Slide 1

Diagnostic importance of contrast enhanced 18 F- fluorodeoxyglucose positron emission computed tomography (FDG PET-ceCT) in patients with tumor induced phosphaturic osteomalacia Our experience. Abstract Id: IRIA-1225 Slide 2 AIM To assess the diagnostic utility of FDG PET-ceCT in localisation of tumours in patients with clinical diagnosis of tumor induced phosphaturic osteomalacia (TIO) To correlate PET-ceCT findings with histopathological results. Slide 3 MATERIALS AND METHODS Prospective study of 8 patients (M/F: 5/3, mean age: 42 yrs, range: 24-60 yrs) with clinical diagnosis of TIO referred for body FDG PET-ceCT scans. Whole body (head to toe + upper limbs) PET-ceCT scans were acquired on Philips GEMINI TOF PET-CT scanner with 64 slice CT scanner following a standard protocol. 5 /8 patients had estimation of serum FGF-23 levels. FDG PET-ceCT findings were correlated with postoperative histology findings and clinical follow up. Slide 4 RESULTS FDG PET-ceCT localised site of tumor in 7/8 patients Sensitivity 87.5%, Positive predictive value 100% 1 patient had atypical presentation, the site of tumor was localised in conjunction with 68 Ga DOTANOC PET-CT Site: Bone 3/8 patients, Craniofacial 5/8 patients All the patients had phosphaturic mesenchymal tumor on histolopathological examination. FDG PET-ceCT & HPE were concordant in 7/8 patients. Slide 5 RESULTS - BIOCHEMICAL PARAMETERS Biochemical parameters Pre- operative Post- operative P value (Wilcoxon Signed ranks test) S. Calcium (mg/dl) 8.2 (7.92-8.45) 9.5 (8.97-9.95) 0.012 S. Phosphorus (mg/dl) 1.15 (0.75-1.5) 3.10 (2.72-3.85) 0.012 S. FGF 23 (RU/mL) 1620 (1434-2858) 152 (69.5-169.0) 0.043 Slide 6 CASE 1 H/o polyarthritis for 7 years and progressive weakness of all 4 limbs with wasting of muscles for 5 years Bed ridden for 5-6 years RA factor & HLA B27negative S. Calcium8.2 mg/dl S. Phosphorus1.1 mg/dl S. FGF 231620 RU/ml S. 1, 25 dihyroxy vitamin D314 pg/ml S. ALP679 U/L S. PTH171.8 pg/ml S. potassium4.0 mEq/L Slide 7 99m Tc-MDP WHOLE BODY BONE SCINTIGRAPHY Slide 8 18 F-FDG PET-ceCT WHOLE BODY SCAN MIP IMAGE SUVmax 5.2 Slide 9 Biopsy spindle cell neoplasm with pericytomatous features. The possibilities include glomangiopericytoma (Sinonasal type hemangiopericytoma, hemangiopericytoma like tumor) Slide 10 CASE 2 H/o weakness and pain in bilateral hips for 2 years, difficulty in walking S. Calcium9.8 mg/dl S. Phosphorus1.5 mg/dl S. FGF-233360 RU/ml S. ALP384 U/L S. I, 25 dihyroxy vitamin D310 pg/mL S. PTH44 pg/mL S. Creatinine0.8 mg/dl 24 hour urine inorganic phosphorus 0.5g/24 hours Slide 11 99m Tc-MDP WHOLE BODY BONE SCINTIGRAPHY Slide 12 18 F-FDG PET-ceCT WHOLE BODY SCAN MIP IMAGE SUVmax 4.4SUVmax 5.7 SUVmax 5.4 Slide 13 CASE 2 Patient underwent tonsillectomy. (HPE reactive lymphoid follicles.) Curettage and bone grafting was done for lesion in right greater trochanter. (HPE fragmented atypical spindle cells) S. Phosphorus transiently increased to 2mg/dl after surgery, following which again it dropped to 1.5 mg/dl Resistance to treatment with Tab. Shelcal 68 Ga DOTANOC PET-ceCT was planned for further localisation since this tumors express somatostatin receptors Slide 14 68 Ga DOTANOC PET-ceCT WHOLE BODY SCAN MIP IMAGE Slide 15 HPE Bony trabeculae with nests of cellular nodules composed of bland spindle and epitheloid cells and moderate cytoplasm arranged around blood vessels. Slide 16 REVIEW OF LITERATURE NoAuthorNResults 1. Jadhav S et al (2014) 16 FDG PET-CT positivity 50% Gallium DOTATATE PET-CT positivity 100% 2. Chong WH et al (2013) 31 FDG PET-CT sensitivity 88 %, Octreo-SPECT sensitivity- 0.95% 3. Shamim SA et al (2010) 15 FDG PET-CT positivity - 9/15 patients 4. Our study with TOF PET-ceCT (64 slice) scanner 8Sensitivity 87.5% Slide 17 CONCLUSION 18F-FDG PET-ceCT is a sensitive modality for localisation of tumors in patients with TIO Since these tumors are small in size and can be located anywhere in body, whole body (head to toe+ upper limbs) acquisition should be performed. Careful scrutiny of appendicular skeleton should be performed in the scans 18F-FDG PET-ceCT can serve as a first line imaging modality in TIO, to facilitate early diagnosis as 68 Ga- DOTANOC PET-CT facility is not readily available. Slide 18 Clinical diagnosis of TIO (thorough clinical history, biochemical parameters, exclude familial forms) 18 F-FDG PET-ceCT whole body scan (head to toe + upper limbs) + - + - Surgery & clinical monitoring Medical therapy MRI (regional) 68 Ga-DOTANOC PET-CT PROPOSED FLOWCHART