Imaging of endoscopic approaches to the anterior and central skull base.

Sinonasal endoscopy for treatment of benign sinonasal diseases is a well-established procedure. Recent advances in endoscope technology have substantially expanded its application with many institutions now offering resection of skull base lesions and sinonasal malignancies via the endoscopic approach. Its minimally invasive nature leads to faster recovery time, better cosmetic results, and fewer complications. Unfortunately, not all lesions involving the sinonasal region and skull base are accessible to sinonasal endoscopy. In addition, many of these disease processes are not directly visible on clinical examination. Therefore, the surgeon relies upon imaging to (1) determine the extent and possible nature of the disease; (2) provide guidance for surgical planning purposes, in particular, if a lesion is accessible to endoscopic surgery or if an open surgical approach is indicated. The radiologist, on the other hand, needs to be familiar with the technical limitations and contraindications of sinonasal endoscopy to provide a meaningful radiology report to the surgeon. The relative and absolute contraindications to endoscopic surgery can be categorised into technical factors, extent of a lesion, tumour vascularity, and anatomical variations and are discussed in this review article.

Reduction of Motion Artifacts and Noise Using Independent Component Analysis in Task-Based Functional MRI for Preoperative Planning in Patients with Brain Tumor.

BACKGROUND AND PURPOSE: Although it is a potentially powerful presurgical tool, fMRI can be fraught with artifacts, leading to interpretive errors, many of which are not fully accounted for in routinely applied correction methods. The purpose of this investigation was to evaluate the effects of data denoising by independent component analysis in patients undergoing preoperative evaluation for glioma resection compared with more routinely applied correction methods such as realignment or motion scrubbing. MATERIALS AND METHODS: Thirty-five functional runs (both motor and language) in 12 consecutive patients with glioma were analyzed retrospectively by double-blind review. Data were processed and compared with the following: 1) realignment alone, 2) motion scrubbing, 3) independent component analysis denoising, and 4) both independent component analysis denoising and motion scrubbing. Primary outcome measures included a change in false-positives, false-negatives, z score, and diagnostic rating. RESULTS: Independent component analysis denoising reduced false-positives in 63% of studies versus realignment alone. There was also an increase in the z score in areas of true activation in 71.4% of studies. Areas of new expected activation (previous false-negatives) were revealed in 34.4% of cases with independent component analysis denoising versus motion scrubbing or realignment alone. Of studies deemed nondiagnostic with realignment or motion scrubbing alone, 65% were considered diagnostic after independent component analysis denoising. CONCLUSIONS: The addition of independent component analysis denoising of fMRI data in preoperative patients with glioma has a significant impact on data quality, resulting in reduced false-positives and an increase in true-positives compared with more commonly applied motion scrubbing or simple realignment methods.

Acute Invasive Fungal Rhinosinusitis: A Comprehensive Update of CT Findings and Design of an Effective Diagnostic Imaging Model.

BACKGROUND AND PURPOSE: Acute invasive fungal rhinosinusitis carries a high mortality rate. An easy-to-use and accurate predictive imaging model is currently lacking. We assessed the performance of various CT findings for the identification of acute invasive fungal rhinosinusitis and synthesized a simple and robust diagnostic model to serve as an easily applicable screening tool for at-risk patients. MATERIALS AND METHODS: Two blinded neuroradiologists retrospectively graded 23 prespecified imaging abnormalities in the craniofacial region on craniofacial CT examinations from 42 patients with pathology-proven acute invasive fungal rhinosinusitis and 42 control patients proved negative for acute invasive fungal rhinosinusitis from the same high-risk population. A third blinded neuroradiologist decided discrepancies. Specificity, sensitivity, positive predictive value, and negative predictive value were determined for all individual variables. The 23 variables were evaluated for intercorrelations and univariate correlations and were interrogated by using stepwise linear regression. RESULTS: Given the low predictive value of any individual variable, a 7-variable model (periantral fat, bone dehiscence, orbital invasion, septal ulceration, pterygopalatine fossa, nasolacrimal duct, and lacrimal sac) was synthesized on the basis of multivariate analysis. The presence of abnormality involving a single variable in the model has an 87% positive predictive value, 95% negative predictive value, 95% sensitivity, and 86% specificity (R(2) = 0.661). A positive outcome in any 2 of the model variables predicted acute invasive fungal rhinosinusitis with 100% specificity and 100% positive predictive value. CONCLUSIONS: Our 7-variable CT-based model provides an easily applicable and robust screening tool to triage patients at risk for acute invasive fungal rhinosinusitis into a disease-positive or -negative category with a high degree of confidence.

