Head and neck paragangliomas: diffusion weighted and dynamic contrast enhanced magnetic resonance imaging characteristics

[French recommendations for malignant pheochromocytomas and paragangliomas by the national ENDOCAN-COMETE network]

Pheochromocytomas and paragangliomas are rare neuroendocrine tumors, developed respectively in the adrenal medulla and in extra-adrenal locations. Their malignancy is defined by the presence of distant metastases. Forty percent of them are inherited and can be part of different hereditary syndromes. Their management is ensured in France by the multidisciplinary expert centers of the ENDOCAN-COMETE national network "Cancers of the Adrenal gland", certified by the National Cancer Institute and discussed within multidisciplinary team meetings. The diagnostic and therapeutic work-up must be standardized, based on an expert analysis of clinical symptoms, hormonal biological secretions, genetics, morphological and specific metabolic imaging. In the context of a heterogeneous survival sometimes beyond seven to ten years, therapeutic intervention must be justified. This is multidisciplinary and relies on surgery, interventional radiology, external or internal radiotherapy and medical treatments such as sunitinib or dacarbazine and temodal chemotherapy. The personalized approach based on functional imaging fixation status and genetics is progressing despite the extreme rarity of this disease.

Image-Guided Precision Medicine in the Diagnosis and Treatment of Pheochromocytomas and Paragangliomas

In this comprehensive review, we aimed to discuss the current state-of-the-art medical imaging for pheochromocytomas and paragangliomas (PPGLs) diagnosis and treatment. Despite major medical improvements, PPGLs, as with other neuroendocrine tumors (NETs), leave clinicians facing several challenges; their inherent particularities and their diagnosis and treatment pose several challenges for clinicians due to their inherent complexity, and they require management by multidisciplinary teams. The conventional concepts of medical imaging are currently undergoing a paradigm shift, thanks to developments in radiomic and metabolic imaging. However, despite active research, clinical relevance of these new parameters remains unclear, and further multicentric studies are needed in order to validate and increase widespread use and integration in clinical routine. Use of AI in PPGLs may detect changes in tumor phenotype that precede classical medical imaging biomarkers, such as shape, texture, and size. Since PPGLs are rare, slow-growing, and heterogeneous, multicentric collaboration will be necessary to have enough data in order to develop new PPGL biomarkers. In this nonsystematic review, our aim is to present an exhaustive pedagogical tool based on real-world cases, dedicated to physicians dealing with PPGLs, augmented by perspectives of artificial intelligence and big data.

Carotid body paraganglioma: a case report

A highly vascular glomus tumor that develops from the paraganglion cells of the carotid body is called a carotid body tumor (CBT), also known as a chemodectoma or carotid body paraganglioma (CBP). It is situated near the carotid bifurcation, where the external and internal carotid arteries splay out characteristically. We present a case of a 30-year-old woman who had a slightly tender, slightly pulsatile, and slightly ballotable swelling over the lateral aspect of the neck on the right side. The surgical resection of the tumor was done based on the diagnosis made on clinical-radiological investigations as a carotid body tumor further confirmed by a histopathological study. We also provide a summary of the research on carotid body tumors clinical and imaging manifestations, assessment, and therapy.

New and Advanced Magnetic Resonance Imaging Diagnostic Imaging Techniques in the Evaluation of Cranial Nerves and the Skull Base

The skull base and cranial nerves are technically challenging to evaluate using magnetic resonance (MR) imaging, owing to a combination of anatomic complexity and artifacts. However, improvements in hardware, software and sequence development seek to address these challenges. This section will discuss cranial nerve imaging, with particular attention to the techniques, applications and limitations of MR neurography, diffusion tensor imaging and tractography. Advanced MR imaging techniques for skull base pathology will also be discussed, including diffusion-weighted imaging, perfusion and permeability imaging, with a particular focus on practical applications.

Diagnostic Role of Diffusion-Weighted and Dynamic Contrast-Enhanced Perfusion MR Imaging in Paragangliomas and Schwannomas in the Head and Neck

BACKGROUND AND PURPOSE

Distinguishing schwannomas from paragangliomas in the head and neck and determining succinate dehydrogenase (SDH) mutation status in paragangliomas are clinically important. We aimed to assess the clinical usefulness of DWI and dynamic contrast-enhanced MR imaging in differentiating these 2 types of tumors, as well as the SDH mutation status of paragangliomas.

