R. Abgral

Does 18F-FDG PET/CT Improve the Detection of Posttreatment Recurrence of Head and Neck Squamous Cell Carcinoma in Patients Negative for Disease on Clinical Follow-up?

Posttreatment surveillance for the recurrence of head and neck squamous cell carcinoma (HNSCC) is a diagnostic challenge. Tissue distortion from radiation and surgery can obscure early detection of recurrence by conventional follow-up approaches such as physical examination, CT, and MRI. Several studies have shown that 18F-FDG PET may be an effective technique for the detection of persistent, recurrent, and distant metastatic HNSCC after treatment. The aim of this prospective study was to determine the benefits of hybrid 18F-FDG PET/CT in detecting a subclinical locoregional recurrence of HNSCC and distant metastases. The study patients were considered cured of HNSCC on the basis of 12 mo of negative findings on conventional follow-up. We also assessed the diagnostic accuracy of 18F-FDG PET/CT in these patients. Methods: Ninety-one patients cured of HNSCC without any clinical evidence of recurrence were included. Whole-body 18F-FDG PET/CT examination was performed 11.6 ± 4.4 mo after the end of the treatment. The gold standard was histopathology or 6 mo of imaging follow-up. Results: The whole-body 18F-FDG PET/CT examinations had negative results in 52 patients and positive results in 39. Nine of these patients who exhibited abnormal 18F-FDG uptake in the head and neck area did not have recurrent HNSCC (false-positive). Thirty had proven recurrence. The sensitivity and specificity of 18F-FDG PET/CT in this study for the diagnosis of HNSCC recurrence were 100% (30/30) and 85% (52/61), respectively. The positive predictive value was 77% (30/39). The negative predictive value was 100% (52/52). The overall accuracy was 90% (82/91). Conclusion: The results of our study confirm the high effectiveness of 18F-FDG PET/CT in the assessment of HNSCC recurrence and suggest that 18F-FDG PET/CT is more accurate than conventional follow-up physical examination alone in the assessment of recurrence after previous curative treatment for HNSCC and could be proposed systematically at 12 mo of the usual follow-up.

Does 18fluoro‐fluorodeoxyglucose positron emission tomography improve recurrence detection in patients treated for head and neck squamous cell carcinoma with negative clinical follow‐up?

The aim of this study was to determine the benefits of 18fluoro‐fluorodeoxyglucose positron emission tomography (18F‐FDG PET) in the detection of head and neck squamous cell carcinoma (HNSCC) recurrence in patients with negative clinical follow‐up.

Prognostic value of dual-time-point 18F-FDG PET-CT imaging in patients with head and neck squamous cell carcinoma.

ObjectiveThe objective of this study was to investigate the independent prognostic value of dual-time-point 18F-fluorodeoxyglucose (18F-FDG) PET-CT imaging in patients with head and neck squamous cell carcinoma (HNSCC). MethodsPatients referred to our department to undergo 18F-FDG PET-CT for staging of HNSCC were prospectively included. Each patient was scanned using a Philips Gemini PET-CT system 1 h (early acquisition) and 2 h (delayed acquisition) after injection. An intratumoral retention index (RI) of 18F-FDG was measured for each examination by the dual-time-point method. Event-free survival (EFS) and overall survival (OS) were determined by the Kaplan–Meier method and compared with the conventional maximum standardized uptake value (SUVmax) at 60 min, SUVmax at 120 min, and RI in univariate and multivariate analyses including the usual prognostic factors such as age, sex, primary site, SCC histologic grade, and American Joint Committee on Cancer stage (I, II, III, and IV). ResultsSixty-six consecutive patients (60 men and six women; mean age=61±9 years) were included in the study. In univariate analysis, besides age and stage, RI was predictive of EFS (P=0.01) but not of OS (P=0.1), whereas SUVmax at 60 min was not predictive of EFS (P=0.18) or OS (P=0.08) and SUVmax at 120 min was predictive of OS (P=0.02) but not of EFS (P=0.05). In multivariate analysis, RI persisted as an independent predictive factor for EFS (P=0.02) but not SUVmax at 120 min for OS (P=0.12). ConclusionOur results suggest an additional prognostic interest of RI measured by dual-time-point 18F-FDG PET-CT, independent of usual prognostic factors, in patients with HNSCC.

V/Q SPECT Interpretation for Pulmonary Embolism Diagnosis: Which Criteria to Use?

