CT versus MR: still a tough decision

Development of an evaluation and treatment strategy for olfactory neuroblastoma: a review of evidence from large-scale studies, including population-based and multicenter studies, and meta-analyses

Olfactory neuroblastoma is a rare sinonasal malignancy arising from the olfactory epithelium that is characterized by skull base involvement and a modest natural history. Because of its rarity and long course, identification of independent prognostic factors is dependent on multivariate analysis of large, long-term data. In this review, we outline evidence for the evaluation and treatment of olfactory neuroblastoma obtained from recent large-scale population-based studies, meta-analyses and multicenter studies. Hyams grade is currently the only pathological grade system for olfactory neuroblastoma. The modified Kadish staging and Dulguerov classification are available for clinical staging. The results of large-scale studies have confirmed Hyams, the modified Kadish and Dulguerov as independent prognostic factors. Surgery followed by radiotherapy provides the best overall survival and recurrence-free survival for resectable disease. The question of whether postoperative radiotherapy should be administered for all cases or only for those at risk of recurrence remains unanswered. Exclusively endoscopic resection is indicated for modified Kadish A/B cases without any increase in the risk of death or recurrence, and is also indicated for modified Kadish C cases if a negative surgical margin is ensured. For more advanced cases, such as those with extensive brain infiltration, the open approach is indicated. Elective nodal irradiation prevents late nodal recurrence of N0 patients. Chemotherapy has failed to show a benefit in survival or disease control. Current needs for olfactory neuroblastoma include the development and validation of refined staging systems suitable for current practice; expansion of indications for endoscopic surgery; less invasive surgery; definitive radiotherapy and novel systemic therapy.

Segmentation-Based Fusion of CT and MR Images

In this paper, a segmentation-based image fusion method is proposed for the fusion of MR and CT images to obtain a high contrast fused image that contains complementary information from both input images. The proposed method uses the fuzzy C-mean method to extract information about the skull from the CT image. This skull information is used to extract soft tissue information from the MR image. Both the skull information and the soft tissue information are then fused using the fusion rule. The efficiency of the proposed method over other state-of-the-art fusion methods is analyzed and compared using qualitative and quantitative analysis methods. Qualitative analysis shows the improvement in the contrast between the bone and the soft tissue using the proposed method over other state-of-the-art methods without introducing any artifacts or distortions. Classical and gradient-based quantitative analysis also show significant improvement in the fused image obtained using the proposed method over the five state-of-the-art methods. The percentage improvement in the standard deviation, average gradient, entropy, spatial frequency, QABF, and LABF of the proposed method over the best value obtained by the five state-of-the-art methods is 27.11%, 12.06%, 23.64%, 11.30%, 5.59%, and 13.70% respectively.

Diagnostic performance of dynamic volume perfusion CT for differentiation of head and neck cancer from healthy tissue and post-therapeutic changes

BACKGROUND

Post-therapeutic tissue is bradytrophic and thus has low perfusion values in PCT. In contrast, malignant tissue is expected to show higher perfusion values as cancer growth partially depends on angiogenesis.

OBJECTIVES

This prospective study investigates perfusion computed tomography (PCT) for the post-therapeutic detection of cancer in the head and neck region.

METHODS

85 patients underwent PCT for 1) initial work-up of head and neck cancer (HNC; n=22) or 2) for follow-up (n=63). Regions of interest (ROIs) were placed in confirmed tumour, a corresponding location of benign tissue, and reference tissue. Perfusion was calculated using a single input maximum slope algorithm. Statistical analysis was performed with the Mann-Whitney U-test.

RESULTS

PCT allowed significant differentiation of malignant tissue from post-therapeutic tissue after treatment for HNC (p=0.018). Significance was even greater after normalization of perfusion values (p=0.007). PCT allowed highly significant differentiation of HNC from reference tissue (p<0.001).

CONCLUSIONS

PCT provides significantly distinct perfusion values for malignant and benign as well as post-therapeutically altered tissue in the head and neck area, thus allowing differentiation of cancer from healthy tissue. Our results show that PCT in conjunction with a standard algorithm is a potentially powerful HNC diagnostic tool.

PET/MR Outperforms PET/CT in Suspected Occult Tumors

BACKGROUND

To compare the diagnostic accuracy of PET/MR and PET/CT in patients with suspected occult primary tumors.

METHODS

This prospective study was approved by the institutional review board. Sequential PET/CT-MR was performed in 43 patients (22 male subjects; median age, 58 years; range, 20-86 years) referred for suspected occult primary tumors. Patients were assessed with PET/CT and PET/MR for the presence of a primary tumor, lymph node metastases, and distant metastases. Wilcoxon signed-rank test was performed to compare the diagnostic accuracy of PET/CT and PET/MR.

RESULT

According to the standard of reference, a primary lesion was found in 14 patients. In 16 patients, the primary lesion remained occult. In the remaining 13 patients, lesions proved to be benign. PET/MR was superior to PET/CT for primary tumor detection (sensitivity/specificity, 0.85/0.97 vs 0.69/0.73; P = 0.020) and comparable to PET/CT for the detection of lymph node metastases (sensitivity/specificity, 0.93/1.00 vs 0.93/0.93; P = 0.157) and distant metastases (sensitivity/specificity, 1.00/0.97 vs 0.82/1.00; P = 0.564). PET/CT tended to misclassify physiologic FDG uptake as malignancy compared with PET/MR (8 patients vs 1 patient).