MATERIALS AND METHODS

This retrospective study from June 2016 to June 2020 included 42 patients with 15 schwannomas and 27 paragangliomas (10 SDH mutation-positive and 17 SDH mutation-negative). ADC values, dynamic contrast-enhanced MRI parameters, and tumor imaging characteristics were compared between the 2 tumors and between the mutation statuses of paragangliomas as appropriate. Multivariate stepwise logistic regression analysis was performed to identify significant differences in these parameters.

RESULTS

Fractional plasma volume (P ≤ .001), rate transfer constant (P = .038), time-to-maximum enhancement (P < .001), maximum signal-enhancement ratio (P < .001) and maximum concentration of contrast agent (P < .001), velocity of enhancement (P = .002), and tumor characteristics including the presence of flow voids (P = .001) and enhancement patterns (P = .027) showed significant differences between schwannomas and paragangliomas, though there was no significant difference in ADC values. In the multivariate logistic regression analysis, fractional plasma volume was identified as the most significant value for differentiation of the 2 tumor types (P = .014). ADC values were significantly higher in nonhereditary than in hereditary paragangliomas, while there was no difference in dynamic contrast-enhanced MR imaging parameters.

CONCLUSIONS

Dynamic contrast-enhanced MR imaging parameters show promise in differentiating head and neck schwannomas and paragangliomas, while DWI can be useful in detecting SDH mutation status in paragangliomas.

Assessment of MR Imaging and CT in Differentiating Hereditary and Nonhereditary Paragangliomas

BACKGROUND AND PURPOSE

Head and neck paragangliomas have been reported to be associated with mutations of the succinate dehydrogenase enzyme family. The aim of this study was to assess whether radiologic features could differentiate between paragangliomas in the head and neck positive and negative for the succinate dehydrogenase mutation.

MATERIALS AND METHODS

This single-center retrospective review from January 2015 to January 2020 included 40 patients with 48 paragangliomas (30 tumors positive for succinate dehydrogenase mutation in 23 patients and 18 tumors negative for the succinate dehydrogenase mutation in 17 patients). ADC values and tumor characteristics on CT and MR imaging were evaluated by 2 radiologists. Differences between the 2 cohorts in the diagnostic performance of ADC and normalized ADC (ratio to ADC in the medulla oblongata) values were evaluated using the independent samples t test. P < .05 was considered significant.

RESULTS

ADC_mean (1.07 [SD, 0.25]/1.04 [SD, 0.12] versus 1.31 [SD, 0.16]/1.30 [SD, 0.20]× 10^-3 mm²/s by radiologists 1 and 2; P < .001), ADC_maximum (1.49 [SD, 0.27]/1.49 [SD, 0.20] versus 2.01 [SD, 0.16]/1.87 [SD, 0.20] × 10^-3 mm²/s; P < .001), normalized ADC_mean (1.40 [SD, 0.33]/1.37 [SD, 0.16] versus 1.73 [SD, 0.22]/1.74 [SD, 0.27]; P < .001), and normalized ADC_maximum (1.95 [SD, 0.37]/1.97 [SD, 0.27] versus 2.64 [SD, 0.22]/2.48 [SD, 0.28]; P < .001) were significantly lower in succinate dehydrogenase mutation-positive than mutation-negative tumors. ADC_minimum, normalized ADC_minimum, and tumor characteristics were not statistically significant.

CONCLUSIONS

ADC is a promising imaging biomarker that can help differentiate succinate dehydrogenase mutation-positive from mutation-negative paragangliomas in the head and neck.

Dynamic contrast-enhanced magnetic resonance imaging for differentiating head and neck paraganglioma and schwannoma

BACKGROUND AND PURPOSE

Morphological assessment with conventional magnetic resonance imaging (MRI) sequences has limited specificity to distinguish between paragangliomas and schwannomas. Assessing the differences in microvascular properties through pharmacokinetic parameters of dynamic contrast-enhanced (DCE)-MRI can provide additional information to aid in this differentiation.

