Imaging of Surgical Free Flaps in Head and Neck Reconstruction.

Head and neck surgical reconstruction is complex, and postoperative imaging interpretation is challenging. Surgeons now use microvascular free tissue transfer, also known as free flaps, more frequently in head and neck reconstruction than ever before. Thus, an understanding of free flaps, their expected appearance on cross-sectional imaging, and their associated complications (including tumor recurrence) is crucial for the interpreting radiologist. Despite the complexity and increasing frequency of free flap reconstruction, there is no comprehensive head and neck resource intended for the radiologist. We hope that this image-rich review will fill that void and serve as a go to reference for radiologists interpreting imaging of surgical free flaps in head and neck reconstruction.

Initial Performance of NI-RADS to Predict Residual or Recurrent Head and Neck Squamous Cell Carcinoma.

BACKGROUND AND PURPOSE: The Head and Neck Imaging Reporting and Data System (NI-RADS) surveillance template for head and neck cancer includes a numeric assessment of suspicion for recurrence (1-4) for the primary site and neck. Category 1 indicates no evidence of recurrence; category 2, low suspicion of recurrence; category 3, high suspicion of recurrence; and category 4, known recurrence. Our purpose was to evaluate the performance of the NI-RADS scoring system to predict local and regional disease recurrence or persistence. MATERIALS AND METHODS: This study was classified as a quality-improvement project by the institutional review board. A retrospective database search yielded 500 consecutive cases interpreted using the NI-RADS template. Cases without a numeric score, non-squamous cell carcinoma primary tumors, and primary squamous cell carcinoma outside the head and neck were excluded. The electronic medical record was reviewed to determine the subsequent management, pathology results, and outcome of clinical and radiologic follow-up. RESULTS: A total of 318 scans and 618 targets (314 primary targets and 304 nodal targets) met the inclusion criteria. Among the 618 targets, 85.4% were scored NI-RADS 1; 9.4% were scored NI-RADS 2; and 5.2% were scored NI-RADS 3. The rates of positive disease were 3.79%, 17.2%, and 59.4% for each NI-RADS category, respectively. Univariate association analysis demonstrated a strong association between the NI-RADS score and ultimate disease recurrence, with P < .001 for primary and regional sites. CONCLUSIONS: The baseline performance of NI-RADS was good, demonstrating significant discrimination among the categories 1-3 for predicting disease.

Difficult Lumbar Puncture: Pitfalls and Tips from the Trenches.

Lumbar puncture has, for many years, been the responsibility of the internal medicine physician or the neurologist. As more patients have undergone spine surgery and with the current increase in body mass index of the general population, the radiologist has been consulted with increasing frequency to perform lumbar puncture with fluoroscopic guidance. Radiology, in fact, is now the dominant overall provider of lumbar puncture procedures. The procedure is more difficult when the needle length increases, and if fluoroscopy is used, landmarks are more difficult to visualize with increasing subcutaneous fat. Our goal with this review was to describe our techniques for lumbar puncture in the difficult patient, with emphasis on using fluoroscopy in the obese patient and to suggest maneuvers that might make the procedure easier. Combining our experience from performing these procedures on an obese population, we would like to share our tips, especially with trainees early in their career.

CT Accuracy of Extrinsic Tongue Muscle Invasion in Oral Cavity Cancer.

