Imaging criteria to predict Shamblin group in carotid body tumors - revisited

Prevalence, characteristics, evaluation, and management of carotid body tumors: Systematic analysis based on available evidence

OBJECTIVE

Although carotid body tumors (CBTs) are rare, they attract particular attention because of their propensity for malignant transformation and the high surgical risk. Because data are scarce and as it is difficult to achieve a large sample size, no study has yet comprehensively analyzed the characteristics, management, or operative complications of CBTs. Therefore, we collected and analyzed all currently available information on CBTs and used the pooled data to derive quantitative information on disease characteristics and management.

METHODS

We systematically searched PubMed, Embase, the Cochrane Library, and the Web of Science up to December 1, 2022, for studies that investigated the characteristics and management of CBTs. The primary objective was to identify the prevalence of the various characteristics and the incidence of complications. The secondary objective was to compare patients who underwent preoperative embolization (PE) and those who did not (non-PE), as well as to compare patients with different Shamblin grades and those with and without succinate dehydrogenase (SDH) mutations in terms of CBT characteristics and complications. Two reviewers selected studies for inclusion and independently extracted data. All statistical analyses were performed using the standard statistical procedures of Review Manager 5.2 and Stata 12.0.

RESULTS

A total of 155 studies with 9291 patients and 9862 tumors were identified. The pooled results indicated that the median age of patients with CBT was 45.72 years, and 65% were female. The proportion of patients with bilateral lesions was 13%. In addition, 16% of patients had relevant family histories, and the proportion of those with SDH gene mutations was 36%. Sixteen percent of patients experienced multiple paragangliomas, and 12% of CBTs had catecholamine function. The incidence of cranial nerve injury (CNI) was 27%, and 14% of patients suffered from permanent CNI. The incidence rates of operative mortality and stroke were both 1%, and 4% of patients developed transient ischemic attacks. Of all CBTs, 6% were malignant or associated with metastases or recurrences. The most common metastatic locations were the lymph nodes (3%) and bone (3%), followed by the lungs (2%). Compared with non-PE, PE reduced the estimated blood loss (standardized mean difference, -0.95; 95% confidence interval [CI], -1.70 to -0.20) and the operation time (standardized mean difference, -0.56; 95% CI, -1.03 to -0.09), but it increased the incidence of stroke (odds ratio, 2.44; 95% CI, 1.04-5.73). Higher Shamblin grade tumors were associated with more operative complications. Patients who were SDH gene mutation-positive were more likely to have a relevant family history and had more symptoms.

CONCLUSIONS

CBT was most common in middle-aged females, and early surgical resection was feasible; there was a low incidence of serious operative complications. Routine PE is not recommended because this may increase the incidence of stroke, although PE somewhat reduced the estimated blood loss and operation time. Higher Shamblin grade tumors increased the incidence of operative complications. Patients who were SDH gene mutation-positive had the most relevant family histories and symptoms.

Current management of carotid body tumors

Carotid body tumors (CBTs) are neoplasms that occur at the bifurcation of the carotid artery and are pathologically classified as paragangliomas. In the 4th edition of the WHO classification, paragangliomas are categorized as neoplasms with malignant potential. Clinically, about 5% of CBTs present with malignant features such as metastasis. Currently, it is challenging to distinguish between tumors with benign courses and those that present malignantly. Recent advances in genetic testing have elucidated the genetic characteristics of paragangliomas, including carotid body tumors. Over 20 genes have been identified as being involved in tumor development. Particularly in head and neck paragangliomas, abnormalities in genes related to succinate dehydrogenase are frequently observed. Research is ongoing to understand the mechanisms by which these genes contribute to tumor development. The definitive treatment for CBTs is surgical resection. These tumors are prone to bleeding and often adhere firmly to the carotid artery, making intraoperative bleeding control challenging. The risk of lower cranial nerve paralysis is relatively high, and there is a risk of stroke because of manipulation of the carotid artery. Preoperative evaluation with angiography is essential, and a multi-disciplinary surgical team approach is necessary. In cases where the tumor is difficult to resect or has metastasized, radiation therapy or chemotherapy are employed. Clinical trials involving targeted molecular therapies and radiopharmaceuticals have recently been conducted, with some applied clinically. The development of various new treatments is anticipated, providing hope for therapeutic options in refractory cases.

MR imaging-based risk stratification scoring system to predict clinical outcomes in carotid body tumors

Objectives

This study aims to evaluate the role of pretherapy MRI in predicting outcomes in carotid body tumors and propose a grading system for high- and low-risk characteristics.

Materials and methods

A retrospective observational study of 44 patients with 51 lesions was carried out from year 2005 to 2020. MR images were reviewed for characteristics of carotid body tumor, and a score was given that was correlated with intra- and postoperative findings. The various other classifications and our proposed Mahajan classification were compared with Shamblin's classification. The area under the curve and ROC curves were used to present the accuracy of different predictive models.

Results

Our scoring system allotted a score of 0 to 15 on the basis of MRI characteristics, with scores calculated for patients in our study ranging from 0 to 13. Lesions with scores of 0-6 were considered low risk (45%), and scores of 7-15 were regarded as high risk for surgery (55%). The Mahajan classification stages tumors into four grades: I (10%), II (20%), IIIa (8%), and IIIb (62%). The frequency of vascular injury was 50% in category I and 64% in category IIIb. The frequency of cranial nerve injury was 50%, 66%, and 27% in categories I, II, and IIIb.

