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Background: Despite advances in treatment, residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal squamous cell carcinoma (SCC) remain a challenge in clinical management and require accurate and timely detection for optimal salvage therapy. This study aimed to compare the diagnostic value of Fluorine 18 ( 18 F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) in detecting residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal SCC., Methods: A prospective study was conducted on 30 patients who presented with new symptoms after definitive (chemo) radiotherapy for laryngeal (n = 21) and hypopharyngeal (n = 9) carcinoma. Both 18 F-FDG PET/CT and DW-MRI were performed and histopathologic analysis served as the standard of reference., Results: Histopathology showed 20 patients as positive and 10 as negative for tumors. 18 F-FDG PET/CT detected all tumors correctly but was falsely positive in one case. DW-MRI detected tumors in 18 out of 20 positive patients and correctly excluded tumors in all negative patients. The sensitivity and specificity of 18 F-FDG PET/CT were 100% and 90%, respectively, while the values for DW-MRI were 90% and 100%, respectively., Conclusions: The study concludes that 18 F-FDG PET/CT is slightly superior to DW-MRI in detecting residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal SCC. The combined use of 18 F-FDG PET/CT and DW-MRI can potentially improve specificity in therapy response evaluation., (© 2024 The Authors. Head & Neck published by Wiley Periodicals LLC.)

Purpose: Apparent diffusion coefficients (ADCs) derived from diffusion-weighted magnetic resonance imaging (DW-MRI) and metabolic parameters derived from 18 F-FDG positron emission tomography (PET) are promising prognostic indicators for head and neck squamous cell carcinoma (SCC). However, the relationship between them remains unclear. This study aimed to investigate the relationship between ADCs and metabolic parameters in hypopharyngeal SCC (HSCC) using integrated PET/MRI., Materials and Methods: Twenty-seven patients with biopsy-proven HSCC underwent integrated 18 F-FDG neck PET/MRI. ADCs of HSCC, including the mean and minimum ADC values (ADC mean and ADC min ), were measured manually on ADC maps. Metabolic parameters of HSCC, including maximum and mean standardized uptake values (SUV max and SUV mean ), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were calculated automatically on PET images. Spearman correlation coefficients were used to assess the relationships between ADCs and metabolic parameters in HSCC tumors as well as in tumor groups with different histological grading, clinical staging, and anatomical subsites. P values < 0.05 were considered statistically significant., Results: No significant correlation was observed between ADCs and 18 F-FDG PET metabolic parameters in the entire cohort, except for a significant inverse correlation between ADC mean and MTV (r = -0.556, P = 0.003). Furthermore, a significant inverse correlation was observed between ADC mean and MTV of HSCC in the moderately to well differentiated group (r ADCmean/MTV = -0.692, P = 0.006), stage III group (r ADCmean/MTV = -0.758, P = 0.003), and pyriform sinus group (r ADCmean/MTV = -0.665, P = 0.007), whereas no significant correlation was observed in the poorly differentiated group, stage IV group, or non-pyriform sinus group., Conclusions: Inverse correlation between ADC mean and MTV in the HSCC population was observed and the correlativity depended on histological grading, clinical staging, and anatomical subsites of HSCC., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Recurrent laryngeal/hypopharyngeal squamous cell carcinoma (LHSCC) is commonly associated with poor survival outcomes. We evaluated the prognostic role of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) parameters quantitatively measured in patients who underwent salvage treatments for recurrent LHSCC., Methods: This study involved 100 consecutive LHSCC patients who underwent 18 F-FDG PET/CT for recurrent staging and subsequent salvage treatments. Maximum standardized uptake value (SUV max ), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured using 18 F-FDG PET/CT. Cox proportional hazards regression analyses were used to assess the associations between quantitative 18 F-FDG PET/CT parameters and other clinicopathological factors with progression-free survival (PFS) and overall survival (OS)., Results: Two-year postsalvage PFS and OS rates were 67.9% and 74.3%, respectively. All 18 F-FDG PET parameters of SUV max , MTV, and TLG were significantly associated with poor PFS and OS outcomes after salvage treatment (all P < 0.05). Multivariate analyses revealed that recurrence site, MTV (>6.5 mL), and TLG (>17.1 g) were independent variables predictive of PFS. Karnofsky score, SUV max (>4.0), and TLG (>17.1 g) were the independent prognostic factors for OS., Conclusions: 18 F-FDG PET/CT can be useful in predicting postsalvage recurrence and survival in patients with recurrent LHSCC., (© 2018 Wiley Periodicals, Inc.)

