Since I am not shy of any responses-
- Bone island threshold- dont use at all- trabeculated border, near joint, elongated shape- most importantly- same density as cortex or higher as its pure calcium vs. tumor has mixture fo stuff. MRI- black on t1/t2, or white border on t1, no reaction around it-Quant parameter- no or minimal enhancement. Little white signal on t2 is ok. Caveat- Bone islands also grow in acromegaly or on growth hormones.
- In-Opp phase- T1 dixon/csi=20%- can use above 16%; T2 Dixon= 26%, but usually red marrow drops more than 50%- where it doesnt work- sclerotic lesions like prostate or hemorrhagic lesion or underlying serous marrow atrophy/SCD- you can attend bone marrow talk I will give on behalf of Dr. Stacy Smith in ARRS
- ADC=for soft tissue lesions- use 1.1 or lower for malig, 1.1-1.5 for in b/w, >1.5 benign. Its in ST-RADs paper. Do not read ADC in isolation but with conv imaging. ADC doesnt work for CS , liposarcoma and myxoid lesions. Still works for hemorragic tumors. All it tells you is cellularity which correlates with malig but not benign/malig. OT-RADS- different way it behaves- its actually enhancement of marrow- more with benign lesions and less so with malignant. Best it works with is with round cell tumros- lowest ADC of 0.5-0.8. Our paper on OT-RADs with DWI should be out this month in pubmed. Basically- OT-RADS can be done without DWI with similar reliability and accuracy of readers. DWI however may incr. confidence somewhat and values are diff. b/w benign vs. malig. Lastly ADC doesnt help much in differentiating among diff soft tissue sarcomas.
Some articles for your reading pelasure-
Sasiponganan C, Yan K, Pezeshk P, Xi Y, Chhabra A. Advanced MR imaging of bone marrow: quantification of signal alterations on T1-weighted Dixon and T2-weighted Dixon sequences in red marrow, yellow marrow, and pathologic marrow lesions. Skeletal Radiol. 2020 Apr;49(4):541-548. doi: 10.1007/s00256-019-03303-z. Epub 2019 Oct 12. PMID: 31606776.
Gowda P, Bajaj G, Silva FD, Ashikyan O, Xi Y, Chhabra A. Does the apparent diffusion coefficient from diffusion-weighted MRI imaging aid in the characterization of malignant soft tissue tumors and sarcomas. Skeletal Radiol. 2023 Feb 2. doi: 10.1007/s00256-023-04289-5. Epub ahead of print. PMID: 36725723.
Chhabra A, Gupta A, Thakur U, Pezeshk P, Dettori N, Callan A, Xi Y, Weatherall P. Osseous Tumor Reporting and Data System-Multireader Validation Study. J Comput Assist Tomogr. 2021 Jul-Aug 01;45(4):571-585. doi: 10.1097/RCT.0000000000001184. PMID: 34270485.
Here is the OT-RADS III case – hot off the press- two presumably notochonrdal rests- 3 and 8mm each in coccyx.
OT-RADS: III. Probably benign osseous tumor. Recommend surveillance imaging at 3, 6, 12, and 24 months. If the lesion regresses or resolves, surveillance can be terminated if felt clinically appropriate.
I could have called it OT-RADS II if I had some prior imaging.
