Quantitative susceptibility mapping (QSM) has enabled MRI of tissue magnetic susceptibility to advance from simple qualitative detection of hypointense blooming artifacts to precise quantitative measurement of spatial biodistributions. QSM technology may be regarded to be sufficiently developed and validated to warrant wide dissemination for clinical applications of imaging isotropic susceptibility, which is dominated by metals in tissue, including iron and calcium. These biometals are highly regulated as vital participants in normal cellular biochemistry, and their dysregulations are manifested in a variety of pathologic processes. Therefore, QSM can be used to assess important tissue functions and disease. To facilitate QSM clinical translation, this review aims to organize pertinent information for implementing a robust automated QSM technique in routine MRI practice and to summarize available knowledge on diseases for which QSM can be used to improve patient care. In brief, QSM can be generated with postprocessing whenever gradient echo MRI is performed. QSM can be useful for diseases that involve neurodegeneration, inflammation, hemorrhage, abnormal oxygen consumption, substantial alterations in highly paramagnetic cellular iron, bone mineralization, or pathologic calcification; and for all disorders in which MRI diagnosis or surveillance requires contrast agent injection. Clinicians may consider integrating QSM into their routine imaging practices by including gradient echo sequences in all relevant MRI protocols.

The normative diffusion values of the human median nerve can be used as a reference in evaluation, diagnosis, and follow-up of entrapment, trauma, and regeneration of the median nerve.

Purpose To assess the reproducibility of brain quantitative susceptibility mapping (QSM) in healthy subjects and in patients with multiple sclerosis (MS) on 1.5 and 3T scanners from two vendors. Materials and Methods Ten healthy volunteers and 10 patients were scanned twice on a 3T scanner from one vendor. The healthy volunteers were also scanned on a 1.5T scanner from the same vendor and on a 3T scanner from a second vendor. Similar imaging parameters were used for all scans. QSM images were reconstructed using a recently developed nonlinear morphology-enabled dipole inversion (MEDI) algorithm with L1 regularization. Region-of-interest (ROI) measurements were obtained for 20 major brain structures. Reproducibility was evaluated with voxel-wise and ROI-based Bland–Altman plots and linear correlation analysis. Results ROI-based QSM measurements showed excellent correlation between all repeated scans (correlation coefficient R ≥ 0.97), with a mean difference of less than 1.24 ppb (healthy subjects) and 4.15 ppb (patients), and 95% limits of agreements of within −25.5 to 25.0 ppb (healthy subjects) and −35.8 to 27.6 ppb (patients). Voxel-based QSM measurements had a good correlation (0.64 ≤ R ≤ 0.88) and limits of agreements of −60 to 60 ppb or less. Conclusion Brain QSM measurements have good interscanner and same-scanner reproducibility for healthy and MS subjects, respectively, on the systems evaluated in this study.

This study was carried out to identify the distinguishing features of brucellosis on magnetic resonance imaging (MRI). MRI examinations were performed in 14 patients with spinal brucellosis. A 1-T Magnetom (Erlangen, Siemens) was used to obtain T1-weighted (TR/TE 500/30) and T2-weighted (TR/TE 2000/80/20) spin echo sequences, in both sagittal and axial planes. Thirty-three percent of the vertebrae and 18 levels of disc were involved in the 14 brucellar spondylitis cases. Eleven patients (79.8%) with discitis revealed anterior superior vertebral body involvement. Fourteen (77.7%) of the levels with discitis displayed soft tissue swelling without presence of abscess formation. Seven facet joints of five patients with discitis displayed signal increase after contrast enhancement. Vertebral body signal changes without morphologic changes marked signal increase in the intervertebral disc on T2-weighted and contrast-enhanced sequences, and soft tissue involvement without abscess formation can be accepted as specific MRI features of brucellar spondylitis. The facet joint signal changes following contrast enhancement is another MRI sign of spinal brucellosis, which has not been mentioned so far.

Purpose To investigate the magnetic susceptibility of intracerebral hemorrhages (ICH) at various stages by applying quantitative susceptibility mapping (QSM). Materials and Methods Blood susceptibility was measured serially using QSM after venous blood withdrawal from healthy subjects. Forty-two patients who provided written consent were recruited in this institutional review board approved study. Gradient echo MRI data of the 42 patients (17 females; 64±12 yrs) with ICH were processed with QSM. The susceptibilities of various blood products within hematomas were measured on QSM. Results Blood susceptibility continually increased and reached a plateau 96 hours after venous blood withdrawal. Hematomas at all stages were consistently hyperintense on QSM. Susceptibility was 0.57 ± 0.48, 1.30 ± 0.33, 1.14 ± 0.46, 0.40 ± 0.13, and 0.71 ± 0.31 parts per million (ppm) for hyperacute, acute, early subacute, late subacute and chronic stages of hematomas respectively. The susceptibility decrease from early subacute (1.14ppm) to late subacute (0.4ppm) was significant (p<0.01). Conclusion QSM reveals positive susceptibility in hyperacute hematomas, indicating that even at their hyperacute stage, deoxyhemoglobin may exist throughout the hematoma volume, not just at its rim as seen on conventional T2* imaging. QSM also reveals reduction of susceptibility from early subacute to late subacute ICH, suggesting that methemoglobin concentration decreases at the late subacute stage.