Initial experience with positron coincidence dual head gamma camera with high resolution CT-fusion and attenuation correction

Aim: To Study The Clinical Utility Of Dual Head Coincidence Gamma Camera Pet In Private Hospital Practice And To Determine The Feasibility Of Registering Coincidence Images With High-Resolution Ct Images For Lesion Localization And Attenuation Correction. Methods :Thirty Patients Were Studied On A Dual Head Coincidence Gamma Camera With 1' Nai Crystal 1 Hour After I.V Injection Of 18f-Fdg. Among These, 25 Were Referred For Oncological Indications (Hodgkin'S Disease - 5, Non Hodgkin'S Lymphoma - 2, Ca. Breast - 5, Ca-Colon 3, Ca Lung 2, Sarcomas 2, Ca Nasopharynx 1, Ca Ovary 1, Suspected Malignancy 3 And Occult Primary 1), 3 Were For Neurological (Neuro Degenerative Disease) And 2 Were For Cardiac (Myocardial Viability) Indications. All Patients Underwent High Resolution Ct (Whole Body For Oncology Patients, Chest For Cardiac Patients And Brain For Neurological Patients), On A Different Ct Scanner One Hour Before 18f - Fdg Injection. 10 Mci Of 18f-Fdg Was Injected To The Patients After Overnight Fast (1 Hour Post Oral Glucose Loading For Cardiac Patients) And After Estimating Blood Sugar. Acquired Data Were Rebinned With Fourier Rebinning And Reconstructed With An Iterative Reconstruction Algorithm Based On Coincidence Ordered Subsets Expectation Maximization (Cosem). These Reconstructed Images Were Fused With The Ct Images hnported Through Hospital Network. Ct Based Attenuation Map Was Determined And Applied To Get Attenuation Corrected Images. Both Non-Corrected And Corrected Images Were Interpreted By Fusing Them With Ct Images. Findings Are Compared With Those Of Physical Examination, Computed Tomography And Histopathology. Results: Among 25 Oncology Patients, Positive Scans For Active Disease Were Found Tn 16 Patients. Eight Patients Were Referred To Evaluate Response To Therapy And Failure Of Response Was Demonstrated In All Of Them. Ten Patients Were For Staging Of Disease, In-Operable Disease Was Demonstrated In 6 of Them. Three Patients Were For Recurrence, Of These One Patient Was Demonstrated To Have Recurrence. Four Patients Were Referred For Suspected Malignant Pathology, Only One Patient Was Detected To Have Malignancy. Non-Attenuation Corrected Images Demonstrated All The Lesions And Attenuation Corrected Images Did Not Add To Lesion Detectablity. Ct Image Fusion Greatly Increased The Confidence In Exact Anatomical Lesion Localization. Conclusion: Coincidence Pet With Dual Head Gamma Camera Was Found Very Useful In Following Up The Response To Therapy In Oncology Patients. 1. Non-attenuation corrected images were as good as attenuation corrected images in lesion detection. Fusion with CT-images increased confidence of anatomical localization. 2. Attenuation correction using CT-images from different scanner is difficult as exact image fusion is difficult to obtain. Dual head coincidence PET is an acceptable, cost effective alternative till dedicated PET becomes affordable. (authors)