Cost-effectiveness of response evaluation after chemoradiation in patients with advanced oropharyngeal cancer using 18F-FDG-PET-CT and/or diffusion-weighted MRI.

BACKGROUND: Considerable variation exists in diagnostic tests used for local response evaluation after chemoradiation in patients with advanced oropharyngeal cancer. The yield of invasive examination under general anesthesia (EUA) with biopsies in all patients is low and it may induce substantial morbidity. We explored four response evaluation strategies to detect local residual disease in terms of diagnostic accuracy and cost-effectiveness. METHODS: We built a decision-analytic model using trial data of forty-six patients and scientific literature. We estimated for four strategies the proportion of correct diagnoses, costs concerning diagnostic instruments and the proportion of unnecessary EUA indications. Besides a reference strategy, i.e. EUA for all patients, we considered three imaging strategies consisting of 18FDG-PET-CT, diffusion-weighted MRI (DW-MRI), or both 18FDG-PET-CT and DW-MRI followed by EUA after a positive test. The impact of uncertainty was assessed in sensitivity analyses. RESULTS: The EUA strategy led to 96% correct diagnoses. Expected costs were €468 per patient whereas 89% of EUA indications were unnecessary. The DW-MRI strategy was the least costly strategy, but also led to the lowest proportion of correct diagnoses, i.e. 93%. The PET-CT strategy and combined imaging strategy were dominated by the EUA strategy due to respectively a smaller or equal proportion of correct diagnoses, at higher costs. However, the combination of PET-CT and DW-MRI had the highest sensitivity. All imaging strategies considerably reduced (unnecessary) EUA indications and its associated burden compared to the EUA strategy. CONCLUSIONS: Because the combined PET-CT and DW-MRI strategy costs only an additional €927 per patient, it is preferred over immediate EUA since it reaches the same diagnostic accuracy in detecting local residual disease while leading to substantially less unnecessary EUA indications. However, if healthcare resources are limited, DW-MRI is the strategy of choice because of lower costs while still providing a large reduction in unnecessary EUA indications.

Radiofrequency Ablation to Improve Survival After Conversion Chemotherapy for Colorectal Liver Metastases.

INTRODUCTION: Systemic chemotherapy is able to convert colorectal liver metastases (CRLM) that are initially unsuitable for local treatment into locally treatable disease. Surgical resection further improves survival in these patients. Our aim was to evaluate disease-free survival (DFS), overall survival, and morbidity for patients with CRLM treated with RFA following effective downstaging by chemotherapy, and to identify factors associated with recurrence and survival. MATERIALS AND METHODS: Included patients had liver-dominant CRLM initially unsuitable for local treatment but eligible for RFA or RFA with resection after downstaging by systemic chemotherapy. Chemotherapeutic regimens consisted predominantly of CapOx, with or without bevacizumab. Follow-up was conducted with PET-CT or thoraco-pelvic CT. RESULTS: Fifty-one patients had a total of 325 CRLM (median = 7). Following chemotherapy, 183 lesions were still visible on CT (median = 3). Twenty-six patients were treated with RFA combined with resection. During surgery, 309 CRLM were retrieved on intraoperative ultrasound (median = 5). Median survival was 49 months and was associated with extrahepatic disease at time of presentation and recurrences after treatment. Estimated cumulative survival at 1, 3 and 4 years was 90, 63 and 45 %, respectively. Median DFS was 6 months. Twelve patients remained free of recurrence after a mean follow-up of 32.6 months. CONCLUSION: RFA of CRLM after conversion chemotherapy provides potential local control and a good overall survival. To prevent undertreatment, the involvement of a multidisciplinary team in follow-up imaging and assessment of local treatment possibilities after palliative chemotherapy for liver-dominant CRLM should always be considered.

The correlation between clinical, nuclear and histologic findings in a patient with Von Recklinghausen's disease.