Ventilation–perfusion (V/Q) SPECT has been reported to improve the diagnostic performance of V/Q imaging for the diagnosis of pulmonary embolism (PE). However, only sparse data based on an objective reference test are available, and the criteria used for interpretation have varied widely. Therefore, the aim of our study was to assess the performance of V/Q SPECT using various criteria for interpretation, in comparison with a validated independent diagnostic strategy. Methods: The SPECT study included patients for whom V/Q SPECT data were compared with the results of an independent and validated diagnostic algorithm for PE. V/Q SPECT scans were performed after intravenous injection of 99mTc-macroaggregated albumin and simultaneous ventilation with 81mKr gas. Interpretation was performed independently by 2 nuclear medicine physicians who were not aware of the clinical history, diagnostic strategy conclusion, or patient’s outcome. Sensitivity, specificity, and likelihood ratios were evaluated for various combinations of mismatched defect numbers and sizes (segmental or subsegmental). Generation of receiver-operating-characteristic curves was based on the number of mismatch defects and the number of subsegmental mismatch defects or equivalent. Results: Of the 249 patients who were analyzed, the diagnosis of PE was confirmed in 49 and ruled out in 200 according to the previously validated independent strategy. Of all the tested criteria, the best performance was achieved using a diagnostic cutoff of at least 1 segmental or 2 subsegmental mismatches, with sensitivity and specificity of 0.92 (95% confidence interval, 0.84–1) and 0.91 (95% confidence interval, 0.87–0.95), respectively. With a negative V/Q SPECT result, the posttest probability of PE was 0.010, 0.037, and 0.119 for a low, intermediate, and high clinical probability. With a positive V/Q SPECT result, the posttest probability of PE was 0.531, 0.814, and 0.939 for a low, intermediate, and high probability. Conclusion: For V/Q SPECT interpretation, a diagnostic cutoff of 1 segmental or 2 subsegmental mismatches seems best for confirming or excluding acute PE.

Prognostic value of fluorine-18 fluorodeoxyglucose positron-emission tomography imaging in patients with head and neck squamous cell carcinoma

High tumor uptake of fluorodeoxyglucose (FDG) is associated with an unfavorable outcome in patients with cancer. We evaluated FDG uptake as a prognostic factor in patients with head and neck squamous cell carcinoma.

Performance of 18F fluoro-2-désoxy-D-glucose positron emission tomography/computed tomography for the diagnosis of venous thromboembolism

INTRODUCTION Thrombosis and inflammation are intimately linked. Inflammatory component of venous thromboembolism (VTE) may allow the use of FDG positron emission tomography / computed tomography (FDG PET/CT) in the detection of thrombotic process. Published studies remain limited and contradictory. We aimed at evaluating the performance of FDG PET/CT in the detection of VTE in a population of patients enrolled in a prospective study evaluating FDG PET/CT for cancer screening in etiological assessment of idiopathic VTE. MATERIALS AND METHODS The first consecutive 100 patients who underwent FDG PET/CT were included. Visual and quantitative analyses of vascular axes was performed and compared with lower limb veins compression ultrasonography, lung scintigraphy and/or computed tomography pulmonary angiography. RESULTS Out of the 100 patients, 63 presented lobar pulmonary embolism for a total of 217 embolic sites and 62 had a deep vein thrombosis for a total of 143 thrombotic sites. Regarding pulmonary embolism, sensitivity and specificity of FDG PET/CT were 3% (95%CI: 1-6%) and 99% (95%CI: 98-100%). SUV max ratio between pulmonary embolism location and non-pathological contralateral vessel was 1.04±0.18 (p=0.7). Regarding deep vein thrombosis, sensitivity and specificity were 31% (95%CI: 24-39%) and 88% (95%CI: 81-92%). The metabolic activity was significantly higher than in contralateral vessels (p<0.001), with a SUV max ratio of 1.25±0.53, but without any significant SUVmax threshold applicable in routine practice for deep vein thrombosis diagnosis. CONCLUSIONS FDG PET/CT is not accurate enough for the diagnosis of VTE.

Prognostic evaluation of percentage variation of metabolic tumor burden calculated by dual‐phase 18FDG PET‐CT imaging in patients with head and neck cancer

The purpose of this study was to investigate the prognostic value of percentage variation of metabolic tumor burden in patients with head and neck squamous cell carcinoma (HNSCC).

Additional value of combining low-dose computed tomography to V/Q SPECT on a hybrid SPECT-CT camera for pulmonary embolism diagnosis.