Conclusion

The Mahajan classification of CBTs evaluates high-risk factors like the distance of the tumor from the skull base and the angle of contact with ICA, which form the major predictors of neurovascular damage and morbidity associated with its surgery. Though the Shamblin classification of CBT is the most widely accepted classification, our proposed Mahajan classification system provides an imaging-based alternative to prognosticate surgical candidates preoperatively.

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.

The Role of CT Angiography to Predict the Shamblin Group in Carotid Body Tumors

Carotid body tumors (CBTs) are uncommon benign head and neck neoplasms. Surgical resection is the treatment of choice for CBTs. However, the anatomical structures adjacent to the tumor tissue may encounter serious injuries during the surgery. Shamblin grading system is a surgical intra-operative scoring system to determine the risks associated with the surgery. Therefore, we aimed to evaluate the correlation of pre-surgical imaging parameters with Shamblin grades and intra-operative complications. In this cross sectional study, we enrolled 36 patients with CBTs. Preoperative cervical CT angiography was acquired in each participant and following parameters were reported in each case: Tumor volume, tumor distance to the base of the skull (TDBS), tumor contact with the internal carotid artery (ICA), and external carotid artery (ECA) and tumor density. Finally, we assessed the relation of pre-surgical imaging parameters with Shamblin grades, and intra-operative complications. Only tumor volume was significantly correlated with Shamblin grades (P < 0.05). The tumor contact with ECA was marginally correlated with Shamblin grades (P = 0.103); however, other imaging parameters were not significantly correlating with Shamblin grades. There was a statistically significant correlation between ICA contact and tumor volume with ECA injury. In addition, the tumor density significantly correlated with cranial nerves injury. The results of STATA analysis were indicative for 69.44% accordance between radiologic typing and Shamblin grading system. We found that tumor volume correlates significantly with Shamblin grading system, and there is significant correlation between tumor ICA contact, and tumor density and intra-operative complications.

Application of the shear wave elastography in the assessment of carotid body tumors: A preliminary study

Objectives

To evaluate the elasticity of carotid body tumors (CBTs) by two-dimensional shear wave elastography (SWE).

Methods

22 pathologically or clinically confirmed CBTs in 16 patients were scanned by SWE. The maximum elasticity value (Emax) and its standard deviation (SDmax) in kPa and m/s for CBTs were obtained by placing a round ROI (2-3 mm) on the stiffest region of the CBTs. Elasticity value was compared between hard and soft groups at manual palpation, benign and malignant groups and among three Shamblin types. The area under the receiver operating characteristic curve (AUC) analysis was performed to evaluate the performance of SWE in the malignancy prediction of CBTs. Sensitivity, specificity and accuracy were calculated. The cut-off value was obtained by using the Youden index.

Results

There were 19 benign CBTs and 3 malignant CBTs. Emax (kPa and m/s) and SDmax (kPa) were significantly higher in the hard group than in the soft group at manual palpation (P<0.05); The distribution of Emax in kPa and m/s and SDmax in kPa were different in the three Shamblin types (P<0.05), Emax (kPa and m/s)increased from shambling I to Shambling II and Shambling III; Emax (kPa and m/s) were significantly higher in the malignant CBTs than in the benign ones (P<0.05). Emax in kPa and m/s had the similar AUC value (AUC=0.947, P=1.0000) for the prediction of malignant CBTs. Emax in kPa with the cut-off 124.9kPa showed a sensitivity of 100.0%, specificity of 94.7%, and an accuracy of 95.5% (Z=8.500, P<0.0001); Emax in m/s with the cut-off 5.9m/s showed a sensitivity of 100.0%, specificity of 89.5% and an accuracy of 90.9% for the prediction of malignant CBTs (Z=9.143, P<0.0001).

Conclusions

Quantitative analysis of SWE obtained the good performance in the elasticity assessment of CBTs.

A new potential risk factor for permanent cranial nerve injury following carotid body tumor resection

Background

To quantify the association between the free distal segment length of the internal carotid artery (FDS-ICA) and permanent cranial nerve injury (p-CNI) following carotid body tumor (CBT) resection.

Methods

This study is a case-control study. We surveyed 109 consecutive patients who underwent CBT resection between June 2015 and June 2020 at our single center. A total of 89 patients met the inclusion criteria and were selected for analysis. The FDS-ICA was measured by image post-processing software for computed tomography angiography (CTA). Postoperative p-CNI complications were evaluated using comprehensive statistical approaches.

Results

The cohort was divided into 2 groups depending on the presence of p-CNI, namely the p-CNI group (n=17) and the non-CNI group (n=79). The average FDS-ICA of patients with p-CNI complications was shorter than that of those without p-CNI complications (P<0.001). For every 1 mm increase in FDS-ICA, there was an associated decrease of 8% in the risk of p-CNI (0.92, 95% CI: 0.85 to 0.98, P<0.05). Threshold effect analysis of the FDS-ICA on p-CNI identified that the FDS-ICA was 28.7 (95% CI: 23.8 to 30.9) mm.

Conclusions

The results of this study revealed a significant independent association between FDS-ICA and permanent postoperative cranial nerve injury complications of CBTs. Further study is warranted to confirm these results in a larger patient cohort.