Detection of loco-regional recurrence in malignant head and neck tumors: a comparison of CT, MRI, and FDG PET-CT

Reconstructive flap surgery in head and neck cancer patients: an interdisciplinary view of the challenges encountered by radiation oncologists in postoperative radiotherapy

Background

Major advances have been made in reconstructive surgery in the last decades to reduce morbidity in head and neck cancer. Flaps are now present in 80% of patients with oral cavity cancer to cover anatomic, functional, and cosmetic needs. However, gaps in interdisciplinary innovation transfer from surgery to postoperative radiotherapy (poRT) remain challenging. We aimed to provide an interdisciplinary view of the challenges encountered by radiation oncologists in planning head and neck postoperative radiotherapy.

Methods

A systematic and critical review was conducted to address areas of optimization in surgery and radiology that may be relevant to poRT.

Results

Despite extensive surgical literature on flap techniques and salvage surgery, 13 retrospective series were identified, where flap outcomes were indirectly compared between surgery alone or poRT. These low-evidence studies suggest that radiotherapy accelerates flap atrophy, fibrosis, and osteoradionecrosis and deteriorates functional outcomes. Preliminary evidence suggests that tumor spread occurs at the flap-tissue junction rather than in the flaps. One prospective 15-patient study showed 31.3% vs. 39.2% flap volume reduction without or with poRT. In an international consensus, experts recognized the needs for optimized flap-sparing poRT against flap-related functional deterioration and bone damage. CT, MRI, and PET-CT modalities show potential for the delineation of the junction area between native tissues and flap for flap segmentation and to characterize flap-specific changes quantitatively and correlate them with patterns of relapse or complications.

Conclusion

Flap management in poRT is insufficiently documented, but poRT seems to damage flaps. Current gaps in knowledge underscore the need for prospective flap assessment and interdisciplinary trials investigating flap morbidity minimization by flap-sparing poRT planning.

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.

Systematic review and meta-analysis of the diagnostic effectiveness of positron emission tomography-computed tomography versus magnetic resonance imaging in the post-treatment surveillance of head and neck squamous cell carcinoma

OBJECTIVE

There is currently no consensus on the ideal protocol of imaging for post-treatment surveillance of head and neck squamous cell carcinoma. This study aimed to consolidate existing evidence on the diagnostic effectiveness of positron emission tomography-computed tomography versus magnetic resonance imaging.

METHOD

Systematic electronic searches were conducted using Medline, Embase and Cochrane Library (updated February 2021) to identify studies directly comparing positron emission tomography-computed tomography and magnetic resonance imaging scans for detecting locoregional recurrence or residual disease for post-treatment surveillance.

RESULTS

Searches identified 3164 unique records, with three studies included for meta-analysis, comprising 176 patients. The weighted pooled estimates of sensitivity and specificity for scans performed three to six months post-curative treatment were: positron emission tomography-computed tomography, 0.68 (95 per cent confidence interval, 0.49-0.84) and 0.89 (95 per cent confidence interval, 0.84-0.93); magnetic resonance imaging, 0.72 (95 per cent confidence interval, 0.54-0.88) and 0.85 (95 per cent confidence interval, 0.79-0.89), respectively.

CONCLUSION

Existing studies do not provide evidence for superiority of either positron emission tomography-computed tomography or magnetic resonance imaging in detecting locoregional recurrence or residual disease following curative treatment of head and neck squamous cell carcinoma.

Utility of diffusion MRI characteristics of cervical lymph nodes as disease classifier between patients with head and neck squamous cell carcinoma and healthy volunteers