Contrast-enhanced MR imaging of brain lesions: a large-scale intraindividual crossover comparison of gadobenate dimeglumine versus gadodiamide.

BACKGROUND AND PURPOSE: The higher relaxivity of gadobenate dimeglumine compared with gadodiamide is potentially advantageous for contrast-enhanced brain MR imaging. This study intraindividually compared 0.1-mmol/kg doses of these agents for qualitative and quantitative lesion enhancement. MATERIALS AND METHODS: Adult patients with suggested or known brain lesions underwent 2 identical MR imaging examinations at 1.5T, one with gadobenate dimeglumine and the other with gadodiamide. The agents were administered in randomized order separated by 3-14 days. Imaging sequences and postinjection acquisition timing were identical for the 2 examinations. Three blinded readers evaluated images qualitatively for diagnostic information (lesion extent, delineation, morphology, enhancement, and global preference) and quantitatively for contrast-to-noise ratio (CNR). RESULTS: One hundred thirteen of 138 enrolled patients successfully underwent both examinations. Final diagnoses were intra-axial tumor, metastasis, extra-axial tumor, or other (47, 27, 18, and 21 subjects, respectively). Readers 1, 2, and 3 demonstrated global preference for gadobenate dimeglumine in 63 (55.8%), 77 (68.1%), and 73 (64.6%) patients, respectively, compared with 3, 2, and 3 patients for gadodiamide (P < .0001, all readers). Highly significant (P < .0001, all readers) preference for gadobenate dimeglumine was demonstrated for all qualitative end points and for CNR (increases of 23.3%-34.7% and 42.4%-48.9% [spin-echo and gradient-refocused echo sequences, respectively] for gadobenate dimeglumine compared with gadodiamide). Inter-reader agreement was good for all evaluations (kappa = 0.47-0.69). Significant preference for gadobenate dimeglumine was demonstrated for all lesion subgroup analyses. CONCLUSION: Significantly greater diagnostic information and lesion enhancement are achieved on brain MR imaging with 0.1-mmol/kg gadobenate dimeglumine compared with gadodiamide at an equivalent dose.

Aceruloplasminaemia with progressive atrophy without brain iron overload: treatment with oral chelation.

BACKGROUND: Hereditary aceruloplasminaemia is a disorder of iron metabolism that is characterised by iron accumulation in the brain and other visceral organs. In previously reported cases, individuals with the disorder were noted to have evidence of iron accumulation in the brain. Oral chelating agents have not been used in neurological diseases of iron metabolism. METHODS: A 54-year-old woman who presented with ataxia, lower extremity spasticity and chorea was evaluated for evidence of the source of neurological dysfunction. RESULTS: Blood studies revealed no detectable ceruloplasmin. Marked iron overload was defined by a liver biopsy, which showed a variegated pattern consistent with a primary cause of iron overload. Review of MRI scans showed progressive brain atrophy without visible iron accumulation occurring over a 5-year period. The history suggested that neurodegeneration was coincident with aggressive oral iron replacement. Oral chelation improved many symptoms. CONCLUSIONS: Our findings in this patient suggest that disorders of iron transport such as aceruloplasminaemia can be a cause of neurological symptoms such as chorea and cognitive decline, as well as progressive neurodegeneration in the absence of visible iron on MRI scans. We found that oral iron chelation was effective at improving symptoms.

Orbital complications of functional endoscopic sinus surgery: MR and CT findings.

AIM: To describe the radiological findings of ophthalmic complications during functional endoscopic sinus surgery (FESS) and correlate them with the clinical manifestations and mechanisms of injury. METHODS: This was a retrospective review of the clinical and cross-sectional imaging findings of 9 patients with orbital complications during FESS. RESULTS: The most common site of entry into the orbit during FESS was the lower medial orbital wall (7 of 9), followed by the inferior orbital wall, resulting in injury to the medial rectus (4 of 9) and, less frequently, the inferior rectus (2 of 9) or superior oblique muscles (1 of 9). Extensive scarring on imaging (3 of 9) was associated with global ocular motility dysfunction. In contrast, localized scarring (3 of 9) or extraocular muscle trauma (6 of 9) resulted in disturbance of eye movement in the direction of gaze from the injured site. CONCLUSIONS: Orbital magnetic resonance and computed tomography findings correlate very well with the abnormal eye movements clinically observed, and can assist in clarifying the cause of injury and guide surgical corrective management of patients suffering orbital complications from FESS. Radiologists should be familiar with the recent developments in FESS instrumentation as well as with the most commonly injured structures within the orbit.

