ROLE OF BONE SCAN VERSUS CONVENTIONAL RADIOLOGY IN THE MANAGEMENT OF CANCER PATIENTS

1. ROLE OF BONE SCAN VERSUS CONVENTIONAL RADIOLOGY IN THE MANAGEMENT OF CANCER PATIENTS Dr.Lass G. Hawezi M.B.Ch.B., C.A.B.M.S., Ortho. Dr.Neyaz H. Ismail M.B.Ch.B., M. Sc. (N.M.) September 2011

2. SKELETAL SCINTIGRAPHY • Bone scintigraphy is the most frequently diagnostic study performed in most nuclear medicine laboratories. • It detects osteoblastic response in areas of metastatic deposits. • Bone scan performed with 99mTc-labelled diphosphonates has exquisite sensitivity for detection of skeletal pathology.

3. HISTORICAL BACKGROUND • First Chiewitz and Hevesy described using radionuclides to study the skeleton in 1935 using PHOSPHORUS-32 (P 32). • Fleming and colleagues in 1961 did the first clinical bone scan in human using STRONTIUM-85. • Blau used 18 F-FLUORIDE, as a scanning agent in 1962. • Subramanian and McAfee started the Modern era of skeletal imaging with the invention of 99mTc-labelled POLYPHOSPHATE in 1971. • In current practice, the agents of choice are 99mTc-labelled DIPHOSPHONATES.

4. RADIATION CONSIDERATIONS • The levels of radiation involved in most nuclear medicine studies are usually considerably lower than conventional x-ray study or CT scan. • Much of the radiation is eliminated through urine. • There is little absorbed dose to harm the patient.

5. COMPARATIVE EFFECTIVE DOSE RATES

6. THE NORMAL BONE SCAN • Most important feature of bone scan is symmetry about the midline. • There should be uniform tracer uptake throughout the skeleton with increased activity in the epiphyses of joints. • It varies markedly from children to that of adults. • Mild diffuse asymmetry in paired joints may be seen in adults, that correlate with handedness.

7. INTERPRETATION OF BONE SCAN • Multiple focal lesions irregularly scattered in axial skeleton is the typical feature of metastases. • Equivocal abnormalities detected in bone scan should be correlated with other imaging studies. • Solitary metastatic lesions are not uncommon finding. • Location may help in the differentiation.

8. SCINTIGRAPHIC PATTERN IN BONE METASTASES • Multiple focal lesions (typical). • Solitary focal lesions. • Diffuse skeletal involvement (super-scan). • Photon deficient (cold) lesions. • ‘Flare’ response or phenomenon. • Soft tissue lesions. • Normal (false negative) the scan may falsely appear normal.

9. BONE SCAN INTERPRETATION CRITERIA • An abnormal bone scan (with or without associated area of radiographic normality or evidence of metastases) was considered positive for metastases. • A normal bone scan or bone scan abnormality not suggestive of metastases (benign bone disease) associated with a benign radiographic findings was considered negative for metastases. (Castillo et al. 1985) and (Yamashita et al. 1991 and 1995)

10. METHODS • 99mTc – labeled MDP whole body bone scan was done for 481 patients in a one year period from 1st Feb. 2010 to 1st Feb. 2011. • 99mTc – labeled MDP was giving intravenously at a dose of 740 - 1110 MBq (20 - 30 mCi), and imaging was done after 2 - 4 hours of tracer injection by a double detector SPECT system gamma camera using low energy, high resolution collimator. • Abnormal bone scan were correlated with standard radiographs taken within days of the scan.

11. RESULTS

12. TYPE OF CANCER Type of Cancer, (n=481) Ca. Breast 59.4%, Ca. Prost. 11%, Sarcoma 8.7%, Ca Bronch. 4% and others 16.6%

13. RESULTS OF BONE SCAN Results of Bone Scan in Patients, (n=481) Abnormal scan (61.3%) to normal scan (38.6%) of cases.

14. DISEASE SPECIFIC RESULTS OF BONE SCAN Disease Specific results of Bone Scan, (n=481) Incidence of Abnormal in breast ca. (75.4%), Prostate (20.4%), Sarcoma (55.5%), Bronchus (53.8%) and others (66.6%)

15. RADIOLOGICAL FINDINGS IN CORRELATION TO BONE SCAN Radiological findings in correlation to Bone Scan, (n=481) No Radiological evidence of metastases (16.6%) of cases with bone scan shows evidence of multiple metastases. (5.6%) of cases had Abnormal radiology with normal bone scan results.

16. DISCUSSION • We notice that there is a high incidence of patient who had normal radiological investigation but showed abnormal bone scan result, this validates the high sensitivity of the test and encourage us to advice health care providers to conceder early Bone Scan specially for diseases that are readily metastasize to bone with or without radiological evidence of metastases.

17. DISCUSSION • There’s a high percentage of cases with abnormal bone scan with breast (75.4%), sarcoma (55.5), Bronchus (53.8) and prostate (20.6) cancer, that may be due long duration between primary diagnosis and the scan, and little number of cases do primary assessment for the state of metastases before initiation of the therapy.

18. CONCLUSION • High incidence of cases with normal radiological investigation but abnormal bone scan. • Very low false positive bone scan results. • High percentage of cases with abnormal bone scan.

19. RECOMMENDATION • So according to our data we highly recommend for every patients with cancer specially those who are readily metastasize to bone to do a primary assessment bone scan not only for early detection of the metastases but also to help interpretation of future follow up results and to detect non-radiologically apparent metastases and it’s important for radiotherapy planning and early detection of sites at risk for pathological fracture or spinal cord compression. • A large-scale study with larger sample size and correlation with skeletal survey, conventional radiology, bone biopsy and serum enzyme analysis may give more information about the status of skeletal metastases.

20. RECOMMENDATION • A primary assessment bone scan (Base line bone scan) for all cancers that spread to bone. • A large-scale study with larger sample size and correlation with skeletal survey, conventional radiology, bone biopsy and serum enzyme analysis.