Faculty Bibliography

OBJECTIVE. Traditional fat-suppressed T1-weighted spin-echo or turbo spin-echo (TSE) sequences (T1-weighted images) may be degraded by motion and pulsation artifacts in head-and-neck studies. Our purpose is to evaluate the role of a fat-suppressed T1-weighted 3D radial gradient-recalled echo sequence (radial-volumetric interpolated breath-hold examination [VIBE]) in the head and neck as compared with standard contrast-enhanced fat-suppressed T1-weighted images. MATERIALS AND METHODS. We retrospectively evaluated 21 patients (age range, 9-67 years) who underwent head-and-neck MRI at 1.5 T. Both contrast-enhanced radial-VIBE and conventional fat-suppressed TSE contrast-enhanced T1-weighted imaging were performed. Two radiologists evaluated multiple parameters of image quality, graded on a 5-point scale. Mixed-model analysis of variance and interobserver variability assessment were performed. RESULTS. The following parameters were scored as significantly better for the contrast-enhanced radial-VIBE sequence than for conventional contrast-enhanced T1-weighted imaging: overall image quality (p < 0.0001), degree of fat suppression (p = 0.006), mucosal enhancement (p = 0.004), muscle edge clarity (p = 0.049), vessel clarity (p < 0.0001), respiratory motion artifact (p = 0.002), pulsation artifact (p < 0.0001), and lesion edge sharpness (p = 0.004). Interobserver agreement in qualitative evaluation of the two sequences showed fair-to-good agreement for the following variables: overall image quality (intraclass correlation coefficient [ICC], 0.779), degree of fat suppression (ICC, 0.716), mucosal enhancement (ICC, 0.693), muscle edge clarity (ICC, 0.675), respiratory motion artifact (ICC, 0.516), lesion enhancement (ICC, 0.410), and lesion edge sharpness (ICC, 0.538). Excellent agreement was shown for vessel clarity (ICC, 0.846) and pulsation artifact (ICC, 0.808). CONCLUSION. The radial-VIBE sequence is a viable motion-robust improvement on the conventional fat-suppressed T1-weighted sequence.

BACKGROUND AND PURPOSE: The differentiation of pilocytic astrocytomas and high-grade astrocytomas is sometimes difficult. There are limited comparisons in the literature of the advanced MR imaging findings of pilocytic astrocytomas versus high-grade astrocytomas. The purpose of this study was to assess the MR imaging, PWI, DWI, and MR spectroscopy characteristics of pilocytic astrocytomas compared with high-grade astrocytomas. MATERIALS AND METHODS: Sixteen patients with pilocytic astrocytomas and 22 patients with high-grade astrocytomas (8-66 years of age; mean, 36 +/- 17 years) were evaluated by using a 1.5T MR imaging unit. MR imaging, PWI, DWI, and MR spectroscopy were used to determine the differences between pilocytic astrocytomas and high-grade astrocytomas. The sensitivity, specificity, and the area under the receiver operating characteristic curve of all analyzed parameters at respective cutoff values were determined. RESULTS: The relative cerebral blood volume values were significantly lower in pilocytic astrocytomas compared with the high-grade astrocytomas (1.4 +/- 0.9 versus 3.3 +/- 1.4; P = .0008). The ADC values were significantly higher in pilocytic astrocytomas compared with high-grade astrocytomas (1.5 x 10(-3) +/- 0.4 versus 1.2 x 10(-3) +/- 0.3; P = .01). The lipid-lactate in tumor/creatine in tumor ratios were significantly lower in pilocytic astrocytomas compared with high-grade astrocytomas (8.3 +/- 11.2 versus 43.3 +/- 59.2; P = .03). The threshold values >/=1.33 for relative cerebral blood volume provide sensitivity, specificity, positive predictive values, and negative predictive values of 100%, 67%, 87%, and 100%, respectively, for differentiating high-grade astrocytomas from pilocytic astrocytomas. The optimal threshold values were /=7.06 for lipid-lactate in tumor/creatine in tumor, and >/=2.11 for lipid-lactate in tumor/lipid-lactate in normal contralateral tissue. CONCLUSIONS: Lower relative cerebral blood volume and higher ADC values favor a diagnosis of pilocytic astrocytoma, while higher lipid-lactate in tumor/creatine in tumor ratios plus necrosis favor a diagnosis of high-grade astrocytomas.

