The value of 18F-fluorodeoxyglucose positron emission tomography for prediction of treatment response in gastrointestinal stromal tumors: a systematic review and metaanalysis

Background: Early detection of response to treatment is critically important in gastrointestinal stromal tumors (GIST). Therefore, the present systematic review and meta-analysis assessed the value of 18f-fluorodeoxyglucose positron emission tomography (18FDG– PET) on prediction of therapeutic response of GIST patients to systemic treatments. Methods: The literature search was conducted using PubMed, SCOPUS, Cochrane, and Google Scholar databases, and review article references. Eligible articles were defined as studies included confirmed GIST patients who underwent 18FDG–PET as well as assessing the screening role of it. Results: Finally, 21 relevant articles were included. The analysis showed the pooled sensitivity and specificity of 18FDG–PET in evaluation of response to treatment of GIST patient were 0.90 (95% CI: 0.85–0.94; I 2 = 52.59, P = 0.001) and 0.62 (95% CI: 0.49–0.75; I 2 = 69.7, P = 0.001), respectively. In addition, the pooled prognostic odds ratio of 18FDG–PET for was 14.99 (95% CI, 6.42–34.99; I 2 = 100.0, P < 0.001). The Meta regression showed that sensitivity of 18FDG-PET was higher if the sample size of study was equal or more than 30 cases (sensitivity = 0.93; 95% CI: 0.89–0.97), when using PET/CT (sensitivity = 0.92; 95% CI: 0.89–0.97), and self-design criteria (sensitivity = 0.93; 95% CI: 0.87–1.0). Conclusion: The present meta-analysis showed 18FDG–PET has a significant value in predicting treatment response in GIST patients

The Value of Technetium-99m Labeled Alpha-Melanocyte- Stimulating Hormone (99mTc-α-MSH) in Diagnosis of Primary and Metastatic Lesions of Malignant Melanoma

Objective(s): Malignant melanoma is the most lethal type of skincancers with unfavorable prognosis. Alpha-MSH peptide analogues havea high affinity for melanocortine-1 (MC1) receptors on melanocytes overexpressing in malignant melanoma cells. Pre-clinical studies have shownpromising results for radiolabeled MSH imaging in this malignancy. Thepurpose of this study is to assess the diagnostic value of 99mTc-α-MSHimaging in malignant melanoma.Methods: Twenty-one patients (13 men) with pathologically confirmedmalignant melanoma with or without metastatic distribution wereincluded in this study. 740-1110 MBq 99mTc-α-MSH was injected and wholebody scans were performed 20, 120 and 240 minutes post injection andwere assessed both qualitatively and semi-quantitatively using target (T)to background (BG) ratio.Results: The T/BG ratio for the primary tumor bed was 2.51±2.26,2.56±2.48 and 1.92±1.79 minutes in the whole body scans 20, 120 and 240minutes post injection, respectively. The sensitivity, specificity, negativeand positive predictive values were 75%, 80%, 50% and 92% for primarylesion and 25%, 100%, 68% and 100% for distant metastasis, respectively.Conclusion: 99mTc-α-MSH is a newly introduced agent for diagnosisof tumoral lesions in malignant melanoma. Our study showed a highsensitivity with this modality in primary lesions as well as lymph nodeinvolvements. However the detection rate was not high in distantmetastasis. The preliminary results are promising especially as a newcomplementary imaging method in management of malignant melanoma