ObjectivesThe aim of the study was to assess the potential interest of combining a low-dose computed tomography (ldCT) to ventilation/perfusion (V/Q) single-photon emission computed tomography (SPECT) for the diagnosis of pulmonary embolism (PE). We addressed three main questions: Could ldCT be used in substitution to ventilation SPECT? Could ldCT improve the diagnostic performance of V/Q SPECT? Could ldCT provide alternative diagnoses to PE? MethodsA total of 393 patients previously analysed in a management outcome study that aimed at assessing the safety of V/Q SPECT for PE diagnosis were assessed. All patients underwent an ldCT under the same SPECT-computed tomography camera, which was not used at the time of initial interpretation. Three retrospective analyses were performed: Q SPECT combined with ldCT, V/Q SPECT combined with ldCT and ldCT only. ResultsOn the basis of initial V/Q SPECT interpretation, 110 (28%) patients were positive and 283 (72%) were negative for PE.With Q SPECT-ldCT, 139 (35%) patients were positive and 254 (65%) were negative, with 55 (19%) discrepancies when compared with V/Q SPECT. Of the 283 patients with negative V/Q SPECT, 42 were positive with V/Q SPECT-ldCT, and among the 110 patients with positive V/Q SPECT 13 were negative with V/Q SPECT-ldCT. On using V/Q SPECT-ldCT, 97 (25%) patients were positive and 296 (75%) were negative, with 13 (3%) discrepancies when compared with V/Q SPECT (all had had a positive V/Q SPECT but a negative V/Q SPECT-ldCT). Finally, 67 (24%) ldCT scans showed a potential alternative diagnosis to PE. ConclusionFor PE diagnosis with lung SPECT, the use of ldCT in substitution to ventilation SPECT is associated with a high risk of overdiagnosis. The diagnostic value of ldCT in addition to V/Q SPECT remains unclear. Further studies are needed to determine its potential role in PE diagnosis.

Diagnosis of pulmonary embolism: planar images generated from V/Q SPECT are not a reliable substitute for traditional planar V/Q scan.

ObjectivesThe use of summed planar images generated from single-photon emission computed tomography (SPECT) ventilation/perfusion (V/Q) scintigraphy has been proposed as a substitute for planar V/Q scans in order to use the revised PIOPED interpretation criteria when only SPECT acquisition is performed in patients with suspected pulmonary embolism. The aim was to evaluate the accuracy of angular summed planar scans in comparison with true planar images. MethodsPatients included in the ‘SPECT study’ assessing the diagnostic performance of V/Q SPECT were analysed. Angular summed planar images were generated from SPECT acquisition data and compared with true planar scans. ResultsAngular summed planar images were successfully generated for 246 patients. Regarding interobserver variability, the interpretation result was different for 15 (6%) summed planar scans with an excellent degree of agreement (&kgr;=0.92; 95% confidence interval 0.88–0.96). With regard to intermodality interpretation variability between conventional planar and angular summed images, the result was different for 63 (26%) of 246 patients with an intermodality degree of agreement of &kgr;=0.66 (95% confidence interval 0.58–0.73). ConclusionPlanar images generated from SPECT V/Q scintigraphy are not a reliable substitute for true planar V/Q images.

An atypical sarcoidosis involvement in FDG PET/CT: A case report

Rationale:Sarcoidosis is an idiopathic systemic inflammatory granulomatous disorder comprised of epithelioid and multinucleated giant cells with little necrosis which involve various organs. Laryngeal involvement is extremely rare, with a prevalence of about 0.5 to 1%. Diagnoses:Here we present a case of laryngeal involvement of sarcoidosis demonstrated on 18F-Fluorodesoxyglucose Positron-Emission Tomography/Computed Tomography (FDG PET/CT). Patient concerns:A 63 year-old man suffering from dysphonia was referred to our department for characterization of laryngeal lesion suspicious for cancer with non-informative biopsy, the sample was not sufficient for diagnosis. Interventions:FDG PET/CT showed a pathological uptake on the right vocal cord, but also highlighted a bilateral uptake in intrathoracic hilar lymphadenopathy areas, typically found in several inflammatory diseases. Outcomes:New laryngeal targeted biopsies revealed non-caseating epithelioid granulomas suggesting sarcoidosis involvement. After 6 months of systemic steroid treatment, FDG PET/CT showed a significant decrease of the laryngeal uptake. Lessons:This case shows the usefulness of FDG PET/CT to accurately assess inflammatory activity in rare extra-pulmonary sarcoidosis involvement. Moreover, this case emphasizes that FDG PET/CT is an interesting tool for assessing therapeutic efficacy of inflammatory diseases such as sarcoidosis.