Hybrid imaging
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PET-MRI is a hybrid imaging technique that was approved by the FDA in 2011. It provides both the anatomical details from MRI and the functional and metabolic information from PET. There are two main types of PET-MRI scanners: simultaneous and sequential. Implementation of PET-MRI presents challenges related to PET detector elements, attenuation correction, and system corrections. PET-MRI shows potential for use in neurology, oncology, pediatrics, cardiology, and musculoskeletal imaging by providing more biological and functional data than PET-CT without radiation exposure. Examples of clinical applications include detecting tumor recurrence, evaluating treatment response, and replacing painful bone marrow biopsies for lymphoma.
Hybrid imaging
- 1. PET-MRI HYBRID IMAGING A different spin from under the rim DR. MITUSHA VERMA DEPT. OF RADIODIAGNOSIS DR.B.NANAVATI HOSPITAL MUMBAI.
- 2. A NEW PAGE ADDED TO HISTORY OF IMAGING…. PET / MRI approved by FDA in June 2011. In these two years, The technology continue to struggle with learning how to integrate the system with workflow. Comparing the utility of PET/MRI versus PET/CT. Determining which organs and disease processes are best imaged with PET/MRI
- 3. PRINCIPLE OF PET: Coincidence Detection
- 4. Structural MRI Functional MRI PET MRI Metabolic PET Perfusion Spectroscop y Dynamic MR CONCEPT OF MRI-PET
- 5. Excellent human anatomical information. Superior soft tissue characterization. Better temporal resolution. Less Radiation Hazards. HIGHLIGHTS OF MRI-PET
- 6. TYPES OF SCANNERS Simultaneous Scanners Sequential Scanners
- 7. CHALENGES IN IMPLEMENTATION PET detector element related issues. Attenuation correction related issue. System Correction.
- 8. PET DETECTOR ELEMENT RELATED ISSUES Strategies to limit the interference of the magnetic field of the MRI scanner, with the detection of the PET signal In terms of the ideal detector crystal, Lutetium oxyorthosilicate (LSO) and Bismuth germinate (BGO) have - least susceptible to MR artifacts. Using optical fibers that guide light away from the magnetic field Replacing the PMT with avalanche photodiode devices (APDs) Shielding the PMT from the surrounding magnetic field
- 9. INDICATIONS FOR MRI-PET Neurology – Dementia Epilepsy Stroke Imaging Oncology - Brain Tumours Pelvic Tumours Head and Neck Tumours Lymphoma Sarcoma Langerhans cell histiocytosis Breast Cancers Pediatric Imaging. Cardiac Imaging. Musculoskeletal Imaging.
- 10. 75- year old female, presented with left breast lump. FNAC from the lump showed atypical cells. Dynamic post contrast axial MIP image Spiculated mass with intense FDG uptake. FDG non avid small nodular enhancing lesion detected in the right breast detected on MR I
- 11. FDG avid metabolically active marrow lesion in the left pubic bone: definitive osseous metastasis
- 14. 44 year old male, known case of left temporal low grade Glioma operated upon 6 years back with post-operative RT has now presented with suspected recurrence. Simultaneous PET MRI provided information regarding FDG uptake, rCBV, rCBF, Choline/Creatine and Choline/ NAA ratio from each tissue element at the same time, making a diagnosis of recurrence accurately that subsequently proved on histology following resurgery.
- 16. “With PET/CT, we’ve been able to localize things. Now we can give more precise location with MRI than with CT. MRI has the capability of doing functional imaging, combined with physiology-based imaging of PET. We’ve doubled the amount of things we can see with this.” “Since MRI provides more biological and functional data than CT — without radiation —the system is a huge advantage for pediatric patients and those needing multiple scans”
- 17. If a tumor is shown to be metabolically active via PET, but shows poor tissue perfusion, does this have management implications for chemotherapeutic regimens? Should a physician change the chemo treatment if the patient has a cancer without enough blood flow? Another topic is lymphoma treatment. MRI is good at detecting bone marrow edema, which indicates that lymphoma is spreading to the bones. Patients with lymphoma often receive PET scans as well as bone marrow biopsies. Can a PET/MRI offering information about marrow edema replace a painful biopsy?
- 18. Macromolecular information (in micromolar quantities through MR spectroscopy, perfusion imaging, cell migration imaging, with iron labeling and oxygen consumption imaging, with 17O among others) can now be combined with the picomolar detail that metabolic imaging with PET provides.
- 19. “We don’t think (PET/MRI) will replace PET/CT for older adults who have cancers easily worked up by PET/CT, but selected applications like pediatric malignancies, pelvic malignancies, head and neck cancer, those areas are going to be extremely exciting.”
- 20. THANK YOU….
Editor's Notes
- #4: As the radioisotope undergoes positron emission decay (also known as positive beta decay), it emits a positron, an antiparticle of the electron with opposite charge. After travelling up to a few millimeters the positron encounters an electron. The encounter annihilates them both, producing a pair of annihilation (gamma) photons moving in opposite directions.