BACKGROUND AND PURPOSE: Extrinsic tongue muscle invasion in oral cavity cancer upstages the primary tumor to a T4a. Despite this American Joint Committee on Cancer staging criterion, no studies have investigated the accuracy or prognostic importance of radiologic extrinsic tongue muscle invasion, the feasibility of standardizing extrinsic tongue muscle invasion reporting, or the degree of agreement across different disciplines: radiology, surgery, and pathology. The purpose of this study was to assess the agreement among radiology, surgery, and pathology for extrinsic tongue muscle invasion and to determine the imaging features most predictive of extrinsic tongue muscle invasion with surgical/pathologic confirmation. MATERIALS AND METHODS: Thirty-three patients with untreated primary oral cavity cancer were included. Two head and neck radiologists, 3 otolaryngologists, and 1 pathologist prospectively evaluated extrinsic tongue muscle invasion. RESULTS: Fourteen of 33 patients had radiologic extrinsic tongue muscle invasion; however, only 8 extrinsic tongue muscle invasions were confirmed intraoperatively. Pathologists were unable to determine extrinsic tongue muscle invasion in post-formalin-fixed samples. Radiologic extrinsic tongue muscle invasion had 100% sensitivity, 76% specificity, 57% positive predictive value, and 100% negative predictive value with concurrent surgical-pathologic evaluation of extrinsic tongue muscle invasion as the criterion standard. On further evaluation, the imaging characteristic most consistent with surgical-pathologic evaluation positive for extrinsic tongue muscle invasion was masslike enhancement. CONCLUSIONS: Evaluation of extrinsic tongue muscle invasion is a subjective finding for all 3 disciplines. For radiology, masslike enhancement of extrinsic tongue muscle invasion most consistently corresponded to concurrent surgery/pathology evaluation positive for extrinsic tongue muscle invasion. Intraoperative surgical and pathologic evaluation should be encouraged to verify radiologic extrinsic tongue muscle invasion to minimize unnecessary upstaging. Because this process is not routine, imaging can add value by identifying those cases most suspicious for extrinsic tongue muscle invasion, thereby prompting this more detailed evaluation by surgeons and pathologists.

Do Radiologists Report the TNM Staging in Radiology Reports for Head and Neck Cancers? A National Survey Study.

BACKGROUND AND PURPOSE: CT and MR imaging are widely used for the staging of head and neck cancer. Currently, there are no data regarding whether the primary tumor, nodes, metastasis (TNM) staging is routinely incorporated into radiology reports. We conducted a national survey to determine whether radiologists routinely address staging, in particular regarding T (primary tumor) and N (nodal). MATERIALS AND METHODS: The survey was sent to 782 members of the American Society of Head and Neck Radiology. The survey asked whether they assign TN staging in reports. If they do assign TN staging, what are the reasons for doing so, and if not, what are the barriers or reasons for not including it in the radiology report? The method of measuring the size of the primary tumor and pathologic lymph nodes was also queried. RESULTS: A total of 229 responses were returned (29.3% response rate). Approximately half (49%; 95% confidence interval, 43.55-54.5%) of the responders thought that incorporating TN staging is important. However, only 24.5% (95% confidence interval, 19.8%-29.2%) stated that they routinely assigned TN staging in their radiology reports. The most common barriers were being afraid of being inaccurate (59%) and being unable to remember the staging classifications (58.2%); 76.9% indicated that they measure a primary tumor in 3D. CONCLUSIONS: Staging head and neck cancer based on imaging presents unique challenges. Nearly half of the responding radiologists think it is important to incorporate TN staging in radiology reports, though only a quarter of them routinely do so in practice.

Accuracy of Preoperative Imaging in Detecting Nodal Extracapsular Spread in Oral Cavity Squamous Cell Carcinoma.

BACKGROUND AND PURPOSE: The increasing impact of diagnosing extracapsular spread by using imaging, especially in patients with oropharyngeal squamous cell carcinoma, highlights the need to rigorously evaluate the diagnostic accuracy of imaging. Previous analysis suggested 62.5%-80.9% sensitivity and 60%-72.7% specificity. Our goals were to evaluate the accuracy of imaging in diagnosing extracapsular spread in a cohort of patients with oral cavity squamous cell carcinoma (pathologic confirmation of extracapsular spread routinely available), as a proxy for oropharyngeal squamous cell carcinoma, and to independently assess the reliability of imaging features (radiographic lymph node necrosis, irregular borders/stranding, gross invasion, and/or node size) in predicting pathologically proven extracapsular spread. MATERIALS AND METHODS: One hundred eleven consecutive patients with untreated oral cavity squamous cell carcinoma and available preoperative imaging and subsequent lymph node dissection were studied. Two neuroradiologists blinded to pathologically proven extracapsular spread status and previous radiology reports independently reviewed all images to evaluate the largest suspicious lymph node along the expected drainage pathway. Radiologic results were correlated with pathologic results from the neck dissections. RESULTS: Of 111 patients, 29 had radiographically determined extracapsular spread. Pathologic examination revealed that 28 of 111 (25%) had pathologically proven extracapsular spread. Imaging sensitivity and specificity for extracapsular spread were 68% and 88%, respectively. Radiographs were positive for lymph node necrosis in 84% of the patients in the pathology-proven extracapsular spread group and negative in only 7% of those in the pathologically proven extracapsular spread-negative group. On logistic regression analysis, necrosis (P = .001), irregular borders (P = .055), and gross invasion (P = .068) were independently correlated with pathologically proven extracapsular spread. CONCLUSIONS: Although the specificity of cross-sectional imaging for extracapsular spread was high, the sensitivity was low. Combined logistic regression analysis found that the presence of necrosis was the best radiologic predictor of pathologically proven extracapsular spread, and irregular borders and gross invasion were nearly independently significant.

