QSM Throughout the Body

Abstract

Magnetic materials in tissue, such as iron, calcium, or collagen, can be studied using quantitative susceptibility mapping (QSM). To date, QSM has been overwhelmingly applied in the brain, but is increasingly utilized outside the brain. QSM relies on the effect of tissue magnetic susceptibility sources on the MR signal phase obtained with gradient echo sequence. However, in the body, the chemical shift of fat present within the region of interest contributes to the MR signal phase as well. Therefore, correcting for the chemical shift effect by means of water‐fat separation is essential for body QSM. By employing techniques to compensate for cardiac and respiratory motion artifacts, body QSM has been applied to study liver iron and fibrosis, heart chamber blood and placenta oxygenation, myocardial hemorrhage, atherosclerotic plaque, cartilage, bone, prostate, breast calcification, and kidney stone.

Maximum spherical mean value filtering for whole‐brain QSM

“…Fifth, the simulation reconstruction slopes for PDF + MEDI‐SMV and PDF + MEDI‐mSMV varied with SNR, suggesting that susceptibility values are somewhat lower than for PDF—the exact cause of this remains to be elucidated. Finally, the application of mSMV here is limited to the brain, which is important for studying many neurological diseases including Alzheimer's disease, 49 Parkinson's disease, 23 amyotrophic lateral sclerosis, 22 and MS, 50 but mSMV may be extended to the body outside the brain 51 with the consideration of chemical shift of fat 52 …”

Quantitative susceptibility mapping for detection of kidney stones, hemorrhage differentiation and cyst classification in ADPKD

“…Data acquisition for QSM is easily implementable on any clinical platform and does not require special hardware or sequences [17,56].…”

“…Susceptibility maps are extracted from multi-echo gradient echo (GRE) images through spatial deconvolution according to the dipole field model in magnetism physics [19,20]. QSM differentiates calcifications from hemorrhages and protein deposition on the basis of their magnetic properties [18,[21][22][23]. Despite the major potential benefits of QSM in assessment of ADPKD pathology, incorporating QSM into clinical abdominal imaging remains a challenge due to time constraints, respiratory motion, chemical shift of fat and strong magnetic field inhomogeneity within the abdomen and pelvis [22].…”

Value of Quantitative Susceptibility Mapping in Clinical Neuroradiology

“…102 Outside the Brain QSM has also been applied to the regions outside the brain. 103 Applications of QSM are currently limited, but future progress is expected.…”