BACKGROUND: Malignant peripheral nerve sheath tumours (MPNST) are known to develop in patients with Neurofibromatosis type I (NF1) resulting in a decreased overall survival. The association between NF1 and the development of such MPNST has been investigated in detail. The biological behaviour however of multiple disseminated neurofibromas in patients with NF1 and the risk factors for malignant transformation remain unknown. Clinical signs are unreliable and additional imaging techniques are therefore required. Of such, positron emission tomography using [18F]-2-fluoro-2-deoxy-D-glucose (18FDG PET) is used to detect malignant changes in neurofibromas. CASE PRESENTATION: A case is presented of a patient suffering from NF1 with clinical signs of malignant change and accumulation of 18FDG in multiple neurofibromas. Histopathological examination of 20 lesions however, did not reveal any malignant features. There was no statistically significant relation between18FDG accumulation and malignant change, but rather with pain, size and growth. CONCLUSION: This case adds to the knowledge of the diverse biological behaviour of neurofibromas in patients with NF1.

Altered GABAA receptor density and unaltered blood-brain barrier [11C]flumazenil transport in drug-resistant epilepsy patients with mesial temporal sclerosis.

Studies in rodents suggest that flumazenil is a P-glycoprotein substrate at the blood-brain barrier. This study aimed to assess whether [11C]flumazenil is a P-glycoprotein substrate in humans and to what extent increased P-glycoprotein function in epilepsy may confound interpretation of clinical [11C]flumazenil studies used to assess gamma-aminobutyric acid A receptors. Nine drug-resistant patients with epilepsy and mesial temporal sclerosis were scanned twice using [11C]flumazenil before and after partial P-glycoprotein blockade with tariquidar. Volume of distribution, nondisplaceable binding potential, and the ratio of rate constants of [11C]flumazenil transport across the blood-brain barrier (K1/k2) were derived for whole brain and several regions. All parameters were compared between pre- and post-tariquidar scans. Regional results were compared between mesial temporal sclerosis and contralateral sides. Tariquidar significantly increased global K1/k2 (+23%) and volume of distribution (+10%), but not nondisplaceable binding potential. At the mesial temporal sclerosis side volume of distribution and nondisplaceable binding potential were lower in hippocampus (both ∼-19%) and amygdala (both ∼-16%), but K1/k2 did not differ, suggesting that only regional gamma-aminobutyric acid A receptor density is altered in epilepsy. In conclusion, although [11C]flumazenil appears to be a (weak) P-glycoprotein substrate in humans, this does not seem to affect its role as a tracer for assessing gamma-aminobutyric acid A receptor density.

18 F-FDG PET standard uptake values of the normal pons in children: establishing a reference value for diffuse intrinsic pontine glioma.

BACKGROUND: Positron emission tomography (PET) scanning with [18 F]fluorodeoxyglucose (18 F-FDG) is a useful diagnostic and prediction tool in brain tumors, but its value in childhood diffuse intrinsic pontine glioma (DIPG) is still unclear. For interpretation of 18 F-FDG PET results in DIPG, uptake values of the normal pons of children of increasing ages are mandatory. The aim of this study was to determine 18 F-FDG standard uptake value ratios (SUVr) of the normal pons and to compare these to those of DIPG. METHODS: We studied 36 subjects with a normal, non-affected pons (aged 5 to 23 years) and 6 patients with DIPG (aged 4 to 17 years) who underwent 18 F-FDG PET scanning. Magnetic resonance imaging (MRI) was co-registered to define the regions of interest. SUVr and SUVrmax for the pons/cerebellum (SUVrp/c) and the pons/occipital lobe (SUVrp/o) were calculated. Independent-samples t tests and Mann-Whitney U tests were used to compare the mean SUVr and Pearson's test for correlations. RESULTS: For the normal pons, mean SUVrp/c and SUVrp/o were 0.65 (±0.054) and 0.51 (±0.056), respectively. No significant correlations were found between the SUVr of the normal pons and sex, age, nor pontine volume. A modest but statistically significant correlation was found between SUVr and post-injection time acquisition timing. For DIPG, mean SUVrp/c and SUVrp/o were 0.74 (±0.20) and 0.65 (±0.30), respectively, while mean SUVrp(max)/c and SUVrp(max)/o were 1.95 (±0.48) and 1.81 (±0.20), respectively. CONCLUSION: The SUVr of the unaffected pons are strikingly constant between children, irrespective of sex and age, and can therefore be well used as a reference value for 18 F-FDG PET studies in DIPG.

