PET/MRI vs PET/CT in Head and Neck Imaging: When, Why, and How?

[18F]FDG PET/CT versus [18F]FDG PET/MRI in the diagnosis of lymph node metastasis in nasopharyngeal carcinoma: a systematic review and meta-analysis

Purpose

This meta-analysis aimed to evaluate the comparative diagnostic accuracy of [18F]FDG PET/CT versus [18F]FDG PET/MRI in identifying lymph node metastases in individuals with nasopharyngeal carcinoma.

Methods

A comprehensive search was executed across PubMed, Embase, and Web of Science through September 2023 to identify studies evaluating the diagnostic precision of [18F]FDG PET/CT and [18F]FDG PET/MRI in detecting lymph node metastasis in nasopharyngeal carcinoma. Sensitivity and specificity were assessed through the DerSimonian-Laird method, incorporating the Freeman-Tukey transformation.

Results

The meta-analysis encompassed nine articles, involving a total of 916 patients. The overall sensitivity and specificity of [18F]FDG PET were 0.95 (95%CI: 0.88-1.00) and 0.95 (95%CI: 0.84-1.00). The overall sensitivity of [18F]FDG PET/CT was 0.94 (95%CI, 0.85-0.99), whereas [18F]FDG PET/MRI achieved a sensitivity of 1.00 (95%CI, 0.94-1.00). The findings reveal that [18F]FDG PET/CT demonstrates comparable sensitivity to [18F]FDG PET/MRI (p = 0.20). The overall specificity of [18F]FDG PET/CT was 0.94 (95%CI, 0.82-1.00), whereas [18F]FDG PET/MRI exhibited a specificity of 0.98 (95%CI, 0.93-1.00). Additionally, the results suggest that [18F]FDG PET/CT offers similar specificity to [18F]FDG PET/MRI (p = 0.11).

Conclusion

[18F]FDG PET demonstrates high sensitivity and specificity in identifying lymph node metastasis in nasopharyngeal carcinoma. Furthermore, [18F]FDG PET/CT exhibits comparable sensitivity and specificity to [18F]FDG PET/MRI.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=496006, PROSPERO (CRD42024496006).

Integrative approach of omics and imaging data to discover new insights for understanding brain diseases

Treatments that can completely resolve brain diseases have yet to be discovered. Omics is a novel technology that allows researchers to understand the molecular pathways underlying brain diseases. Multiple omics, including genomics, transcriptomics and proteomics, and brain imaging technologies, such as MRI, PET and EEG, have contributed to brain disease-related therapeutic target detection. However, new treatment discovery remains challenging. We focused on establishing brain multi-molecular maps using an integrative approach of omics and imaging to provide insights into brain disease diagnosis and treatment. This approach requires precise data collection using omics and imaging technologies, data processing and normalization. Incorporating a brain molecular map with the advanced technologies through artificial intelligence will help establish a system for brain disease diagnosis and treatment through regulation at the molecular level.

ACR Appropriateness Criteria® Staging and Post-Therapy Assessment of Head and Neck Cancer

Imaging of head and neck cancer at initial staging and as part of post-treatment surveillance is a key component of patient care as it guides treatment strategy and aids determination of prognosis. Head and neck cancer includes a heterogenous group of malignancies encompassing several anatomic sites and histologies, with squamous cell carcinoma the most common. Together this comprises the seventh most common cancer worldwide. At initial staging comprehensive imaging delineating the anatomic extent of the primary site, while also assessing the nodal involvement of the neck is necessary. The treatment of head and neck cancer often includes a combination of surgery, radiation, and chemotherapy. Post-treatment imaging is tailored for the evaluation of treatment response and early detection of local, locoregional, and distant recurrent tumor. Cross-sectional imaging with CT or MRI is recommended for the detailed anatomic delineation of the primary site. PET/CT provides complementary metabolic information and can map systemic involvement. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The Prognostic and Diagnostic Value of [18F]FDG PET/CT in Untreated Laryngeal Carcinoma

This study aims to determine the diagnostic accuracy of staging PET/CT and neck MRI in patients with laryngeal carcinoma and to assess the value of PET/CT in predicting progression-free survival (PFS) and overall survival (OS). Sixty-eight patients who had both modalities performed before treatment between 2014 and 2021 were included in this study. The sensitivity and specificity of PET/CT and MRI were evaluated. PET/CT had 93.8% sensitivity, 58.3% specificity, and 75% accuracy for nodal metastasis, whereas MRI had 68.8%, 61.1%, and 64.7% accuracy, respectively. At a median follow-up of 51 months, 23 patients had developed disease progression and 17 patients had died. Univariate-survival analysis revealed all utilized PET parameters as significant prognostic factors for OS and PFS (p-value < 0.03 each). In multivariate analysis, metabolic-tumor volume (MTV) and total lesion glycolysis (TLG) predicted better PFS (p-value < 0.05 each). In conclusion, PET/CT improves the accuracy of nodal staging in laryngeal carcinoma over neck MRI and adds to the prognostication of survival outcomes through the use of several PET metrics.