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.

Fluoroscopic-guided lumbar puncture: fluoroscopic time and implications of body mass index--a baseline study.

BACKGROUND AND PURPOSE: Fluoroscopic-guided lumbar puncture is an effective alternative to bedside lumbar puncture in challenging patients. However, no published guidelines are available for an acceptable range of fluoroscopic time for this procedure. The purpose of this study was to set department benchmark fluoroscopic times for lumbar puncture, accounting for body mass index in our patient population. MATERIALS AND METHODS: We identified and reviewed all patients who underwent fluoroscopic-guided lumbar puncture at 4 hospitals during a 2-year period (July 2011 to June 2013). Data collection included patient information (demographics, body mass index, history of prior lumbar surgery and/or lumbar hardware, scoliosis); procedure details (fluoroscopic time, level of access, approach, needle gauge and length); level of operator experience; and hospital site. A generalized linear model was used to test whether body mass index influenced fluoroscopic time while controlling other factors. RESULTS: Five hundred eighty-four patients (mean age, 47.8 ± 16.2 years; range, 16-92 years; 33% male) had successful fluoroscopic-guided lumbar puncture s. Mean body mass index and fluoroscopic time were higher in female patients (34.4 ± 9.9 kg/m(2) and 1.07 minutes; 95% CI, 0.95-1.20) than in male patients (29.2 ± 7.3 kg/m(2) and 0.91 minutes; 95% CI, 0.79-1.03). Body mass index (P = .001), hospital site (P < .001), and level of experience (P = .03) were factors significantly affecting fluoroscopic time on multivariate analysis. Benchmark fluoroscopic times in minutes were the following: 0.48 (95% CI, 0.40-0.56) for normal, 0.61 for overweight (95% CI, 0.52-0.71), 0.63(95% CI, 0.58-0.73) for obese, and 0.86 (95% CI, 0.74-1.01) in extremely obese body mass index categories. CONCLUSIONS: In patients undergoing fluoroscopic-guided lumbar punctures, fluoroscopy time increased with body mass index We established benchmark fluoroscopic-guided lumbar puncture time ranges as related to body mass index in our patient population.

Incidence of cerebellar tonsillar ectopia in idiopathic intracranial hypertension: a mimic of the Chiari I malformation.

BACKGROUND AND PURPOSE: IIH is a syndrome of elevated intracranial pressure without hydrocephalus, mass, or identifiable cause. Diagnosis is made by clinical presentation, intracranial pressure measurement, and supportive imaging findings. A subset of patients with IIH may have tonsillar ectopia, meeting the criteria for Chiari malformation type I but not responding to surgical decompression for Chiari I. The purpose of this study was to determine the incidence and morphology of cerebellar tonsillar ectopia in patients with IIH. MATERIALS AND METHODS: Forty-three patients with clinically confirmed IIH and 44 age-matched controls were included. Two neuroradiologists with CAQs reviewed sagittal T1-weighted MRI in a blinded fashion and measured cerebellar tonsil and obex positions relative to the foramen magnum and prepontine cistern width at the level of the midpons. RESULTS: Nine of 43 patients with IIH and 1/44 controls had cerebellar tonsillar ectopia of ≥5 mm. Five of 9 of patients with IIH with ectopia of ≥5 mm also had a "peglike" tonsil configuration. Patients with IIH had a significantly lower tonsillar position (2.1 ± 2.8 mm) than age-matched controls (0.7 ±1.9 mm, P < .05). The obex position was significantly lower in patients with IIH versus controls (-7.9 mm [above the FM] versus -9.4 mm [above the FM], P < .05). The prepontine width was not significantly different between the groups. CONCLUSIONS: Cerebellar tonsil position in patients with IIH was significantly lower than that in age-matched controls, often times peglike, mimicking Chiari I. A significantly lower obex position suggests an inferiorly displaced brain stem and cerebellum. When tonsillar ectopia of >5 mm is identified, imaging and clinical consideration of IIH are warranted to avoid misdiagnosis as Chiari I.