Background and Purpose: The goal of this study was to improve target definition by deriving modality-specific margins for clinical target volumes (CTV) for laryngeal and hypopharyngeal cancer on CT, MRI and 18-FDG-PET., Material and Methods: Twenty-five patients with T3/T4 laryngeal/hypopharyngeal cancer underwent CT, MRI and 18-FDG-PET scans before laryngectomy. HE-sections were obtained from the surgical specimen and tumor was delineated (tumor HE ). The GTVs on CT and MRI were delineated in consensus. PET-based GTVs were automatically segmented. The three-dimensionally reconstructed specimen was registered to the various images. Modality-specific CTV margins were derived and added to the GTVs to achieve adequate tumor coverage. The resulting CTVs were compared with each other, to tumor HE , and to CTV CT10 constructed on CT with the clinical margin of 10mm., Results: CTV margins of 4.3mm (CT), 6.1mm (MRI) and 5.2mm (PET) were needed to achieve adequate tumor coverage. The median volumes of the resulting modality-specific CTVs were 44ml (CT), 48ml (MRI) and 39ml (PET), while the CTV 10mm was 80ml., Conclusion: For laryngohypopharyngeal tumors, 45-52% target volume reduction compared with CTV 10mm is achievable when modality-specific CTV margins are used. PET-based CTVs were significantly smaller compared to CT- and MRI-based CTVs., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

This study evaluated the prognostic significance of the maximum standardized uptake value of the primary site (pSUVmax) in 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) scans of patients with oropharyngeal or hypopharyngeal cancer who were treated using definitive radiotherapy. The study included 86 patients who were primarily treated with radiotherapy for oropharyngeal or hypopharyngeal cancer. Sixty-nine patients underwent concurrent chemotherapy. The associations between pre-treatment pSUVmax and treatment outcomes were evaluated. The most appropriate pSUVmax cut-off value for predicting disease-free survival (DFS) and local control (LC) was selected using receiver operating characteristic (ROC) curves. The median follow-up time for surviving patients was 60 months, while the median survival time in the entire patient cohort was 55 months. A pSUVmax cut-off value of 9.0 showed the best discriminative performance. Five-year OS and DFS rates were 65.9% and 60.0%, respectively. In univariate analyses, pSUVmax ( p = 0.009), T-stage ( p = 0.001), N-stage ( p = 0.039), and clinical stage ( p = 0.017) were identified as significant prognostic predictors for DFS. The multivariate analysis did not identify any statistically significant factors, but the association between pSUVmax and DFS was borderline significant ( p = 0.055). Interestingly, pSUVmax was predictive of local controllability in T1-T2 disease ( p = 0.024), but there was no significant association for T3-T4 disease ( p = 0.735). In this study, pSUVmax was predictive of DFS and LC in patients with oropharyngeal or hypopharyngeal cancer that was treated with definitive radiotherapy. pSUVmax was strongly associated with LC in T1-T2 disease.

Purpose: To evaluate candidate fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging biomarkers for head-and-neck chemoradiotherapy outcomes in the cooperative group trial setting., Methods and Materials: Radiation Therapy Oncology Group (RTOG) protocol 0522 patients consenting to a secondary FDG-PET/CT substudy were serially imaged at baseline and 8 weeks after radiation. Maximum standardized uptake value (SUVmax), SUV peak (mean SUV within a 1-cm sphere centered on SUVmax), and metabolic tumor volume (MTV) using 40% of SUVmax as threshold were obtained from primary tumor and involved nodes., Results: Of 940 patients entered onto RTOG 0522, 74 were analyzable for this substudy. Neither high baseline SUVmax nor SUVpeak from primary or nodal disease were associated with poor treatment outcomes. However, primary tumor MTV above the cohort median was associated with worse local-regional control (hazard ratio 4.01, 95% confidence interval 1.28-12.52, P=.02) and progression-free survival (hazard ratio 2.34, 95% confidence interval 1.02-5.37, P=.05). Although MTV and T stage seemed to correlate (mean MTV 6.4, 13.2, and 26.8 for T2, T3, and T4 tumors, respectively), MTV remained a strong independent prognostic factor for progression-free survival in bivariate analysis that included T stage. Primary MTV remained prognostic in p16-associated oropharyngeal cancer cases, although sample size was limited., Conclusion: High baseline primary tumor MTV was associated with worse treatment outcomes in this limited patient subset of RTOG 0522. Additional confirmatory work will be required to validate primary tumor MTV as a prognostic imaging biomarker for patient stratification in future trials., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Purpose: We investigated whether SUV parameters, from PET, can provide prognostic information for patients with oropharyngeal or hypopharyngeal cancer., Patients and Methods: Forty-eight patients with oropharyngeal or hypopharyngeal cancer who underwent PET before treatment were enrolled. A volume of interest was placed on PET images covering the entire tumor volume and metastatic lymph nodes, and the SUVmax, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured., Results: With the use of Kaplan-Meier analysis, age, SUVmean, MTV, and TLG predicted decreased disease-free survival (DFS). However, SUVmax was not associated with DFS. In multivariate analysis, the variables were included in 3 separate models. An SUVmean2.5 was an independent prognostic factor for DFS. Other SUV parameters, such as MTV and TLG, were associated with trends toward a decreasing DFS., Conclusions: SUVmean of PET was an independent prognostic factor for DFS in patients with oropharyngeal and hypopharyngeal cancer.