Diffusion MRI characteristics assessed by apparent diffusion coefficient (ADC) histogram analysis in head and neck squamous cell carcinoma (HNSCC) have been reported as helpful in classifying tumours based on diffusion characteristics. There is little reported on HNSCC lymph nodes classification by diffusion characteristics. The aim of this study was to determine whether pretreatment nodal microstructural diffusion MRI characteristics can classify diseased nodes of patients with HNSCC from normal nodes of healthy volunteers. Seventy-nine patients with histologically confirmed HNSCC prior to chemoradiotherapy, and eight healthy volunteers, underwent diffusion-weighted (DW) MRI at a 1.5-T MR scanner. Two radiologists contoured lymph nodes on DW (b = 300 s/m² ) images. ADC, distributed diffusion coefficient (DDC) and alpha (α) values were calculated by monoexponential and stretched exponential models. Histogram analysis metrics of drawn volume were compared between patients and volunteers using a Mann-Whitney test. The classification performance of each metric between the normal and diseased nodes was determined by receiver operating characteristic (ROC) analysis. Intraclass correlation coefficients determined interobserver reproducibility of each metric based on differently drawn ROIs by two radiologists. Sixty cancerous and 40 normal nodes were analysed. ADC histogram analysis revealed significant differences between patients and volunteers (p ≤0.0001 to 0.0046), presenting ADC distributions that were more skewed (1.49 for patients, 1.03 for volunteers; p = 0.0114) and 'peaked' (6.82 for patients, 4.20 for volunteers; p = 0.0021) in patients. Maximum ADC values exhibited the highest area under the curve ([AUC] 0.892). Significant differences were revealed between patients and volunteers for DDC and α value histogram metrics (p ≤0.0001 to 0.0044); the highest AUC were exhibited by maximum DDC (0.772) and the 25th percentile α value (0.761). Interobserver repeatability was excellent for mean ADC (ICC = 0.88) and the 25th percentile α value (ICC = 0.78), but poor for all other metrics. These results suggest that pretreatment microstructural diffusion MRI characteristics in lymph nodes, assessed by ADC and α value histogram analysis, can identify nodal disease.

PET Imaging for Head and Neck Cancers

Head and neck cancers are commonly encountered cancers in clinical practice in the United States. Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET/CT has been clinically applied in staging, occult primary tumor detection, treatment planning, response assessment, follow-up, recurrent disease detection, and prognosis prediction in these patients. Alternative PET tracers remain investigational and can provide additional valuable information such as radioresistant tumor hypoxia. The recent introduction of ¹⁸F-FDG PET/MR imaging has provided the advantage of combining the superior soft tissue resolution of MR imaging with the functional information provided by ¹⁸F-FDG PET. This article is a concise review of recent advances in PET imaging in head and neck cancer.

Surveillance Imaging Following Head and Neck Cancer Treatment and Microvascular Reconstruction

OBJECTIVES/HYPOTHESIS

To assess the accuracy and utility of positron emission tomography/computed tomography (PET/CT) compared with magnetic resonance imaging (MRI) for detecting head and neck cancer (HNC) recurrence after microvascular reconstructive surgery.

STUDY DESIGN

Retrospective cohort study.

METHODS

Analysis of HNC patients who underwent microvascular reconstruction at a single, tertiary academic center following ablative surgery from 1998 to 2015. Forty-six patients aged 61.4 ± 15.8 years with both PET/CT and MRI examinations were identified. Two radiologists were blinded and interpreted each imaging study. Recurrence certainty scores were determined via continuous (0-100) and Likert ("Likely" to "Unlikely") scales, with larger values indicating a higher likelihood of recurrence. Pathologic confirmation of recurrence was confirmed in 23 patients (50%).

RESULTS

Among those with primary site recurrences, mean recurrence certainty was significantly higher with PET/CT versus MRI on the continuous scale (63.9 vs. 44.4, P = .006). A receiver operating characteristic analysis for predicting primary site recurrence demonstrated a significantly larger area under the curve of 0.79 for PET/CT compared to 0.64 for MRI (P = .044). Categorization of "Likely" primary site recurrence on PET/CT, versus MRI, had higher sensitivity (0.63 vs. 0.40), but lower specificity (0.90 vs. 1.0). MRI demonstrated higher sensitivity (1.0 vs. 0.78) at detecting regional site recurrences.

CONCLUSION

PET/CT demonstrates greater sensitivity than MRI as a surveillance tool for primary site recurrence following microvascular reconstruction where clinical evaluation is hindered by anatomical distortion. Therefore, PET/CT should be pursued as first-line imaging, with MRI utilized for confirmation of positive imaging findings at the primary site.