Changing Role of PET/CT in Cancer Care With a Focus on Radiotherapy

Positron emission tomography (PET) integrated with computed tomography (CT) has brought revolutionary changes in improving cancer care (CC) for patients. These include improved detection of previously unrecognizable disease, ability to identify oligometastatic status enabling more aggressive treatment strategies when the disease burden is lower, its use in better defining treatment targets in radiotherapy (RT), ability to monitor treatment responses early and thus improve the ability for early interventions of non-responding tumors, and as a prognosticating tool as well as outcome predicting tool. PET/CT has enabled the emergence of new concepts such as radiobiotherapy (RBT), radioimmunotherapy, theranostics, and pharmaco-radiotherapy. This is a rapidly evolving field, and this primer is to help summarize the current status and to give an impetus to developing new ideas, clinical trials, and CC outcome improvements.

Role of imaging test with radionuclides in the diagnosis and treatment of pheochromocytomas and paragangliomas

Radionuclide imaging tests with [¹²³I] Metaiodobenzylguanidine (MIBG), [¹⁸F] -fluorodeoxyglucose, [¹⁸F]-fluorodopa, or ⁶⁸Ga-DOTA(0)-Tyr(3)-octreotate are useful for the diagnosis, staging and follow-up of pheochromocytomas (PHEOs) and paragangliomas (PGLs) (PPGLs). In addition to their ability to detect and localize the disease, they allow a better molecular characterization of the tumours, which is useful for planning targeted therapy with iodine-131 (¹³¹I) -labelled MIBG or with peptide receptor radionuclide therapy (PRRT) with [¹⁷⁷Lu]-labelled DOTATATE or other related agents in patients with metastatic disease. In this review we detail the main characteristics of the radiopharmaceuticals used in the functional study of PPGLs and the role of nuclear medicine tests for initial evaluation, staging, selection of patients for targeted molecular therapy, and radiation therapy planning. It also offers a series of practical recommendations regarding the functional imaging according to the different clinical and genetic scenarios in which PPGLs occur, and on the indications and efficacy of therapy with [¹³¹I]-MIBG and ¹⁷⁷Lu-DOTATATE.

PET/CT and PET/MR Imaging of the Post-treatment Head and Neck: Traps and Tips

PET/computed tomography and PET/MR imaging are used to evaluate the post-treatment neck. Although 18F-FDG is helpful in the staging and treatment response assessment of head and neck cancer, recently developed PET radiotracers targeting specific surface markers are promising for applications of diagnostic problem solving and improved extent delineation. Diffusion-weighted MR imaging is helpful in the differential diagnosis of head and neck neoplasms, and improves the sensitivity and specificity for the detection of certain pathologies. Following standardized imaging parameters for PET/computed tomography and diffusion-weighted imaging in PET/MR imaging improves diagnostic accuracy and allows for future research data mining.

Clinical Applications of PET/MR Imaging

PET/MR imaging is in routine clinical use and is at least as effective as PET/CT for oncologic and neurologic studies with advantages with certain PET radiopharmaceuticals and applications. In addition, whole body PET/MR imaging substantially reduces radiation dosages compared with PET/CT which is particularly relevant to pediatric and young adult population. For cancer imaging, assessment of hepatic, pelvic, and soft-tissue malignancies may benefit from PET/MR imaging. For neurologic imaging, volumetric brain MR imaging can detect regional volume loss relevant to cognitive impairment and epilepsy. In addition, the single-bed position acquisition enables dynamic brain PET imaging without extending the total study length which has the potential to enhance the diagnostic information from PET.

[68Ga]-DOTATATE PET/MRI in the diagnosis and management of recurrent head and neck paraganglioma with spinal metastasis

Most head and neck paragangliomas (PGLs) are biochemically silent and often present with recurrence and metastases in association with hereditary syndromes. Whole-body functional imaging is increasingly used to detect tumor extent and guide treatment planning of PGLs. [68Ga]-DOTATATE, which targets somatostatin receptor 2 (SSTR2) overexpression, has emerged as a sensitive functional imaging modality in PGLs. We present a patient with metastatic glomus caroticum PGL in whom [68Ga]-DOTATATE PET/MRI provided a more accurate characterization of metastatic extent, as compared to gadolinium-enhanced MRI of the neck and whole body [18F]-FDG PET/CT. We then review the current literature and discuss the imaging implications of [68Ga]-DOTATATE PET/MRI in PGLs.