Objectives: We investigated the relationship between overall survival of patients and pretreatment [(18)F]-2-fluorodeoxyglucose ((18)F-FDG) uptake, assessed by positron emission tomography combined with computed tomography (PET/CT) in hypopharyngeal squamous cell carcinoma., Methods: Thirty-one patients who were newly diagnosed as resectable hypopharyngeal squamous cell carcinoma underwent pretreatment (18)F-FDG-PET/CT. We used the maximum standardized uptake value (SUVmax) as (18)F-FDG uptake. Overall survival rate was calculated by the Kaplan-Meier method., Results: The median SUVmax was 11.53 (range 2.49-22.33). Patients with SUVmax ≥ 13 significantly exhibited shorter overall survival in univariate analysis (p < 0.01). Moreover, by Cox proportional hazards model of multivariate analysis, SUVmax ≥ 13 was a significant prognostic factor independent of clinical T and N classification, and treatment group (p < 0.02)., Conclusions: These results suggested that SUVmax obtained by pretreatment (18)F-FDG PET/CT assessment is an important prognostic factor in patients with hypopharyngeal squamous cell carcinoma.

The number of diagnostic positron emission tomography/computed tomography (PET/CT) procedures performed in the USA and worldwide is rapidly increasing. Although the benefits of these procedures are obvious, the increasing use of radiopharmaceuticals requires a better understanding of potential adverse affects and their proper management. We present herein the first report of an allergic reaction to fluorodeoxyglucose in the setting of repeated PET/CT scans for restaging purposes in a patient with pyriform sinus cancer.

Background: Metabolic tumor volume (MTV) of (18)F-FDG PET/CT is a volumetric measurement of tumor cells with increased 18F-FDG uptake. We evaluated the prognostic value of MTV in patients with locoregionally advanced laryngeal and hypopharyngeal cancer., Patients and Methods: We evaluated 81 patients with advanced-stage squamous cell carcinoma of the laryngohypopharynx who underwent 18F-FDG PET/CT between January 2004 and September 2009. Clinicopathologic factors and MTV were analyzed for their association with locoregional control (LRC) and overall survival (OS)., Results: The 3-year LRC and OS for all patients were 70.9 and 78.7%, respectively, with a median follow-up of 40.4 months (range 24.5-90.1). In univariate analyses, MTV, primary site, and primary treatment strategy were associated with both LRC and OS (P<0.05). On multivariate analysis, MTV was an independent prognostic factor for both LRC [P=0.018; HR=3.141, 95% confidence interval (CI)=1.175-8.399] and OS (P=0.008; HR=3.758, 95% CI=1.415-9.982). Primary site was also a significant prognostic factor for LRC (P=0.047)., Conclusion: Pretreatment MTV is an independent prognostic factor in patients with locoregionally advanced squamous cell carcinoma of the larynx and hypopharynx.

