Multiple myelomas is a malignant hematological disorder characterized by the clonal proliferation of plasma cells and the infiltration of bone marrow. Diagnostic imaging plays a pivotal role in staging, restaging, prognosis and treatment monitoring of Multiple Myeloma (MM).
WB-MRI is superior to PET/CT in the diagnosis of diffuse infiltrative bone marrow disease, while PET is more sensitive in the detection of disease recurrence after therapy. PET/CT has been shown to provide complementary information to WB-MRI at staging. Both modalities are currently included in the Salmon-Durie plus staging system.
With the introduction of PET/MRI, the radiation exposure component of CT previously accrued in PET/CT studies can be eliminated. In a post-therapy setting, particularly in aggressive forms with a poor
prognosis, a combination of both modalities (PET/MRI) is preferable. In lymphoma, the PET of PET/MRI or PET/CT provides information about tumor burden in the whole body that usually needs to be followed up with serial studies. With the introduction of simultaneous PET/MRI, there is a drastic reduction in radiation exposure compared to PET/CT, particularly in those requiring serial follow-ups while providing improved information on bone marrow and soft tissue.
46-year-old male with H/o chronic back pain.
Sagittal T1 (A), STIR (B), PET/MRI fused (C) and Coronal STIR (D) images showing the entire visualized axial and appendicular skeleton studded with multiple focal and infiltrative marrow lesions with focal FDG uptake in L1 vertebra (white arrows), in a right-sided rib and L5 vertebrae on the Coronal whole-body PET MIP image (red arrows) consistent with Multiple Myeloma. The disease the burden is more accurately depicted on MRI.
78 year old male presented with pain in the right hip. Investigated elsewhere with MRI which revealed a lesion in the right acetabulum, metastatic with tiny focal marrow lesions in the spine. Referred for a PET/MRI scan to look for a possible primary.
WB PET /MRI revealed an FDG avid focal marrow lesion in the right acetabulum. In addition, multiple tiny non avid marrow lesions were seen in multiple vertebral bodies in the spine(A, B, C) and in the pelvic bones including the left femur (D, E). There was no other metabolically active abnormality elsewhere in the whole body suggesting it to be a primary bone pathology and a possibility of multiple myeloma was suspected.
Considering a scenario in which a whole-body PET CT would have been done, a solitary avid bony lesion would have raised the possibility of a plasmacytoma. Identification of though non-avid focal marrow lesions in the spine placed it in a multiple myeloma category thus upstaging the disease.
63 Year Old Male, known case of multiple myeloma, Pre & Post Chemotherapy scans.
Pre Chemotherapy Sagittal T1 Weighted image(A) of the entire spine reveals, infiltrative and focal marrow lesions in the entire spine with collapse at D9 with diffuse FDG uptake on PET(B) and PET MR fused image (C).
Post Chemotherapy (A) Sagittal T1W images show regression in marrow infiltration much obvious on MR. (B) PET sagittal ( C) PET MR fused image showing complete metabolic response.
1. The radiographic skeletal survey has been the mainstay of multiple myeloma imaging and continues to be recommended for baseline evaluation. Bone scintigraphy is not useful because the disease process in multiple myeloma inhibits osteoblastic activity. Advanced imaging with MRI has been found to be more sensitive in identifying bone lesions and along with multidetector CT and FDG PET may alter staging in 15 to 25% of patients with multiple myeloma and therefore recently published guidelines recommend whole-body MR for the patient who has MGUS or normal skeleton survey. PET aids in the identification of active multiple myeloma on the basis of FDG uptake and MRI imaging helps identify MM from its replacement of normal fat within the bone marrow which occurs in patterns that correlate with the disease stage. It may also be useful for better visualization of the extramedullary disease, sites of pain, or focal lesions for the purpose of biopsy or radiation treatment.
2. Moreover, since lytic lesions may not heal, a radiographic survey has no role in monitoring the response to treatment. There is no currently recommended protocol regarding post-treatment imaging of patients with multiple myeloma, but multidetector CT, MR and FDG PET have been found to be useful in patients with symptoms.
3. PET/MR brings together the specificity of PET with the sensitivity of MR imaging not only for initial staging but also for prognostication and assessment of treatment response.
Case Study Prepared by:
This short PET-MRI Scan case was compiled by Dr. Sangeeta Taneja and Dr. Amarnath Jena (Nuclear Medicine Physician at PET-Suite @ Indraprastha Apollo Hospital, Sarita Vihar).
Read More about PET-MRI Scan at House Of Diagnostics in Delhi and NCR.
The Simultaneous PET-MRI Scan is currently offered at PET-Suite at Apollo Hospital, Sarita Vihar.