Post-treatment benign changes versus recurrence in non-lymphoid head and neck malignancies: can diffusion-weighted magnetic resonance imaging end up the diagnostic challenge?

Background

The aim of this prospective cohort study is to substantiate the added value of diffusion-weighted magnetic resonance imaging (DW-MRI) over conventional MRI assessment in the differentiation between locoregional recurrence/residual tumour and post-treatment benign changes in patients with non-lymphoid head and neck malignancies.

Thirty adult patients, each with a suspicious lesion on post-treatment imaging scans at the primary site of a previously treated non-lymphoid head and neck malignancy, were evaluated by MRI and diffusion-weighted imaging (DWI). The apparent diffusion coefficient (ADC) values of the lesions were calculated.

Results

Diffusion-weighted MRI yielded an accuracy of 90%, a sensitivity of 88.9%, a specificity of 91.7%, a positive predictive value of 94.1% and a negative predictive value of 84.6%. The mean ADC value of the lesions was lower in the “locoregional recurrence/residual tumour” group (1.08 × 10−3 mm2/s) compared to the “post-treatment benign changes” group (1.95 × 10−3 mm2/s); P < 0.001. An ADC cutoff value of 1.43 × 10−3 mm2/s achieved the same accuracy as the visual assessment by DW-MRI.

Conclusion

Incorporating the DWI sequence into the post-treatment imaging assessment protocol brings a substantial added value to conventional MRI assessment in patients with non-lymphoid head and neck malignancies. This valuable merit of DW-MRI can help avoid or, at least, largely minimize unnecessary or unfeasible tissue sampling. An ADC cutoff value of 1.43 × 10−3 mm2/s can also be utilized to aid in the assessment process.

PET/MRI of atherosclerosis

Myocardial infarction and stroke are the most prevalent global causes of death. Each year 15 million people worldwide die due to myocardial infarction or stroke. Rupture of a vulnerable atherosclerotic plaque is the main underlying cause of stroke and myocardial infarction. Key features of a vulnerable plaque are inflammation, a large lipid-rich necrotic core (LRNC) with a thin or ruptured overlying fibrous cap, and intraplaque hemorrhage (IPH). Noninvasive imaging of these features could have a role in risk stratification of myocardial infarction and stroke and can potentially be utilized for treatment guidance and monitoring. The recent development of hybrid PET/MRI combining the superior soft tissue contrast of MRI with the opportunity to visualize specific plaque features using various radioactive tracers, paves the way for comprehensive plaque imaging. In this review, the use of hybrid PET/MRI for atherosclerotic plaque imaging in carotid and coronary arteries is discussed. The pros and cons of different hybrid PET/MRI systems are reviewed. The challenges in the development of PET/MRI and potential solutions are described. An overview of PET and MRI acquisition techniques for imaging of atherosclerosis including motion correction is provided, followed by a summary of vessel wall imaging PET/MRI studies in patients with carotid and coronary artery disease. Finally, the future of imaging of atherosclerosis with PET/MRI is discussed.

Multimodal Imaging With Positron Emission Tomography/Computed Tomography and Magnetic Resonance Imaging to Detect Extracapsular Extension in Head and Neck Cancer

OBJECTIVES/HYPOTHESIS

To assess the ability of specific positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) features to detect extracapsular extension (ECE) in head and neck squamous cell carcinoma (HNSCC) patients.

STUDY DESIGN

Retrospective study in a tertiary certified university cancer institute.

METHODS

We performed a review of patients with advanced HNSCC at Bern University Hospital between 2014 and 2018. Patients with pretherapeutic PET/CT and/or MRI who underwent neck dissection were included, with 212 patients fulfilling inclusion criteria. Blinded evaluation of specific PET/CT and MRI features with respect to presence of ECE was performed. Histopathological examination of neck dissection specimens was used as the gold standard to determine ECE status.

RESULTS

Out of the 212 included patients, 184 had PET/CT, 186 MRI, and 158 both modalities. Overall clinical stage IV (odds ratio [OR]: 2.26, 95% confidence interval [CI]: 2.25-11.74), ill-defined margins in both PET/CT and MRI (OR: 3.48, 95% CI: 1.21-9.98 and OR: 2.14, 95% CI: 0.94-4.89, respectively), and a maximum standardized uptake value ≥ 10 (OR: 5.44, 95% CI: 1.21-9.98) were all significant independent predictors of ECE. When combined, these four features led to a cumulative score able to predict ECE status with an accuracy of 91.43%.

CONCLUSIONS

The current findings indicate specific features in PET/CT and MRI are potential predictors of ECE status and may help in pretherapeutic stratification in HNSCC.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E163-E169, 2021.