Background: Focal methods to determine the source of recurrence are presented, tested for reproducibility and compared to volumetric approaches with respect to the number of recurrences ascribed to the FDG-PET positive and high dose volumes., Material and Methods: Six patients treated for hypopharyngeal squamous cell carcinoma were extracted from archives. Inclusion criteria were: FDG-PET/CT for primary radiotherapy planning and clinical complete remission followed by loco-regional relapse. CT scan at the time of recurrence was also required. The recurrence volume was delineated in the follow-up scans by a radiologist. Putative points of origin (PO) of the recurrence were determined by two strategies 1) defined by an oncologist or 2) as the center-of-volume (COV) of the recurrence. The most likely recurrence point of origin on the treatment planning scan was also determined. All expert based points of origin were repeated to estimate reproducibility. The recurrence volume and PO were propagated to the treatment planning scan using a rigid transformation. Relations of the PO to target volumes, radiation doses and therapy-points-of-origin were quantified. For the volumetric methods, the overlap of the recurrence volume and target volumes was used to determine the source of the recurrence., Results: All recurrences were located in-field, but the volumetric approaches tended to designate fewer recurrences in the PET positive volume (25% for the 95% threshold, 95% confidence interval (CI):3-65%) than the observer-based methods (50% for the COV and both expert evaluations on the recurrence scan, 95% CI: 16-84%). The reproducibility of the expert POs is better on the recurrence scan than on the therapy scan., Conclusion: Volumetric approaches favor large target volumes as the source of the recurrence, thus underestimating the number of recurrences originating in the PET positive volume. Expert based and COV approaches on the recurrence scan are the most reproducible methods to determine the PO.

Purpose: Retropharyngeal lymph node (RPLN) metastasis is a poor prognosticator in oropharyngeal and hypopharyngeal cancers. The purpose of this study is to evaluate the impact of F-fluorodeoxyglucose positron emission tomography (F-FDG PET) on the diagnosis and predictor analysis of RPLN in these cancers., Methods: We enrolled patients with oropharyngeal and hypopharyngeal cancers before receiving definitive treatment. Staging was performed by F-FDG PET and conventional imaging modalities. Differences in RPLN metastasis detection rates were compared. Independent predictors of RPLN involvement were also assessed., Results: A total of 224 patients were investigated. RPLN involvement was identified in 17% of the study patients. In 18% of the 38 patients with RPLN involvement, RPLN metastases were identified by F-FDG PET only. Only 4% of the patients with oropharyngeal cancer and RPLN metastasis were not identified without the use of F-FDG PET, compared with 46% of patients with hypopharyngeal cancer. In multivariate analysis, posterior pharyngeal wall tumor (P=0.02) or the presence of ipsilateral level V lymph node metastasis (P=0.025) were independent predictors of RPLN involvement in hypopharyngeal cancer. In oropharyngeal cancer, no factors retained their independent significance., Conclusion: We concluded that F-FDG PET is helpful in detecting RPLN metastasis in hypopharyngeal cancer. The presence of ipsilateral level V lymph node metastasis or tumors originating from the posterior pharyngeal wall can predict RPLN involvement in hypopharyngeal cancer and might represent an indication for elective irradiation of this nodal basin. However, regional lymph node involvement is not an independent predictor in oropharyngeal cancer. The predictor for RPLN metastasis seems to change after the introduction of PET.

Purpose: To evaluate prognostic value of pretreatment and posttreatment 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) in advanced hypopharyngeal carcinoma treated by chemoradiotherapy., Procedures: Thirty-one patients underwent a baseline FDG-PET and then FDG-PET was repeated 7 weeks after chemoradiotherapy. Primary tumor uptake of FDG, measured as the maximal standardized uptake value (SUV(max)), was analyzed in relation to local control and survival., Results: Neither local control nor cause-specific survival were associated with pretreatment SUV(max). In contrast, patients with a high posttreatment SUV(max) had significantly poorer local control (P = 0.002), as well as poorer cause-specific survival (P = 0.0075), compared to those with a low posttreatment SUV(max). This prognostic significance of posttreatment SUV(max) remained when only a subset of patients showing local complete response to chemoradiotherapy was analyzed., Conclusions: Posttreatment FDG uptake represents an independent prognostic factor for hypopharyngeal carcinoma treated by chemoradiotherapy. Patients with a high posttreatment FDG uptake may benefit from adjuvant chemotherapy.

The recent progresses performed in imaging, computational and technological fields bring new opportunities to achieve high precision radiation dose delivery. However, IMRT requires a particular attention at the target delineation step to avoid inadequate dosage to TVs/OARs. In this context, the biological information provided by PET might advantageously complete CT-Scan to refine the target delineation in HNSCC and lung cancer. Integrating PET into the treatment planning however requires the use and validation of accurate and reproducible segmentation methods, which adequately integrate the PET image properties such as the blur effect and the high level of noise. In this context, we developed specific tools, i.e. edge-preserving filters for denoising and deconvolution algorithms for deblurring that allowed the detection of gradient intensity peaks. Our gradient-based method has been validated on phantom and patient materials, and proved to be more accurate than threshold-based approaches. With this tool in hand, we demonstrated that the use of FDG-PET resulted in smaller TVs than the CT-based TVs, on both pre- and per-treatment images, and significantly improved the dose distributions to the TVs/OARs. This opens avenues for dose escalation strategies that might potentially improve the tumor local control.