CSF leaks: correlation of high-resolution CT and multiplanar reformations with intraoperative endoscopic findings.

BACKGROUND AND PURPOSE: Skull base defects can result in CSF leaks, with meningitis as a potential complication. Surgeons are now routinely repairing these leaks via a nasal endoscopic approach. Accurate preoperative imaging is essential for surgical planning. A variety of imaging regimens have been employed, including axial and direct coronal CT, CT cisternography with iodinated contrast, radionuclide cisternography, and MR imaging. Now that multidetector helical CT is available, the purpose of this study was to determine how well coronal and sagittal multiplanar reformatted (MPR) images generated from a high-resolution axial dataset correlate with intraoperative findings in a group of patients with clinically proved CSF leaks. MATERIALS AND METHODS: We retrospectively reviewed imaging findings and surgical records of 19 patients who presented to our tertiary care institution during a 2.5-year period with clinically proved CSF leak. Patients underwent preoperative imaging with high-resolution helical CT (section collimation, 10 patients with 0.625-mm and 9 patients with 1.25-mm images), with MPR images processed by a neuroradiologist at a workstation. Two neuroradiologists, blinded to the intraoperative findings, determined the location and size of the skull base defects. All patients underwent endoscopic evaluation by an experienced sinonasal otolaryngologist, who confirmed the site of the CSF leak by direct inspection and measured the corresponding osseous defect. CT was considered accurate if it correctly localized the CSF leak and was within 2 mm of the endoscopic measurement. RESULTS: At endoscopy, 22 leaks of CSF were identified in 18 of 19 patients. CT correctly predicted the site of the leak in 20 (91%) of 22 cases and was accurate (within 2 mm of the endoscopic measurement) in 15 (75%) of 20 cases preoperatively localized. The CT measurement of the skull base defect differed from the endoscopic size in 5 (25%) of 20 cases, ranging from 7.4 mm below to 13 mm above the intraoperative measurement. When analysis was limited to the subgroup of 10 patients who had 0.625-mm axial images, the accuracy was improved, and of the 11 CSF leaks described at CT, all were verified at endoscopy. In addition, the submillimeter CT accurately measured the size of the osseous defect in 9 (82%) of 11 cases. In the remaining 2 (18%) of 11 cases, CT minimally overestimated the size of the osseous defect by only 3 mm. CONCLUSION: Axial images, and coronal, sagittal, and oblique MPR images generated from high-resolution axial CT performed well preoperatively, localizing the skull base defect responsible for the CSF leak. However, active manipulation of the axial dataset at a workstation is crucial in identifying and correctly describing these lesions. When submillimeter collimation is available, measurement of the osseous defects are accurate most of the time.

Optimization of Z-axis automatic exposure control for multidetector row CT evaluation of neck and comparison with fixed tube current technique for image quality and radiation dose.

BACKGROUND AND PURPOSE: Z-axis automatic exposure control (AEC) technique automatically adjusts tube current based on size of body region scanned. The purpose of the current study was to compare diagnostic acceptability, noise, and radiation exposure of multidetector row CT (MDCT) of neck performed with z-axis AEC and with fixed current. MATERIALS AND METHODS: Two study groups of 26 patients each underwent MDCT of neck using z-axis AEC with 8 noise index (NI), 150-440 mA, and 10 NI, 75-440 mA, respectively. A control group consisting of another 26 patients underwent MDCT of neck with fixed-current technique (300 mA). Objective noise and mean tube current-time products (mA . s) were recorded. Two radiologists evaluated images for diagnostic acceptability and subjective noise on a 5-point scale. RESULTS: All CT examinations of study and control groups were diagnostically acceptable, though objective noise was significantly more with z-axis AEC (shoulder: NI 8, 20.6 +/- 6.2 HU; NI 10, 22.2 +/- 4.6 HU) than with fixed current (16.2 +/- 6 HU) (P = .01). There was no significant difference between AEC and fixed current in diagnostic acceptability and subjective noise (P = .22-.42). AEC resulted in significant radiation dose reduction (NI 8, 186.3 +/- 20.5 mA . s; NI 10, 158.1 +/- 21.2 mA x s), compared with fixed current (235 +/- 21.8 mA x s). CONCLUSION: Z-axis AEC resulted in similar subjective noise and diagnostic acceptability, with radiation dose reduction of 21% for NI of 8 and 33% for NI of 10, respectively, for MDCT evaluation of neck, compared with those of fixed current technique.