MATERIALS AND METHODS

A prospective study on MR characterization of neck masses was performed between January 2017 and March 2019 in our department, out of which 40 patients with head and neck paragangliomas (HNPGLs) (33 lesions) and schwannomas (15 lesions) were included in this analysis. MR perfusion using dynamic axial T1WI fat suppressed fast spoiled gradient recalled sequence with parallel imaging was performed in all the patients, in addition to single-shot turbo spin-echo axial diffusion weighted imaging (DWI) and routine MRI. ROI-based method was used to obtain signal-time curves, permeability measurements, and mean apparent diffusion coefficient (ADC) to differentiate paragangliomas from schwannomas. Statistical analysis was done to assess the significance and establish a cutoff to distinguish between the two entities. The available images of DOTANOC PET/CT (34 lesions) were analyzed retrospectively. Correlations between the perfusion, diffusion, and molecular PET/CT parameters were done.

RESULTS

Paragangliomas had a higher wash-in rate, wash-out rate, K_trans, K_ep , and V_p (p < 0.001); while schwannomas had a higher relative enhancement (p < 0.012), time to peak, time of onset, brevity of enhancement, and V_e (p < 0.001). Among the perfusion parameters, K_ep (area under curve (AUC) 0.994) and V_p (AUC 0.992) were found to have the highest diagnostic value. In diffusion-weighted imaging, paragangliomas had a lower mean ADC compared to schwannomas (p < 0.001). The SUV_max and SUV_mean were significantly associated with K_trans , K_ep , and V_p in paragangliomas.

CONCLUSION

DCE-MRI in addition to DWI-MRI can accurately distinguish HNPGL from schwannoma and may replace the need for any additional imaging and preoperative biopsy in most cases.

Management of Multiple Head and Neck Paragangliomas With Assistance of a 3-D Model

INTRODUCTION

Extirpation of multiple head and neck paragangliomas carries challenge due to close anatomic relationships with critical neurovascular bundles.

OBJECTIVES

This study aims to assess whether the application of 3-D models can assist with surgical planning and treatment of these paragangliomas, decrease surgically related morbidity and mortality.

METHODS

Fourteen patients undergoing surgical resection of multiple head and neck paragangliomas were enrolled in this study. A preoperative 3-D model was created based on radiologic data, and relevant critical anatomic relationships were preoperatively assessed and intraoperatively validated.

RESULTS

All 14 patients presented with multiple head and neck paragangliomas, including bilateral carotid body tumors (CBT, n = 9), concurrent CBT with glomus jugulare tumors (GJT, n = 4), and multiple vagal paragangliomas (n = 1). Ten patients underwent genomic analysis and all harbored succinate dehydrogenase complex subunit D (SDHD) mutations. Under guidance of the 3-D model, the internal carotid artery (ICA) was circumferentially encased by tumor on 5 of the operated sides, in 4 (80%) of which the tumor was successfully dissected out from the ICA, whereas ICA reconstruction was required on one side (20%). Following removal of CBT, anterior rerouting of the facial nerve was avoided in 3 (75%) of 4 patients during the extirpation of GJT with assistance of a 3-D model. Two patients developed permanent postoperative vocal cord paralysis. There was no vessel rupture or mortality in this study cohort.

CONCLUSION

The 3-D model is beneficial for establishment of a preoperative strategy, as well as planning and guiding the intraoperative procedure for resection of multiple head and neck paragangliomas.

Solitary neurofibroma of the larynx: a diagnostic challenge

Solitary neurofibromas of the larynx are extremely rare, with a total of 15 cases described in the literature. Nonetheless, acquaintance with this diagnosis is important, as misdiagnoses can have negative consequences. Presenting symptoms are non-specific and depend on tumour size and location. As well-defined submucosal masses with a broad differential diagnosis, they remain a clinical and radiological challenge. While some characteristics might favour a benign nature and subtle signs might help narrow the differential diagnosis, imaging alone is not sufficient for differentiation and definitive diagnosis requires a biopsy. Complete surgical resection and long-term follow-up is indicated. We share our experience on a case of a solitary laryngeal neurofibroma in a middle-aged woman, presenting with a large well-defined paraglottic lesion.

Achieving high spatial and temporal resolution with perfusion MRI in the head and neck region using golden-angle radial sampling

Objectives

Conventional perfusion-weighted MRI sequences often provide poor spatial or temporal resolution. We aimed to overcome this problem in head and neck protocols using a golden-angle radial sparse parallel (GRASP) sequence.