Aim: To examine the utility of 2'-[18F]-fluoro-2'-deoxy-D-glucose positron emission tomography (FDG-PET) for detecting multiple primary cancers (MPC) in patients with hypopharyngeal cancer (HPC)., Patients, Methods: Seventy patients with HPC underwent FDG-PET to determine the staging. Routine clinical examinations were carried out, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), and oesophagealgastroduodenoscopy (EGDS). The detection rate of synchronous and metachronous cancer was calculated based on FDG-PET alone or FDG-PET combined with clinical routine examination. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy were used to diagnose oesophageal cancer using FDG-PET., Results: Of the 70 patients, 12 (17.1%) had 15 synchronous tumours, and 2 of the 58 remaining patients (3.4%) had metachronous tumours. Oesophageal cancer was discovered most frequently: superficial type (n=6), advanced type (n=4). On a per-patient basis, 11 of 12 patients (91.6%) were diagnosed with synchronous tumours, and on a per-lesion basis, 12 of 15 lesions (80.0%) were detected by FDG-PET. The sensitivity, specificity, accuracy, PPV, and NPV of FDG-PET regarding oesophageal cancer were 70%, 100%, 95.7%, 100%, and 95.2% respectively. Three of the six superficial types were positive on FDG-PET. Both of the metachronous tumour lesions were detected by FDG-PET., Conclusion: FDG-PET is useful for estimating the MPC in HPC patients. Since 3 of 10 synchronous oesophageal cancer were missed with PET alone, a combination with EGDS should be considered to exclude synchronous oesophageal cancer.

Objective: Prospectively evaluate the impact of fluorodeoxyglucose-fluorine-18 positron emission tomography (FDG-PET) in the management of recurrence of advanced head and neck squamous cell carcinoma during the first year after treatment., Study Design: Seventy patients were followed-up every 6 to 8 weeks during the first year after initial combined curative therapy. FDG-PET, together with conventional imaging and endoscopy were performed systematically at 1 year (group A) or prompted earlier in case of clinically suspicious recurrence (group B). The referring physician evaluated the impact of FDG-PET on the patient's management. Another clinician checked the pertinence of decisions., Results: FDG-PET had a therapeutic impact in 8 of 43 group A patients and in 16 of 27 group B patients; the overall rate was 34%. This change was pertinent in 5 of 8 and 14 of 16 cases, respectively. Overall pertinence rate of decisions was 90% versus 70% without FDG-PET., Conclusions: FDG-PET had a significant overall therapeutic impact; the induced decisions were either pertinent or just led to "futile" noninvasive examinations. Systematic FDG-PET had a significantly lesser impact in comparison with FDG-PET motivated by clinical suspicion.

Background: High uptake of 2-[(18)F]-fluoro-2-deoxy-D-glucose (FDG) is associated with unfavorable results. Pretreatment FDG uptake was evaluated as a predictor of survival and guidance for primary surgery or radiotherapy (RT) in patients with squamous cell carcinoma (SCC) of the larynx and hypopharynx., Materials and Methods: Seventy-nine consecutive patients with newly diagnosed advanced resectable SCC of the larynx and hypopharynx underwent FDG positron emission tomography (PET) before surgical resection plus RT and chemotherapy (surgery group, n=40) or RT with chemotherapy and surgical salvage (RT group, n=39). Age, tumor stage, histological grade, treatment strategy, and standardized uptake value (SUV) were analyzed for association with local control and survival., Results: Overall local control and survival in the two groups did not differ (P>0.1). In univariate analysis, nodal positivity (P=0.014) and SUV>8.0 (P=0.007) were associated with poorer disease-free survival (DFS). In multivariate analysis, SUV remained an independent determinant of DFS (P=0.014). When patients with SUV>8.0 in the two treatment groups were analyzed separately, those in the surgery group tended to have a higher 3-year DFS than those in the RT group, despite no statistical significance (48% vs. 27%, P=0.085)., Conclusions: High FDG uptake is associated with poor survival in patients with advanced laryngopharyngeal SCC. Patients with high FDG uptake may be better treated by surgical resection followed by RT and chemotherapy.

