Second, the presence of abdominal fat negatively impacts the estimation of the B0 field map, which is a critical step in the QSM algorithm.
First, respiratory movement of the upper abdominal organs leads to limited structural contrast and underestimated susceptibility values. However, to the best of our knowledge, there has been no adequate study performed in vivo to map susceptibility in the human kidney.Ībdominal QSM is considered technically challenging. demonstrated the sensitivity of QSM in detecting pathology caused by renal inflammation and fibrosis in mice. More recent studies in animal models have explored the potential of QSM to assess renal microstructure.
So far, QSM has mostly been applied to measure pathologic deposits in basal ganglia in various neurological diseases, or as an imaging biomarker of hepatic iron overload. In previous studies, QSM has been shown to be sensitive to changes in tissue microstructure or chemical composition and is, therefore, a promising, non-invasive approach for the assessment of renal interstitial fibrosis. Quantitative susceptibility mapping (QSM) is a novel MRI technique, which uses phase images to produce a high structural contrast and quantitative information of the magnetic susceptibility of the tissue. Since this diagnostic procedure is invasive, impaired by sampling bias and not arbitrarily repeatable, a non-invasive imaging modality able to accurately assess the degree of renal interstitial fibrosis is highly desirable. Up to now, the only reliable clinical tool to evaluate the degree of tubulointerstitial fibrosis is the renal biopsy. Therefore, interstitial fibrosis degree in the renal tissue is an important indicator in the determination of the reversibility of kidney damage. A histological hallmark of CKD, and a major cause of progressive renal function loss is the renal interstitial fibrosis. Several previous studies have demonstrated great potential of MRI biomarkers for characterizing different pathological processes involved in the progression of chronic kidney disease (CKD). In recent years, there has been an increasing research interest in functional renal MRI. Therefore, it might further improve functional renal MR imaging. QSM of the human kidney could be a promising approach for the assessment of information about microscopic renal tissue structure.
Besides, the mean renal QSM values obtained in healthy volunteers (0.04 ± 0.07 ppm for the right and − 0.06 ± 0.19 ppm for the left kidney) were substantially higher than that measured in the investigated fibrotic kidney (− 0.43 ± − 0.02 ppm). The results showed a good reproducibility. Anatomical structures in the abdomen were clearly distinguishable by QSM and the susceptibility values obtained in the liver were comparable to those found in the literature. QSM was successful in 17 volunteers and the patient with renal fibrosis. One patient with severe renal fibrosis was included in the study to evaluate the potential clinical relevance of QSM. Five subjects were measured twice to examine the reproducibility. Mean susceptibility values of the entire, renal cortex and medulla in both kidneys and the liver were determined and compared. Graph-cut-based unwrapping combined with the T 2*-IDEAL approach was performed to remove the chemical shift of fat and to quantify QSM of the upper abdomen. MethodsĪn axial single-breath-hold 3D multi-echo sequence (acquisition time 33 s) was completed on a 3 T-MRI-scanner (Magnetom Prisma, Siemens Healthineers, Erlangen, Germany) in 19 healthy volunteers. To evaluate the feasibility of in-vivo quantitative susceptibility mapping (QSM) of the human kidney.
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