Objective: To evaluate the feasibility of in-vivo quantitative susceptibility mapping (QSM) of the human kidney. Methods: An 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. Graph-cut-based unwrapping combined with the T₂*-IDEAL approach was performed to remove the chemical shift of fat and to quantify QSM of the upper abdomen. Mean susceptibility values of the entire, renal cortex and medulla in both kidneys and the liver were determined and compared. Five subjects were measured twice to examine the reproducibility. One patient with severe renal fibrosis was included in the study to evaluate the potential clinical relevance of QSM. Results: QSM was successful in 17 volunteers and the patient with renal fibrosis. 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. The results showed a good reproducibility. 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). Conclusion: QSM of the human kidney could be a promising approach for the assessment of information about microscopic renal tissue structure. Therefore, it might further improve functional renal MR imaging.

The hallmark of multiple myeloma (MM) is a clonal plasma cell infiltration in the bone marrow accompanied by myelosuppression and osteolysis. Premalignant stages such as monoclonal gammopathy of undetermined significance (MGUS) and asymptomatic stages such as smoldering myeloma (SMM) can progress to MM. Mesenchymal stromal cells (MSCs) are an integral component of the bone marrow microenvironment and play an important role in osteoblast differentiation and hematopoietic support. Although stromal alterations have been reported in MM contributing to hematopoietic insufficiency and osteolysis, it is not clear whether alterations in MSC already occur in MGUS or SMM. In this study, we analyzed MSCs from MGUS, SMM, and MM regarding their properties and functionality and performed messenger RNA sequencing to find underlying molecular signatures in different disease stages. A high number of senescent cells and a reduced osteogenic differentiation capacity and hematopoietic support were already present in MGUS MSC. As shown by RNA sequencing, there was a broad spectrum of differentially expressed genes including genes of the BMP/TGF-signaling pathway, detected already in MGUS and that clearly increases in patients with SMM and MM. Our data may help to block these signaling pathways in the future to hinder progression to MM.

Randomized controlled trials (RCT) are the driver of therapeutic innovations. However, it has been frequently shown that less than 5% of adult cancer patients enroll in clinical trials, although 70% of patients are considered as being willing to participate. Barriers to trial participation have been extensively studied. Although there is evidence that trial participation correlates with improved survival and reduced mortality, the rate of participation has not changed substantially. We provide retrospective data from a single-center analysis of 411 patients with multiple myeloma (MM) who were treated at the University Hospital Duesseldorf in Germany between January 2014 and December 2016. Each patient was analyzed for the real-world possibility of participating in a clinical study, based on the inclusion and exclusion (I/E) criteria and the recruiting period of open studies. The overall rate of study participation was 19%. A total of 53% of NDMM patients were eligible for first-line studies (GMMG-HD6, LenaMain). Of these, 80% consented to enrolment (42% of all). In contrast, only 38% of the RRMM population was eligible (GMMG-Relapse, Castor, Tourmaline, Admyre). Of these, only 22% (7% of all) consented. This was confirmed by virtual analysis, showing that only 29% of all RRMM patients would have been eligible for six internationally recruiting trials leading to later drug approval. The majority of cases were rendered ineligible by only one I/E criterion. The most common criteria were study-specific (prior therapies or refractory disease to a specific drug), kidney disease, and previous malignancy, followed by internal, neurologic, and infectious disease. In summary, this single-center analysis showed that I/E criteria permit study participation for most NNDM patients, with a dramatic decrease in the RRMM population. This is aggravated by the fact that the willingness for study participation also significantly declines in RRMM. Thus, addressing patient expectations and priorities seems to be the most promising approach to increasing patient enrollment in clinical trials.

In DWI, multi-exponential signal analysis can be used to determine signal underlying diffusion components. However, the approach is very complex due to the inherent low SNR, the limited number of signal decay data points, and the absence of appropriate acquisition parameters and standardized analysis methods. Within the scope of this work, different methods for multi-exponential analysis of the diffusion signal in the kidney were compared. To assess the impact of fitting parameters, a simulation was conducted comparing the free non-negative (NNLS) and rigid non-linear least square (NLLS) fitting methods. The simulation demonstrated improved accuracy for NNLS in combination with area-under-curve estimation. Furthermore, the accuracy and stability of the results were further enhanced utilizing optimized parameters, namely 350 logarithmically spaced diffusion coefficients within [0.7, 300] × 10⁻³ mm²/s and a minimal SNR of 100. The NNLS approach shows an improvement over the rigid NLLS method. This becomes apparent not only in terms of accuracy and omitting prior knowledge, but also in better representation of renal tissue physiology. By employing the determined fitting parameters, it is expected that more stable and reliable results for diffusion imaging in the kidney can be achieved. This might enable more accurate DWI results for clinical utilization.

Purpose: While ¹⁸F-FDG PET/CT yields valuable prognostic information for patients in first-line therapy of multiple myeloma (MM), its prognostic relevance in relapse is not established. Available studies of relapsed MM describe prognostic thresholds for frequently used PET/CT parameters that are significantly higher than those identified in the first-line setting. The purpose of this study was to evaluate the prognostic role of PET/CT in relapsed MM, based on parameters used in the first-line setting. Methods: Our retrospective study included 36 patients with MM who had received autologous or allogeneic stem cell transplantation, suffered at least one relapse, and underwent FDG-PET/CT at relapse. Number of focal bone lesions (FL), maximal standardised uptake value (SUVmax), and presence of PET-positive extramedullary lesions (EMD) were analysed. Results: For the number of FLs, the prognostic value was demonstrated with a cut-off of > 3 (median OS 3.8 months vs. not reached, p = 0.003). Median OS of patients with SUVmax ≤ 4 was not reached, while it was 3.9 months in patients with SUVmax > 4 (p = 0.014). Presence of EMD was a significant prognostic parameter too, with median OS of 3.6 months versus not reached (p = 0.004). The above-mentioned parameters showed prognostic significance for PFS as well. Combination of higher ISS stage and PET/CT parameters identified patients with particularly short OS (3.7 months vs. not reached, p < 0.001) and PFS (3.6 vs. 11.7 months p < 0.001). Conclusion: The PET/CT parameters SUVmax > 4, nFL > 3, and presence of EMD identify patients with poor prognosis not only in the first-line setting but also in relapsed MM.