Objective: To evaluate the function of fluorine-18-fluorodeoxyglucose (18F-FDG) in the diagnose of hypopharyngeal cancer., Method: Twenty patients with hypopharyngeal cancer were entered in the research. Every clinical information was collected carefully, including 18F-FDG, CT scanner and panendoscopy (pharyngo-laryngo-broncho-oesophagien), compared and analysed with each other., Result: The study showed 18 positive 18F-FDG reactions among these 20 patients, including 5 ectopia reactions. Compared with the clinical and pathology exam, we found that 18F-FDG exam had a good correspondance, with such good sensitivity and specificity., Conclusion: 18F-FDG reaction is useful in the diagnose of hypopharyngeal cancer, especially for the detection of the secondary secret cancer; also useful for the follow-up exam.

While fluorine-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is helpful in the pretherapeutic evaluation of head and neck cancer, it is only available in selected centres. Therefore, single-photon emission tomography (SPET) tracers would be desirable if they were to demonstrate tumour uptake reliably. This multitracer study was performed to evaluate the pretherapeutic uptake of the SPET tracers iodine-123 alpha-methyl-L-tyrosine (IMT) and technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) in primary carcinomas of the hypopharynx and larynx and to compare the results with those of FDG PET. We examined 22 fasted patients (20 male, 2 female, mean age 60.5+/-10.2 years) with histologically confirmed carcinoma of the hypopharynx (n=9) or larynx (n=13), within 1 week before therapy. In 20 patients a cervical PET scan was acquired after intravenous injection of 232+/-43 MBq 18F-FDG. Data analysis was semiquantitative, being based on standardised uptake values (SUVs) obtained at 60-90 min after injection. After injection of 570+/-44 MBq 99mTc-MIBI, cervical SPET scans (high-resolution collimator, 64x64 matrix, 64 steps, 40 s each) were obtained in 19 patients, 15 and 60 min after tracer injection. Finally, 15 min after injection of 327+/-93 MBq 123I-IMT (medium-energy collimator, 64x64 matrix, 64 steps, 40 s each) SPET scans were acquired in 15 patients. All images were analysed visually and by calculating the tumour to nuchal muscle ratio. Eighteen of 20 (90%) carcinomas showed an increased glucose metabolism, with a mean SUV of 8.7 and a mean carcinoma to muscle ratio of 7.3. The IMT uptake was increased in 13 of 15 (87%) patients, who had a mean carcinoma to muscle ratio of 2.9. Only 13 of 19 (68%) carcinomas revealed pathological MIBI uptake, with a mean tumour to muscle ratio of 2.2 and no significant difference between early and late MIBI SPET images (P=0.23). In conclusion, in the diagnosis of primary carcinomas of the hypopharynx and larynx, IMT SPET achieved a detection rate comparable to that of FDG PET. IMT SPET was clearly superior to MIBI SPET in this population. A further evaluation of the specificity of IMT in a larger number of patients appears justified.

Primary tumors of the larynx and hypopharynx are preferably treated with high-dose radiation therapy. In these patients, it may be difficult to distinguish recurrent disease from post-treatment reactions. The aim of the present study was to assess the value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in the detection of local relapses of laryngeal or hypopharyngeal carcinoma after radiotherapy using a dual-head PET camera. Forty-eight patients (43 male, 5 female; mean age +/-SD, 61+/-9.5 years) with suspected recurrent laryngeal or hypopharyngeal cancer were prospectively studied. The mean interval between initial treatment and suspicion of recurrent disease was 14.6 months (range: 3-100 months). FDG dual-head PET was followed by endoscopy with or without biopsy under general anaesthesia within a period of 2 months in all patients. The mean period of follow-up after FDG dual-head PET was 13.7 months. In 19 out of 31 patients with focally increased uptake, tumour recurrence (mean diameter: 2.4 cm; range 0.4-6.5 cm) was found at initial endoscopy. In five patients recurrence was found during follow-up with a mean interval of 6.6 months. Seven patients had a false-positive study due to benign lesions or swallowing artefacts. In none of the patients with a normal PET study was tumour recurrence found during follow-up. The sensitivity and specificity of FDG dual-head PET were 100% and 71%, respectively. It is concluded that FDG dual-head PET is highly sensitive for the detection of local recurrence of laryngeal and hypopharyngeal carcinoma after radiotherapy. Some lesions were detected with a mean interval of 6.6 months before histological confirmation. In patients suspected of having recurrent laryngeal or hypopharyngeal cancer in whom FDG-PET is negative, endoscopy may be omitted for at least 6 months and possibly for up to 1 year.