CT arteriography and venography in pulsatile tinnitus: preliminary results.

BACKGROUND AND PURPOSE: Pulsatile tinnitus (PT), a common disorder, can be caused by a variety of otologic and vascular lesions. Various imaging modalities, including CT, MR imaging and angiography, and conventional angiography, have been used in the assessment of PT. Ideally, a single imaging study to evaluate for the largest variety of etiologies would be optimal. In our study, we examine the potential for CT arteriography and venography (CTA/V) in the evaluation of PT. METHODS: Sixteen patients with PT were prospectively evaluated by an otolaryngologist, had a normal otologic examination, and were referred for a CTA/V. All examinations were performed on a 16-section multidetector CT. The carotid bifurcations, internal carotid artery course, transverse and sigmoid sinuses, jugular foramen, internal jugular vein, sella turcica, and temporal bones were evaluated. RESULTS: Seven of the 16 patients had lesions on CTA/V that could account for their PT. Examples of pathologic conditions in the series included a significantly dominant venous system, a venous diverticulum with stricture, and a transverse sinus stenosis. CONCLUSIONS: Preliminary findings indicate that CTA/V can be a valuable imaging tool in the assessment of PT. With this technique, arterial, venous, middle, and inner ear causes of PT can be excluded.

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.

Diffusion weighted imaging in radiation necrosis.

This case report suggests that magnetic resonance imaging with diffusion weighted imaging may help distinguish between tumour recurrence and radiation induced necrosis in patients previously treated for a brain tumour.

Diffusion-weighted MR imaging of the normal human spinal cord in vivo.

BACKGROUND AND PURPOSE: Diffusion-weighted imaging is a robust technique for evaluation of a variety of neurologic diseases affecting the brain, and might also have applications in the spinal cord. The purpose of this study was to determine the feasibility of obtaining in vivo diffusion-weighted images of the human spinal cord, to calculate normal apparent diffusion coefficient (ADC) values, and to assess cord anisotropy. METHODS: Fifteen healthy volunteers were imaged using a multi-shot, navigator-corrected, spin-echo, echo-planar pulse sequence. Axial images of the cervical spinal cord were obtained with diffusion gradients applied along three orthogonal axes (6 b values each), and ADC values were calculated for white and gray matter. RESULTS: With the diffusion gradients perpendicular to the orientation of the white matter tracts, spinal cord white matter was hyperintense to central gray matter at all b values. This was also the case at low b values with the diffusion gradients parallel to the white matter tracts; however, at higher b values, the relative signal intensity of gray and white matter reversed. With the diffusion gradients perpendicular to spinal cord, mean ADC values ranged from 0.40 to 0.57 x 10(-3) mm2/s for white and gray matter. With the diffusion gradients parallel to the white matter tracts, calculated ADC values were significantly higher. There was a statistically significant difference between the ADCs of white versus gray matter with all three gradient directions. Strong diffusional anisotropy was observed in spinal cord white matter. CONCLUSION: Small field-of-view diffusion-weighted images of the human spinal cord can be acquired in vivo with reasonable scan times. Diffusion within spinal cord white matter is highly anisotropic.

A high-resolution fast spin-echo inversion-recovery sequence for preoperative localization of the internal globus pallidus.

A fast spin-echo inversion-recovery (FSE-IR) sequence is described for its utility regarding surgical planning for patients with Parkinson's disease (PD) who are undergoing microelectrode-guided internal globus pallidus (GPi) ablation. Images from thirty-seven adult patients with PD were reviewed and visualization of the GPi, globus pallidus externa (GPe), and the intervening lamina was noted. High-resolution images were acquired from all patients despite the external hardware and the patients' movement disorder. In all cases, the conventional surgical trajectory, determined indirectly by a fixed measurement from the anteroposterior commissure line, was modified by the ability to visualize the GPi and optic tract directly. This sequence facilitated accurate stereotactic targeting.

MR characteristics of muslin-induced optic neuropathy: report of two cases and review of the literature.

Muslin-induced optic neuropathy is a rarely reported but important cause of delayed visual loss after repair of intracranial aneurysms. Most of the previously reported cases were published before the introduction of MR imaging. We describe the clinical features and MR appearance of two cases of delayed visual loss due to "muslinoma," and compare them with the 21 cases reported in the literature.