Assessment of tumour size in PET/CT lung cancer studies: PET- and CT-based methods compared to pathology.

BACKGROUND: Positron emission tomography (PET) may be useful for defining the gross tumour volume for radiation treatment planning and for response monitoring of non-small cell lung cancer (NSCLC) patients. The purpose of this study was to compare tumour sizes obtained from CT- and various more commonly available PET-based tumour delineation methods to pathology findings. METHODS: Retrospective non-respiratory gated whole body [18F]-fluoro-2-deoxy-D-glucose PET/CT studies from 19 NSCLC patients were used. Several (semi-)automatic PET-based tumour delineation methods and manual CT-based delineation were used to assess the maximum tumour diameter. RESULTS: 50%, adaptive 41% threshold-based and contrast-oriented delineation methods showed good agreement with pathology after removing two outliers (R2=0.82). An absolute SUV threshold of 2.5 also showed a good agreement with pathology after the removal of 5 outliers (R2: 0.79), but showed a significant overestimation in the maximum diameter (19.8 mm, p<0.05). Adaptive 50%, relative threshold level and gradient-based methods did not show any outliers, provided only small, non-significant differences in maximum tumour diameter (<4.7 mm, p>0.10), and showed fair correlation (R2>0.62) with pathology. Although adaptive 70% threshold-based methods showed underestimation compared to pathology (36%), it provided the best precision (SD: 14%) together with good correlation (R2=0.81). Good correlation between CT delineation and pathology was observed (R2=0.77). However, CT delineation showed a significant overestimation compared with pathology (3.8 mm, p<0.05). CONCLUSIONS: PET-based tumour delineation methods provided tumour sizes in agreement with pathology and may therefore be useful to define the (metabolically most) active part of the tumour for radiotherapy and response monitoring purposes.

Patients' perception of diagnostic tests in the preoperative assessment of esophageal cancer.

OBJECTIVE: Defining an optimal staging strategy requires an evaluation of the effectiveness and costs of diagnostic tests and may include the burden of these tests for patients. This study evaluated the burden of cervical ultrasonography (US), endoscopic ultrasonography (EUS), computed tomography (CT) and positron emission tomography (PET) in patients with esophageal carcinoma (EC). METHODS: Consenting consecutive patients underwent a standard preoperative work-up. Burden of testing was evaluated with a self-report questionnaire addressing anxiety, embarrassment, and discomfort, each measured on a 1(none) to 5 (extreme) point-scale. An overall burden score was calculated by summing the three item scores. In addition, patients were asked to rank the four tests from least to most inconvenient. Statistical analysis was performed with nonparametric tests. RESULTS: 82 patients (67 , 15 ; mean age 64.3 yrs) participated. For most tests and most dimensions of burden, the large majority of subjects was in categories 1 and 2.With respect to anxiety, the rank order (from highest burden to lowest burden) was EUS, US, PET, and CT (average scores 1.7, 1.5, 1.4, and 1.2, respectively). For embarrassment, the rank order was EUS, PET, US, and CT (1.9, 1.5, 1.4, and 1.3 respectively). For discomfort, the rank order was EUS, PET, US and CT (2.0, 1.6, 1.4, and 1.2, respectively). And for total burden, the rank order was EUS, PET, US and CT (5.6, 4.6, 4.2, and 3.7). PET was ranked as least inconvenient by 35% of patients and as most inconvenient by 16% compared with the other tests. CONCLUSION: Significant but small differences were observed in patient burden for imaging tests to evaluate EC. The perceived burden of PET was lower than that of EUS, but higher than the burden of CT. However absolute values were low for all tests and therefore patient burden will not be a key feature for the construction of an optimal staging algorithm for EC.