LEVEL OF EVIDENCE

2 Laryngoscope, 2021.

Can Radiographic Tumor Volume of Oral Squamous Cell Carcinoma Help Predict Clinical and Pathological Tumor Features?

PURPOSE

Radiographic tumor volume (RTV) of oral squamous cell carcinoma (SCC) is seldom measured in practice. Aims of the study are to estimate RTV of SCC and to investigate its relationship with clinical and pathological stage, tumor margin status, recurrence, and need for chemo/radiation.

METHODS

The Design is a retrospective cohort study. The predictor variable is SCC RTV. The primary outcome variables are clinical and pathological tumor size. The secondary outcomes are margin status and postoperative chemo/radiation. Tumor dimensions were measured on preoperative maxillofacial or neck computer tomography images with contrast. Information on patient and tumor characteristics was obtained. Pearson correlation, t test, ANOVA and log rank test were used for statistical analysis. The significance level was set at .05.

RESULTS

Thirty-Six subjects aged 36 to 86 were included in the study. Positive association was found between clinical T stage and RTV (P = .0003) and between pathologic T stage and RTV (P = .002). Mean value of RTV was significantly higher in group with positive margins (P = .0004). RTV was significantly higher in cancers requiring adjuvant chemo/radiation (P = .033). Mean RTV for patients with recurrence was 1.86 cm³ as compared to 1.29 cm³ for patients with no recurrence. Higher tumor volumes were more likely to be associated with recurrence.

CONCLUSIONS

RTV is a variable that is readily available to head and neck surgeons. RTV is associated with clinical and pathological tumor sizes, margin status, need for adjuvant chemo/radiation and tumor recurrence.

Predictive Value of Early Post-Treatment Diffusion-Weighted MRI for Recurrence or Tumor Progression of Head and Neck Squamous Cell Carcinoma Treated with Chemo-Radiotherapy

Aims: To investigate the predictive capacity of early post-treatment diffusion-weighted magnetic resonance imaging (MRI) for recurrence or tumor progression in patients with no tumor residue after chemo-radiotherapy (CRT) for head and neck squamous cell carcinoma, and, to assess the predictive capacity of pre-treatment diffusion-weighted MRI for persistent tumor residue post-CRT. Materials and Method: A single center cohort study was performed in one French hospital. All patients with squamous cell carcinoma receiving CRT (no surgical indication) were included. Two diffusion-weighted MRI were performed: one within 8 days before CRT and one 3 months after completing CRT with determination of median tumor apparent diffusion coefficient (ADC). Main outcome: The primary endpoint was progression-free survival. Results: 59 patients were included prior to CRT and 46 (78.0%) completed CRT. A post-CRT tumor residue was found in 19/46 (41.3%) patients. In univariate analysis, initial ADC was significantly lower in patients with residue post CRT (0.56 ± 0.11 versus 0.79 ± 0.13; p < 0.001). When initial ADC was dichotomized at the median, initial ADC lower than 0.7 was significantly more frequent in patients with residue post CRT (73.7% versus 11.1%, p < 0.0001). In multivariate analysis, only initial ADC lower than 0.7 was significantly associated with tumor residue (OR = 22.6; IC [4.9–103.6], p < 0.0001). Among 26 patients without tumor residue after CRT and followed up until 12 months, 6 (23.1%) presented recurrence or progression. Only univariate analysis was performed due to a small number of events. The only factor significantly associated with disease progression or early recurrence was the delta ADC (p = 0.0009). When ADC variation was dichotomized at the median, patients with ADC variation greater than 0.7 had time of disease-free survival significantly longer than patients with ADC variation lower than 0.7 (377.5 [286–402] days versus 253 [198–370], p < 0.0001). Conclusion and relevance: Diffusion-weighted MRI could be a technique that enables differentiation of patients with high potential for early recurrence for whom intensive post-CRT monitoring is mandatory. Prospective studies with more inclusions would be necessary to validate our results.