CONCLUSIONS

PET/MR outperforms PET/CT in the workup of suspected occult malignancies. PET/MR may replace PET/CT to improve clinical workflow.

Imaging Characteristics of Olfactory Neuroblastoma (Esthesioneuroblastoma)

This presentation outlines the clinical and imaging characteristics of esthesioneuroblastoma.

Adult Horner's syndrome: a combined clinical, pharmacological, and imaging algorithm

The diagnosis of Horner's syndrome (HS) can be difficult, as patients rarely present with the classic triad of ptosis, miosis, and anhydrosis. Frequently, there are no associated symptoms to help determine or localise the underlying pathology. The onset of anisocoria may also be uncertain, with many cases referred after incidental discovery on routine optometric assessment. Although the textbooks discuss the use of cocaine, apraclonidine, and hydroxyamphetamine to diagnose and localise HS, in addition to reported false positive and negative results, these pharmacological agents are rarely available during acute assessment or in general ophthalmic departments. Typically, a week is required between using cocaine or apraclonidine for diagnosis and localisation of HS with hydroxyamphetamine, leaving the clinician with the decision of which investigations to request and with what urgency. Modern imaging modalities have advanced significantly and become more readily available since many of the established management algorithms were written. We thus propose a practical and safe combined clinical and radiological diagnostic protocol for HS that can be applied in most clinical settings.

Patterns of regional spread for esthesioneuroblastoma

BACKGROUND AND PURPOSE

ENB is a rare malignant neoplasm that affects the anterior skull base. Disease stage is a significant predictor of survival, in particular the presence or absence of lymph node metastases. Multiple studies have identified the cervical lymph nodes as the most frequent site of spread; however, no studies have attempted to characterize the radiographic appearance of metastatic lymph nodes or identify the primary nodal drainage for these tumors.

MATERIALS AND METHODS

We retrospectively reviewed the medical records and imaging examinations of patients with a pathologically proved diagnosis of ENB from a single tertiary care institution from 2004 to 2010. A head and neck radiologist with 9 years of experience in evaluating ENB reviewed the imaging of all patients with lymph node metastases to confirm the lymph node findings.

RESULTS

Spread of ENB to cervical lymph nodes was discovered in 14/48 patients (29%). Of the 14 patients, 5 (36%) were discovered to have lymph node involvement at initial staging, while 9 (64%) showed development of disease in the cervical nodes on surveillance examinations. Level II lymph nodes were the most frequently involved (13/14 cases). Levels I (57%) and III (50%) nodes and RPNs (43%) were also frequently involved. Metastatic lymph nodes were predominantly solid and demonstrated marked contrast enhancement, often approaching the degree of enhancement of nearby blood vessels. Metastatic nodes were moderately or highly FDG-avid.

CONCLUSIONS

ENB exhibits a predictable pattern of metastasis to cervical lymph nodes, typically spreading first to level II nodes, with frequent involvement of level I and III nodes and RPNs. Metastatic lymph nodes have characteristic imaging features that can assist radiologists in the identification of nodal disease.

Radiologic appearance of chronic parapharyngeal Teflon granuloma

Although Teflon has been used for almost 5 decades to provide tissue augmentation in various surgical indications, including head and neck surgery, its use has significantly declined in the last 2 decades, primarily because of its implication in granuloma formation. Teflon granulomas have been shown to cause false positives on positron emission tomography imaging and have been reported to have a characteristic magnetic resonance imaging (MRI) appearance. We report a patient with a large chronic Teflon granuloma of the parapharyngeal space that caused significant bony erosion of the atlas vertebra. The lesion's MRI signal characteristics were indistinguishable from those of surrounding tissues, while it showed characteristic hyperdensity on computed tomography due to the presence of fluorine atoms within Teflon. As MRI may supersede or replace computed tomography for a number of indications, and as Teflon has been used in large numbers of patients whose records may not always be available, knowledge of these findings has clinical relevance.

Diffusion-weighted imaging in head and neck cancers

This article reviews the utility of diffusion-weighted imaging (DWI) in the diagnosis, prognosis and monitoring of treatment response in tumors arising in the head and neck region. The apparent diffusion coefficient (ADC) value, determined from DWI, can help in cancer staging and detection of subcentimeter nodal metastasis. The ADC value also discriminates carcinomas from lymphomas, benign lesions from malignant tumors and tumor necrosis from abscesses. Low pretreatment ADC values typically predict a favorable response to chemoradiation therapy. These promising reports indicate the potential of DWI as a potential biomarker for diagnosis and monitoring of treatment response in head and neck cancers. In view of the overlapping ADC values between different salivary gland tumors, care should be taken when interpreting these results and other imaging parameters should be considered for a better diagnosis. Susceptibility and motion-induced artifacts may sometimes degrade DWI image quality; however, novel techniques are being developed to overcome these drawbacks.