients with inflammatory sinonasal disease, we sought to answer four questions: 1) what recurring patterns of inflammatory sinonasal disease are evident on SSCT; 2) what is the relative frequency of these recurring patterns; 3) how do these CT patterns correlate with the known sinus mucociliary drainage routes; and 4) what are the characteristic radiologic features of each pattern? METHODS: We reviewed the clinical and radiologic records of 500 consecutive patients who underwent SSCT as a prelude to possible functional endoscopic sinus surgery. RESULTS: Five recurring radiologic patterns of sinonasal inflammatory disease were identified: 1) infundibular (129/500 or 26%), 2) ostiomeatal unit (126/500 or 25%) 3) sphenoethmoidal recess (32/500 or 6%), 4) sinonasal polyposis (49/500 or 10%), and 5) sporadic (unclassifiable) (121/500 or 24%) patterns. Normal SSCT was seen in 133/500 patients (27%). CONCLUSION: Identification of specific patterns of sinonasal disease permits grouping of patients into nonsurgical (normal CT), routine (infundibular, ostiomeatal unit, and most sporadic patterns) and complex (sinonasal polyposis and sphenoethmoidal recess patterns) surgical groups. Assignment of patients to radiologic patterns allows a tailored surgical approach.

'Leave me alone' lesions of the petrous apex.

PURPOSE: When troublesome MR imaging findings are noted in the petrous apex, the radiologist must determine if the area in question needs surgical therapy. Two nonsurgical entities, asymmetric fatty marrow and fluid-filled petrous air cells (trapped fluid), can be noted on conventional brain MR images and confused with pathologic lesions. Our observation that radiologists do not always confidently define the nonsurgical petrous apex lesions precipitated this investigation. METHODS: Twenty-three patients with either asymmetric fatty marrow (six) or unilateral effusion in a pneumatized petrous apex (17) on MR images were studied. Eighteen patients underwent high-resolution temporal bone CT. For all patients, the medical charts were reviewed retrospectively and/or the surgical and clinical follow-up findings were reviewed with the referring physician. RESULTS: In the patients with asymmetric fatty marrow, MR signal intensity followed fat on all sequences. The questioned apex in the patients with trapped fluid showed mixed MR signal characteristics (low to high T1 signal, high T2 signal). CT scans confirmed nonexpansile air-cell opacification. CONCLUSION: Asymmetric fatty marrow in the petrous apex and petrous air-cell effusions have characteristic MR and CT features that facilitate their correct diagnosis. Effusions with intermediate or high T1 signal are most frequently confused with cholesterol granulomas. In those patients, long-term CT follow-up may be helpful to confirm their stability.

Bithalamic hyperintensity on T2-weighted MR: vascular causes and evaluation with MR angiography.

PURPOSE: To determine whether MR angiography can be used to differentiate between the two vascular causes of bithalamic hyperintensity on T2-weighted MR images: "top of the basilar" artery occlusion and deep cerebral vein thrombosis. METHODS: A retrospective review identified six patients with bithalamic T2 hyperintensity of vascular causes. MR angiography was performed in four patients, MR angiography and conventional angiography in one patient, and conventional angiography in one patient. Data pertaining to clinical presentation and hospital course were collected. MR angiographic techniques were multislab overlapping three-dimensional time-of-flight, 2-D time-of-flight, and 2-D phase-contrast. RESULTS: Three cases of top of the basilar artery occlusion and three cases of deep cerebral vein thrombosis were recognized. In all cases, T2 hyperintensity in a vascular distribution suggested cerebral occlusive disease. Infarction involving the thalami and basal ganglia was present in two cases of deep cerebral vein thrombosis. Infarction of the thalami, mesodiencephalic region, and cerebellar hemispheres was present in two cases of basilar artery occlusion. Bithalamic infarction alone was seen in one case of deep cerebral vein thrombosis and one case of basilar artery occlusion. In the five cases in which MR angiography was used, this technique accurately distinguished the vessels involved (arterial or venous). CONCLUSION: MR angiography is a useful adjunct to MR imaging in the evaluation of bithalamic T2 hyperintensity. It does help distinguish between the two vascular causes: top of basilar artery occlusion and deep cerebral vein thrombosis.

MR imaging and MR angiography in the evaluation of pulsatile tinnitus.

PURPOSE: 1) To evaluate the scope of imaging findings seen with spin-echo MR and MR angiography (MRA) in patients with pulsatile tinnitus; 2) to determine whether MRA adds additional imaging information (to that provided by spin-echo MR) necessary for determining the cause of pulsatile tinnitus; and 3) to suggest MR and MRA imaging techniques for evaluation of patients with pulsatile tinnitus. METHODS: Forty-nine patients with pulsatile tinnitus were evaluated with MR and MRA. Seventeen of these patients had conventional angiography. RESULTS: Vascular lesions or paraganglioma were demonstrated in 28 patients. Of these 28 lesions, the majority were seen best (46%) or only (36%) on MRA. The spectrum of lesions detected included dural arteriovenous fistula (nine), extracranial arteriovenous fistula (three), paraganglioma (five), jugular bulb variants (three), aberrant internal carotid artery (one), internal carotid artery stenosis (one), tortuous internal carotid artery (one), carotid dissection with pseudoaneurysm (one), stenosis of the transverse sinus (two), and arteriovenous malformation (two). CONCLUSIONS: MRA, in conjunction with spin-echo imaging, markedly enhances the ability of MR to diagnose the lesions responsible for pulsatile tinnitus.

CT/MR spectrum of far lateral and anterior lumbosacral disk herniations.

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.

Radiographic evaluation of brachial plexopathy.

Neurologic signs and symptoms of brachial plexopathy may be subtle or confusing, making clinical localization of disease along the length of the brachial plexus difficult. To determine the most direct radiographic approach to diagnosing and anatomically delineating the cause of brachial plexopathy, we reviewed the clinical and radiographic records of 43 patients presenting with signs and symptoms referable to the brachial plexus who received CT and/or myelography as part of their radiographic evaluation. The study population was divided into two groups, those with and those without trauma. Significant deficiencies were detected in the radiographic evaluation of the nontraumatic group, with 35% of these patients having an incomplete or inappropriate CT examination that failed to visualize the full extent of the brachial plexus. In four patients, this led to a significant (greater than 6 months) delay in diagnosis. It was concluded that trauma patients presenting with brachial plexus symptoms should have cervical myelography first, rather than CT. Patients without a history of trauma should be classified on the basis of clinical findings as having central (cord, epidural space, neural foramen) or peripheral (retroclavicular space, axillary apex) disease. If the abnormality is central, myelography should be the first technique used; if peripheral disease is present, CT should be the first study. If the disease extends beyond the confines of the anatomic compartment suggested clinically, the other technique should be used for further evaluation. CT scan protocols for brachial plexus evaluation should employ bolus/drip contrast enhancement to distinguish vascular structures from masses.(ABSTRACT TRUNCATED AT 250 WORDS)