True phase quantitative susceptibility mapping using continuous single‐point imaging: a feasibility study

Abstract

Purpose In this study, we explore the feasibility of a new imaging scheme for quantitative susceptibility mapping (QSM): continuous single‐point imaging (CSPI), which uses a pure phase encoding strategy to achieve true phase imaging and improve QSM accuracy. Methods The proposed CSPI is a modification of conventional SPI to allow acquisition of multiple echoes in a single scan. Immediately following a phase encoding gradient, the free induction decay is continuously sampled with extremely high temporal resolution to obtain k‐space data at a fixed spatial frequency (i.e., at a fixed k‐space coordinate). By having near‐0 readout duration, CSPI results in a true snapshot of the transverse magnetization at each TE. Additionally, parallel imaging with autocalibration is utilized to reduce scan time, and an optional temporal averaging strategy is presented to improve signal‐to‐noise ratio for objects with low proton density or short T2* decay. The reconstructed CSPI images were input to a QSM framework based on morphology enabled dipole inversion. Result In an experiment performed using iron phantoms, susceptibility estimated using CSPI showed high linearity (R2 = 0.9948) with iron concentration. Additionally, reconstructed CSPI phase images showed much reduced ringing artifact compared with phase images obtained using a frequency encoding strategy. In an ex vivo experiment performed using human tibia samples, estimated susceptibilities ranged from –1.6 to –2.1 ppm, in agreement with values reported in the literature (ranging from –1.2 to –2.2 ppm). Conclusion We have demonstrated the feasibility of using CSPI to obtain true phase images for QSM.

Advanced magnetic resonance imaging of cartilage components in haemophilic joints reveals that cartilage hemosiderin correlates with joint deterioration

“…These findings suggest a need not only to study molecular pathways of cartilage iron loading and retention, but also to develop and validate sensitive MRI iron quantification methodologies specific to cartilage or other joint tissues for more immediate clinical application. A number of novel quantitative MRI techniques are in development which, if adjusted for cartilage imaging, may provide sensitive methods to precisely quantify cumulative joint iron loading over time. Quantitative iron imaging would revolutionize the ability to recognize the consequences of subclinical bleeding and/or suboptimal treatment strategies in haemophilia.…”

Magnetic Resonance Imaging of Hard Tissues and Hard Tissue Engineered Bio-substitutes

“…Although SPI method has been widely used for special purposes, such as studying solids, removing susceptibility artifacts, and chemical shifts artifacts, long acquisition time was the main limitation. Conventional SPI has been recently implemented to enable continuous imaging with a more time-efficient acquisition (CSPI, continuous single-point imaging) [108].…”

Ultrashort echo time quantitative susceptibility mapping (UTE‐QSM) for detection of hemosiderin deposition in hemophilic arthropathy: A feasibility study

“…In the literature, QSM has been investigated extensively in neuro, [20][21][22] body, 23,24 cardiovascular, 25 and MSK imaging. [15][16][17][18] QSM may be a promising technique for HA, given its ability to quantify iron level in tissues. Its application in HA diagnosis would permit quantification of hemosiderin deposition without administration of exogenous contrast agent.…”

“…28 The combination of UTE MR imaging and QSM analysis has allowed estimation of susceptibilities of short T * 2 tissues such as cortical bone, tendon, and ligament. 17,18 However, it is unclear whether the UTE-QSM technique can be used to estimate susceptibility of hemosiderin in the joints of patients with HA.…”