Methods

We prospectively included 58 patients for examination on a 3.0-T MRI using a study protocol. GRASP (A) was applied to a volumetric interpolated breath-hold examination (VIBE) with 135 reconstructed pictures and high temporal (2.5 s) and spatial resolution (0.94 × 0.94 × 3.00 mm). Additional sequences of matching temporal resolution (B: 2.5 s, 1.88 × 1.88 × 3.00 mm), with a compromise between temporal and spatial resolution (C: 7.0 s, 1.30 × 1.30 × 3.00 mm) and with matching spatial resolution (D: 145 s, 0.94 × 0.94 × 3.00 mm), were subsequently without GRASP. Instant inline-image reconstructions (E) provided one additional series of averaged contrast information throughout the entire acquisition duration of A. Overall diagnostic image quality, edge sharpness and contrast of soft tissues, vessels and lesions were subjectively rated using 5-point Likert scales. Objective image quality was measured as contrast-to-noise ratio in D and E.

Results

Overall, the anatomic and pathologic image quality was substantially better with the GRASP sequence for the temporally (A/B/C, all p < 0.001) and spatially resolved comparisons (D/E, all p < 0.002 except lesion edge sharpness with p = 0.291). Image artefacts were also less likely to occur with GRASP. Differences in motion, aliasing and truncation were mainly significant, but pulsation and fat suppression were comparable. In addition, the contrast-to-noise ratio of E was significantly better than that of D (p_D-E < 0.001).

Conclusions

High temporal and spatial resolution can be obtained synchronously using a GRASP-VIBE technique for perfusion evaluation in head and neck MRI.

Key Points

• Golden-angle radial sparse parallel (GRASP) sampling allows for temporally resolved dynamic acquisitions with a very high image quality.

• Very low-contrast structures in the head and neck region can benefit from using the GRASP sequence.

• Inline-image reconstruction of dynamic and static series from one single acquisition can replace the conventional combination of two acquisitions, thereby saving examination time.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-07263-0) contains supplementary material, which is available to authorized users.

Texture analysis of routine T2 weighted fat-saturated images can identify head and neck paragangliomas - A pilot study

PURPOSE

To evaluate the role of the first and second-order texture parameters obtained from T2-weighted fat-saturated DIXON images in differentiating paragangliomas from other neck masses, and to develop a statistical model to classify them.

METHOD

We retrospectively evaluated 38 paragangliomas, 18 nerve-sheath tumours and 14 other miscellaneous neck lesions obtained from an IRB approved study conducted between January 2016 and June 2019; using a composite gold standard of histopathology, cytology and DOTANOC PET CT (A total of 70 lesions in 63 patients). Fat-suppressed T2weighted-DIXON axial images were used. First and second-order texture-parameters were calculated from the original and filtered images. Feature selection using F-statistics and collinearity analysis provided 14 texture parameters for further analysis. Mann-Whitney-U test was used to compare between the groups and p-values were adjusted for multiple comparisons. ROC curve analysis was used to obtain optimal cut-offs.

RESULTS

A total of ten texture features were found to be significantly different between paragangliomas and non-paraganglioma lesions. Minimum from the histogram of grey levels was lower in paragangliomas with a cut off of ≤113.462 obtaining 62.9 % sensitivity and 77.27 % specificity in differentiating paragangliomas from non-paragangliomas. Logistic regression model was trained (n-49) using forward feature selection, which when evaluated on the validation set(n-21)- obtained an AUC of 0.855(95 %CI, 0.633 to 0.968) with a positive likelihood ratio of 4.545 (95 %CI, 1.298-15.923) in differentiating paragangliomas from non-paragangliomas.

CONCLUSION

Texture analysis of a routine imaging sequence can identify paragangliomas with high accuracy. Further development of texture analysis would enable better imaging workflow, resource utilisation and imaging cost reductions.

Apparent Diffusion Coefficient for Distinguishing Between Malignant and Benign Lesions in the Head and Neck Region: A Systematic Review and Meta-Analysis

Background: The purpose of the present meta-analysis was to provide evident data about use of apparent diffusion coefficient (ADC) values for distinguishing malignant and benign lesions in the head and neck region.