BACKGROUND: Spontaneous intracranial hypotension is an uncommon clinical entity. Heritable connective tissue disorders (HCTD), such as Marfan syndrome, are frequently implicated as an underlying cause, due to dural structural weaknesses that predispose patients to spontaneous cerebrospinal fluid (CSF) leak. Due to the high prevalence of multi-system disease in HCTD, diagnosis and treatment are often complicated. CASE DESCRIPTION: We present a 58-year-old female with Marfan syndrome on anticoagulation for a mechanical aortic valve replacement who came to medical attention with severe, acute-onset headache following a straining episode. Noninvasive magnetic resonance (MR) myelography confirmed thoracic CSF extravasations and multiple lumbar diverticula. The patient was treated conservatively and her symptoms resolved. CONCLUSION: We discuss the common presentation, diagnostic tools, and treatment options for spontaneous CSF leaks in patients with Marfan syndrome or related HCTD with an emphasis on noninvasive modalities and a review of the major radiographic criteria used to diagnose dural abnormalities, such as dural ectasia.

OBJECTIVES/HYPOTHESIS: To compare the diagnostic efficacy of positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG-PET)/computed tomography (CT) to that of contrast-enhanced high-resolution CT (HRCT) and assess the value of a combinatorial approach in detection of recurrent squamous cell cancer of the head and neck (HNC) and to assess the efficacy of FDG-PET/CT with and without HRCT in comparison to standard-of-care follow-up-physical examination (PE) and endoscopy (E)-in determination of locally recurrent HNC. STUDY DESIGN: Retrospective study. METHODS: A total of 103 patients with HNC underwent FDG-PET/CT and neck HRCT. There were two groups of patients: Group A had an FDG-PET study acquired with low-dose CT, and group B had an FDG-PET study acquired with HRCT. The PET data obtained with or without HRCT were compared on a lesion and patient basis with the results of the PE/E. RESULTS: On a lesion basis, both groups combined had higher sensitivity and negative predictive value (NPV) than the HRCT. Specificity and positive predictive value (PPV) for group B were higher than for group A. On a patient basis, both groups combined had a higher sensitivity and NPV than PE/E, respectively, although specificity of PE/E was higher than that of either group. PET data obtained with either protocol directly influenced treatment. CONCLUSIONS: HRCT increases the specificity and PPV of PET/CT when acquired simultaneously with PET. FDG-PET/CT acquired with either LDCT or HRCT has higher accuracy than HRCT alone and increases the sensitivity and NPV of PE/E. LEVEL OF EVIDENCE: 4 Laryngoscope, 2013.

Ganglioneuromas are uncommon, benign, and highly differentiated tumors arising from sympathetic ganglia. Common sites for these tumors include the paraspinal region of the retroperitoneum and posterior mediastinum. We report a case of a retropharyngeal ganglioneuroma, a rare occurrence, emphasizing its key imaging characteristics.

BACKGROUND AND PURPOSE: Trigeminal nerve injury or dysfunction is associated with denervation atrophy of muscles innervated by the mandibular branch of the trigeminal nerve. The purpose of our study was to evaluate the association between chronic CN V denervation and parotid gland atrophy. MATERIALS AND METHODS: Twenty-six patients with chronic masticator muscle atrophy were retrospectively identified and evaluated for the presence of ipsilateral parotid gland atrophy. Twenty-six age-matched control subjects with no clinical or imaging evidence of chronic masticator space atrophy were also identified. Segmentation of the parotid gland was performed to calculate a parotid asymmetry index. The Fisher exact test and t test were respectively used to determine the correlation between parotid gland atrophy and ipsilateral masticator muscle atrophy and to evaluate any difference in the size of the involved parotid gland when compared with that in the control subjects. RESULTS: Ipsilateral parotid gland atrophy was seen in 9/26 (42.8%) patients with fatty replacement of the masticator group of muscles, suggesting a correlation between parotid gland atrophy and CN V denervation (P < .001). The parotid asymmetry index was significantly different in patients with CN V denervation (0.59 +/- 0.25) compared with control subjects (0.92 +/- 0.03) (P < .001). CONCLUSIONS: Ipsilateral parotid gland atrophy can accompany chronic CN V denervation change, and its clinical significance remains to be determined.