Year : 2011 | Volume
: 27 | Issue : 3 | Page : 428--429
Role of combined fluoro-deoxyglucose positron emission tomography with computed tomography for bladder tumor
Swarnendu Mandal, Manoj Yadav, Apul Goel
Department of Urology, C.S.M. Medical University (Upgraded King George's Medical College), Lucknow, Uttar Pradesh, India
Department of Urology, C.S.M. Medical University (Upgraded King George«SQ»s Medical College), Lucknow, Uttar Pradesh
|How to cite this article:|
Mandal S, Yadav M, Goel A. Role of combined fluoro-deoxyglucose positron emission tomography with computed tomography for bladder tumor.Indian J Urol 2011;27:428-429
|How to cite this URL:|
Mandal S, Yadav M, Goel A. Role of combined fluoro-deoxyglucose positron emission tomography with computed tomography for bladder tumor. Indian J Urol [serial online] 2011 [cited 2020 Jul 13 ];27:428-429
Available from: http://www.indianjurol.com/text.asp?2011/27/3/428/85459
The objective of this study was to investigate the role of fluoro-deoxyglucose positron emission tomography (FDG-PET) combined with computed tomography (CT) and forced diuresis, in the staging and follow-up of bladder carcinoma. CT scan was fused to increase the diagnostic accuracy of FDG-PET alone while forced diuresis with furosemide ensured that there was no hindrance due to the radiotracer to detect tumor in urinary bladder and pelvic lymph nodes. Seventy patients were prospectively enrolled. This included 44 patients with muscle-invasive urinary bladder cancer awaiting radical cystectomy, 19 patients who were on follow-up after radical cystectomy, and 7 patients who required restaging after chemotherapy.
Patients who underwent FDG-PET/CT, standard CT alone, bone scintigraphy, and histopathological examination were 44, 33, 36, and 44 respectively. For bladder tumor, the sensitivity of FDG-PET/CT was 88% as compared to 77% for that of CT, while the specificity was 25% as compared to 50% for that of CT. This could be due to confounding inflammation of bladder wall due to prior transurethral resection.
For lymph nodal disease the sensitivity of FDG-PET/CT was 57%, while that of CT was 33%. CT missed six muscle-invasive bladder cancers compared to four for FDG-PET/CT. FDG-PET/CT detected all three patients who had metastasis on bone scintigraphy.
The authors concluded that FDG-PET/CT is very specific for urinary bladder cancer metastasis, is more sensitive than CT and is as sensitive as bone scintigraphy. It might be the most cost-effective single method for pre-surgical staging and post-operative monitoring of patients with muscle invasive bladder cancer and to access the response to primary systemic chemotherapy.
Although the role of neo-adjuvant chemotherapy for muscle-invasive urothelial cancer of urinary bladder is controversial, , there is no controversy regarding its role in patients with pre-surgical evidence of metastasis.  The accuracy of pre-treatment staging, now done by CT or MRI can be improved by FDG-PET/CT. This would allow us to take more precise treatment decision. Addition of furosemide has given a new dimension to FDG-PET/CT by quickly eliminating the FDG from the bladder by forced diuresis, thus making structures and tumors easy to see against the tracer background. Another method to distinguish between normal and malignant tissue is by measuring the maximum standardized uptake values (SUV max ) of the radiotracer separately of normal urinary bladder and tumour. The SUVmax of normal tissue is low as compared to malignant tissue because of lesser metabolic activity. However, this parameter was not evaluated in this study.
PET scan involves radiation exposure of 5-7 mSv and when CT is combined with it then the dose increases to 23-26 mSv.  This should not be considered insignificant considering the fact that a chest X-ray exposes the patient to 0.02 mSv only and we are exposed to a annual background radiation of 2.2 mSv.  Therefore, FDG-PET/CT should be used judiciously. Further studies are needed to validate these observations.
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