Material and Methods: MEDLINE and Scopus databases were screened for associations between ADC and malignancy/benignancy of head and neck lesions up to December 2018. Overall, 22 studies met the inclusion criteria. The following data were extracted: authors, year of publication, study design, number of patients/lesions, lesion type, mean value, and standard deviation of ADC. The primary endpoint of the systematic review was the analysis of the association between lesion nature and ADC values. The methodological quality of the involved studies was checked according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) instrument. The meta-analysis was undertaken by using RevMan 5.3 software. DerSimonian and Laird random-effects models with inverse-variance weights were used without further correction to account for the heterogeneity between the studies. Mean ADC values including 95% confidence intervals were calculated separately for benign and malignant lesions.

Results: The acquired 22 studies comprised 1,227 lesions. Different malignant lesions were diagnosed in 818 cases (66.7%) and benign lesions in 409 cases (33.3%). The mean ADC value of the malignant lesions was 1.04 × 10⁻³ mm²/s, and the mean value of the benign lesions was 1.46 × 10⁻³ mm²/s. Lymphomas and sarcomas showed the lowest calculated mean ADC values, 0.7 and 0.79 × 10⁻³ mm²/s, respectively. Adenoid cystic carcinomas had the highest ADC values (1.5 × 10⁻³ mm²/s). None of the analyzed malignant tumors had mean ADC values above 1.75 × 10⁻³ mm²/s.

Conclusion: ADC values play a limited role in distinguishing between malignant and benign lesions in the head and neck region. It may be only suggested that lesions with mean ADC values above 1.75 × 10⁻³ mm²/s are probably benign. Further large studies are needed for the analysis of the role of diffusion-weighted imaging (DWI)/ADC in the discrimination of benign and malignant lesions in the head and neck region.

Recent advances in MRI of the head and neck, skull base and cranial nerves: new and evolving sequences, analyses and clinical applications

MRI is an invaluable diagnostic tool in the investigation and management of patients with pathology of the head and neck. However, numerous technical challenges exist, owing to a combination of fine anatomical detail, complex geometry (that is subject to frequent motion) and susceptibility effects from both endogenous structures and exogenous implants. Over recent years, there have been rapid developments in several aspects of head and neck imaging including higher resolution, isotropic 3D sequences, diffusion-weighted and diffusion-tensor imaging as well as permeability and perfusion imaging. These have led to improvements in anatomic, dynamic and functional imaging. Further developments using contrast-enhanced 3D FLAIR for the delineation of endolymphatic structures and black bone imaging for osseous structures are opening new diagnostic avenues. Furthermore, technical advances in compressed sensing and metal artefact reduction have the capacity to improve imaging speed and quality, respectively. This review explores novel and evolving MRI sequences that can be employed to evaluate diseases of the head and neck, including the skull base.

Carotid body tumor: a case report and literature review

The carotid body is the largest collection of paraganglia in the head and neck and is found on the medial aspect of the carotid bifurcation bilaterally. Carotid body tumors are rare neoplasms arising from the chemoreceptor cells of the carotid bulb. We report a case of carotid body tumor in a 42-year-old female, who presented with painless, pulsatile, gradually progressive lateral neck swelling. The diagnosis is suspected on the basis of history, clinical and radiological examination findings and a successful surgical excision of the tumor is performed. Histopathological examination confirms the diagnosis of carotid body tumor. We also present brief literature about carotid body tumors in terms of its clinical and imaging presentation, evaluation, and management.

Multimodality fMRI with perfusion, diffusion-weighted MRI and 1 H-MRS in the diagnosis of lympho-associated benign and malignant lesions of the parotid gland

BACKGROUND

Differential diagnosis of the mucosa-associated lymphoid tissue lymphoma (MALToma) and tumor-like benign lymphoepithelial lesion (BLEL) in the parotid gland is difficult.

PURPOSE

To distinguish MALToma and BLEL with multimodality MRI including hydrogenproton magnetic resonance spectroscopy (¹ H-MRS), diffusion-weighted imaging (DWI-MR), and dynamic contrast-enhanced (DCE-MR), and evaluate each sequence.

STUDY TYPE

Retrospective.

POPULATION

Twenty-five patients with parotid tumor-like BLEL and 20 with parotid MALToma.

FIELD STRENGTH/SEQUENCE

1.5-T/T₁ WI, T₂ WI, single-voxel ¹ H-MRS, DWI-MR, and DCE-MR.