Postcricoid region and cervical esophagus: normal appearance at CT and MR imaging.

PURPOSE: To establish the normal variations of the postcricoid portion of the hypopharynx, esophageal verge, and cervical esophagus, as seen on computed tomographic (CT) and magnetic resonance (MR) images. MATERIALS AND METHODS: One hundred twenty-one CT and 92 MR images were reviewed. Diameter and wall thickness were measured at multiple levels. Depiction of the layers of the musculature and adjacent fat planes was evaluated. The frequency and size of the tracheoesophageal lymph nodes were noted. RESULTS: An esophageal anteroposterior diameter greater than 16 mm and lateral diameter greater than 24 mm were considered abnormal. The average wall thickness was 4.8 mm laterally and 3.8 mm posteriorly. Demonstration of the intramural fat planes of the postcricoid region decreased from the upper to the lower region of the cricoid cartilage. The ability to separate the esophageal wall from the trachea was highest at the esophageal verge and declined markedly more distally. The tracheo-esophageal groove nodes were seen more often on the right (mean size [+/- SD], 4.5 mm +/- 2.2). CONCLUSION: Knowledge of the normal appearance and variations of the post-cricoid region and cervical esophagus is essential in detecting abnormalities in these areas.

CT features of congenital nasal piriform aperture stenosis: initial experience.

PURPOSE: To describe the computed tomographic (CT) measurements and features that enable accurate diagnosis of congenital nasal piriform aperture stenosis (CNPAS). MATERIALS AND METHODS: The clinical and imaging features of six patients (age range, 0-11 months) with CNPAS were retrospectively evaluated and compared with those of 61 control subjects younger than 24 months. RESULTS: The average widths of the piriform aperture in patients aged 0-3, 4-6, and 10-12 months were 4.8, 7.0, and 6.0 mm, respectively, compared with 13.4 (P < .001), 14.9, and 15.6 mm, respectively, in the age-matched control subjects. The average areas of the piriform aperture in patients in the three age groups measured 0.24, 0.46, and 0.36 cm2, respectively, compared with 0.67 (P < .001), 0.86, and 1.11 cm2, respectively, in the age-matched control subjects. The width of the nasal cavity in patients with CNPAS was in the less than 5th percentile compard with that in the control subjects. Abnormal dentition and a midline bone ridge projecting from the inferior palate were present in all six patients. CONCLUSION: CT measurement of the piriform aperture width is a simple and accurate method for diagnosing CNPAS; a width less than 11 mm in a term infant is considered to be diagnostic. An abnormal dentition and a bone ridge along the underside of the palate are confirmatory imaging findings.

Arytenoid cartilage sclerosis: normal variations and clinical significance.

PURPOSE: Our purpose was to determine the variation in location, distribution, and sex predilection of arytenoid cartilage sclerosis in a population of patients without laryngeal cancer as an aid to understanding the significance of this entity when seen in patients with laryngeal cancer. METHODS: One hundred CT examinations of patients of different ages and with no history of laryngeal cancer or radiation therapy were evaluated for the presence of arytenoid cartilage sclerosis. The arytenoid cartilage was subdivided into three regions: superior process, body, and vocal process. Each region was assessed on each side separately on bone window scans. RESULTS: Arytenoid cartilage sclerosis was seen in 16% (n = 16) of the patients. Sclerosis was most common in the body (n = 12) and least common in the true vocal process (n = 2); the left side was the preferred location for all three regions. In 50% of the patients, at least two regions were affected. Eighty-one percent of sclerotic arytenoid cartilage was seen in women. CONCLUSION: Knowledge of the frequency and distribution of arytenoid cartilage sclerosis as a normal variant can aid in determining the risk of arytenoid cartilage involvement in patients with laryngeal cancer.