ASSESSMENT

All MR images were interpreted and agreed upon by two radiologists who were blinded to clinical information and histopathologic results. The imaging diagnoses were then compared to the histopathologic results.

STATISTICAL TESTS

Youden index was used to determine the optimized threshold value. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficiency of different functional (f)MRI methods.

RESULTS

Fisher's exact test indicated a significant difference between the ¹ H-MRS images of the two lesions (P < 0.001). The sensitivity, specificity, and accuracy of positive choline (Cho) peak in ¹ H-MRS of parotid MALToma were 80%, 76%, and 77.7%, respectively. The mean apparent diffusion coefficient (ADC) was 0.992 × 10^-3 mm² /s in patients with parotid tumor-like BLEL and 0.634 × 10^-3 mm² /s in patients with parotid MALToma, and the difference was statistically significant (t-test, P < 0.001). Choosing the Youden index as 0.669 × 10^-3 mm² /s, the sensitivity, specificity, and accuracy of the assay were 78.9%, 95.8%, and 88.4%, respectively. Assuming that time-intensity curve (TIC) type I indicated parotid MALToma (positive), and type II and type III indicated parotid tumor-like BLEL (negative), the sensitivity, specificity, and accuracy of time-to-peak (TTP) and initial slope of increase (ISI) in diagnosing MALToma were 94.1%, 95.2%, and 94.7%, respectively. Combining methods of TTP, ADC, and Cho peak reached the highest AUC (1.000).

DATA CONCLUSION

Combined use ¹ H-MRS, DWI-MR, and DCE-MR increased the accuracy of the differential diagnosis between these lesions to 100%. Cho peak in ¹ H-MRS, ADC less than 0.669 × 10^-3 mm² /s, TIC type I together indicated parotid MALToma.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:423-432.

MR imaging features of benign retroperitoneal paragangliomas and schwannomas

Background

To determine whether MRI feature analysis can differentiate benign retroperitoneal extra-adrenal paragangliomas and schwannomas.

Methods

The MRI features of 50 patients with confirmed benign retroperitoneal extra-adrenal paragangliomas and schwannomas were retrospectively reviewed by two radiologists blinded to the histopathologic diagnosis. These features were compared between two types of tumours by use of the Mann-Whitney test and binary logistic regression. The patients’ clinical characteristics were reviewed.

Results

Analysis of MRI images from 50 patients revealed no significant differences in the quantitative MRI features of lesion size, ratio of diameter and apparent diffusion coefficient. There were significant differences in the qualitative MRI features of location, necrosis, cysts and degree of tumour enhancement for two readers, with no significant differences in the other qualitative MRI features between these tumours. The combination of necrosis with degree of tumour enhancement during the arterial phase increased the probability that a retroperitoneal mass would represent retroperitoneal extra-adrenal paraganglioma as opposed to schwannoma.

Conclusion

We have presented the largest series of MRI features of both benign retroperitoneal extra-adrenal paragangliomas and schwannomas. Some MRI features assist in the differentiation between these tumours, with imaging features consisting of necrosis and avid enhancement during the arterial phase, suggestive of retroperitoneal extra-adrenal paragangliomas.

Diagnosis of a tympanic paraganglioma with CT perfusion imaging: a technical note and case description

Paragangliomas can be diagnosed accurately using magnetic resonance imaging and dynamic four-dimensional magnetic resonance angiography. Four-dimensional imaging uses the highly vascularised structure of these tumours, which results in a homogenous capillary blush and usually, due to the arteriovenous shunting, in an early draining vein. By these features the tumour can be differentiated from other neoplasms. The authors describe a case of a paraganglioma localised in the middle ear of an elderly patient. Magnetic resonance contraindications led to preoperative diagnostics with high resolution computed tomography of the temporal bone and additionally computed tomography perfusion imaging instead of magnetic resonance imaging with four-dimensional magnetic resonance angiography. Using the computed tomography perfusion dataset, regions of interest were placed in the carotid artery, the sigmoid sinus and the tympanic mass. In the computer-assisted analysis the tumour showed late arterial enhancement and delayed wash-out compared to the enhancement curves of the carotid artery and the sigmoid sinus. This corresponded to the highly vascularised nature of a paraganglioma. On postoperative follow-up imaging computed tomography perfusion showed almost no enhancement of a small residual tympanic mass, which was then considered to be granulation tissue. In conclusion, in the case of magnetic resonance contraindications the preoperative diagnosis of tympanic paraganglioma can be made using computed tomography imaging criteria alone. Computed tomography perfusion imaging may be helpful in these cases to detect residual or recurrent tumour.

MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extra-adrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis.

State of the art MRI in head and neck cancer

Head and neck cancer affects more than 11,000 new patients per year in the UK¹ and imaging has an important role in the diagnosis, treatment planning, and assessment, and post-treatment surveillance of these patients. The anatomical detail produced by magnetic resonance imaging (MRI) is ideally suited to staging and follow-up of primary tumours and cervical nodal metastases in the head and neck; however, anatomical images have limitations in cancer imaging and so increasingly functional-based MRI techniques, which provide molecular, metabolic, and physiological information, are being incorporated into MRI protocols. This article reviews the state of the art of these functional MRI techniques with emphasis on those that are most relevant to the current management of patients with head and neck cancer.

Metastatic Renal Cell Carcinoma Masquerading as Jugular Foramen Paraganglioma: A Role for Novel Magnetic Resonance Imaging

OBJECTIVES

To describe a case of metastatic renal cell carcinoma (RCC) masquerading as a jugular foramen paraganglioma (JP). To compare imaging findings between skull base metastatic RCC and histologically proven paraganglioma.

METHODS

A case of unexpected metastatic skull base RCC is reviewed. Computed tomography (CT) and magnetic resonance imaging (MRI) were compared between 3 confirmed cases of JP and our case of metastatic RCC. Diffusion-weighted MRI (DW-MRI) sequences and computed apparent diffusion coefficient (ADC) values were compared between these entities.

RESULTS

A 55-year-old man presents with what appears clinically and radiographically to be JP. The tumor was resected, then discovered on postoperative pathology to be metastatic RCC. Imaging was retrospectively compared between 3 histologically confirmed cases of JP and our case of skull base RCC. The RCC metastasis was indistinguishable from JP on CT and traditional MRI but distinct by ADC values calculated from DW-MRI.

CONCLUSIONS

Metastatic RCC at the skull base may mimic the clinical presentation and radiographic appearance of JP. The MRI finding of flow voids is seen in both paraganglioma and metastatic RCC. Diffusion-weighted MRI is able to distinguish these entities, highlighting its potential utility in distinguishing skull base lesions.

Morphological and functional imaging of neck paragangliomas

OBJECTIVE

To review the optimal techniques for localization and characterization of neck paragangliomas (PGL).

MATERIAL AND METHODS

Systematic review of the literature from the PubMed/Medline database.

RESULTS

Neck PGL are hypervascular tumours essentially arising from paraganglionic tissue situated at the carotid bifurcation (carotid body) and along the vagus nerve. Morphological and functional imaging are indicated to confirm the diagnosis, identify multifocal disease and for local and regional staging. MR angiography is the noninvasive technique of choice. CT scan and especially CT angiography are excellent alternatives for diagnosis and staging. Conventional arteriography remains useful preoperatively for embolization and occlusion tests. Functional imaging allows localization and characterization of PGLs. Somatostatin receptor scintigraphy (SRS) was the reference imaging technique for staging of sporadic PGLs. The indications for PET imaging have been extended over recent years in parallel with the development of new tracers such as [¹⁸F]-FDOPA PET or ⁶⁸Gallium-labelled DOTA peptides. ⁶⁸Gallium-labelled DOTA peptides has become the first-line imaging modality in the evaluation of cervical PGLs, regardless of the genetic background.

CONCLUSION

Morphological and functional imaging is essential for the staging of neck PGL.

Nasal paraganglioma: differential diagnosis from a radiologic and pathologic perspective

A 33-year-old Asian male presented with spontaneous nosebleeds and olfactory sense problems for the past several years. CT scan and MRI demonstrated a large soft tissue mass in the nasal cavity and paranasal sinus with avid and homogeneous contrast enhancement, focal osseous destruction and a non-enhancing cyst at the intracranial tumour–brain margin. After complete endonasal resection, histopathological examination revealed a paraganglioma. This case highlights the non-specific imaging features of a rare paraganglioma of the anterior skull base and the differential diagnosis from both radiological and pathological perspective.