Early response assessment in patients with multiple myeloma during anti-angiogenic therapy using arterial spin labelling: first clinical results

Comparison of reduced field-of-view DWI and conventional DWI techniques for the assessment of lumbar bone marrow infiltration in patients with acute leukemia

Objectives

To compare the imaging quality, apparent diffusion coefficient (ADC), and the value of assessing bone marrow infiltration between reduced field-of-view diffusion-weighted imaging (r-FOV DWI) and conventional DWI in the lumbar spine of acute leukemia (AL).

Methods

Patients with newly diagnosed AL were recruited and underwent both r-FOV DWI and conventional DWI in the lumbar spine. Two radiologists evaluated image quality scores using 5-Likert-type scales qualitatively and measured signal-to-noise ratio (SNR), contrast-to-noise (CNR), signal intensity ratio (SIR), and ADC quantitatively. Patients were divided into hypo- and normocellular group, moderately hypercellular group, and severely hypercellular group according to bone marrow cellularity (BMC) obtained from bone marrow biopsies. The image quality parameters and ADC value between the two sequences were compared. One-way analysis of variance followed by LSD post hoc test was used for the comparisons of the ADC values among the three groups. The performance of ADC obtained with r-FOV DWI (ADCr) and conventional DWI(ADCc) in evaluating BMC and their correlations with BMC and white blood cells (WBC) were analyzed and compared.

Results

71 AL patients (hypo- and normocellular: n=20; moderately hypercellular: n=19; severely hypercellular: n=32) were evaluated. The image quality scores, CNR, SIR, and ADC value of r-FOV DWI were significantly higher than those of conventional DWI (all p<0.05), and the SNR of r-FOV DWI was significantly lower (p<0.001). ADCr showed statistical differences in all pairwise comparisons among the three groups (all p<0.05), while ADCc showed significant difference only between hypo- and normocellular group and severely hypercellular group (p=0.014). The performance of ADCr in evaluating BMC (Z=2.380, p=0.017) and its correlations with BMC (Z=-2.008, p = 0.045) and WBC (Z=-2.022, p = 0.043) were significantly higher than those of ADCc.

Conclusion

Compared with conventional DWI, r-FOV DWI provides superior image quality of the lumbar spine in AL patients, thus yielding better performance in assessing bone marrow infiltration.

Imaging Techniques and Clinical Application of the Marrow-Blood Barrier in Hematological Malignancies

The pathways through which mature blood cells in the bone marrow (BM) enter the blood stream and exit the BM, hematopoietic stem cells in the peripheral blood return to the BM, and other substances exit the BM are referred to as the marrow-blood barrier (MBB). This barrier plays an important role in the restrictive sequestration of blood cells, the release of mature blood cells, and the entry and exit of particulate matter. In some blood diseases and tumors, the presence of immature cells in the blood suggests that the MBB is damaged, mainly manifesting as increased permeability, especially in angiogenesis. Some imaging methods have been used to monitor the integrity and permeability of the MBB, such as DCE-MRI, IVIM, ASL, BOLD-MRI, and microfluidic devices, which contribute to understanding the process of related diseases and developing appropriate treatment options. In this review, we briefly introduce the theory of MBB imaging modalities along with their clinical applications.

Mid-term response assessment in multiple myeloma using a texture analysis approach on dual energy-CT-derived bone marrow images - A proof of principle study

PURPOSE

To identify textural features on dual-energy CT (DECT)-generated virtual non calcium (VNC) bone marrow images in a small group of patients with multiple myeloma undergoing systemic treatment which could potentially help for mid-term response assessment.

METHODS

44 patients (59.1 ± 11.2 yr.) with multiple myeloma who underwent unenhanced whole-body reduced-dose DECT before and after systemic therapy were evaluated. All patients had current hematologic laboratory tests including serum levels of immunoglobulins, albumin, and total proteins. Using DECT post-processing, bone marrow images of the axial skeleton were reconstructed. The vertebral bodies T10-L5 were segmented for quantification of 1st order (n = 18) and 2nd order Gray Level Co-occurrence Matrix (GLCM) textural features (n = 23) based on an open-source radiomics library (Pyradiomics), which were then compared with the hematologic response category to treatment. Five patients underwent only active surveillance at intervals after previous successful therapy.

RESULTS

According to hematologic diagnosis, 29 patients were classified as complete response (CR), 10 as partial response (PR) and 5 as stable disease (SD). We observed a significant drop of the 1st order textural features "10th percentile" (p = 0.009), "median" (p = 0.01), and "minimum" (p < 0.0001) after treatment, whereas the 1st order feature "range" (p = 0.0004) and the 2nd order GLCM feature "difference variance" (p = 0.007) significantly increased in patients experiencing CR. A similar trend, however, without statistical significance, could be observed in patients achieving PR after treatment. 2nd order GLCM feature "difference variance" proved to be a significant discriminator (p = 0.01) between patients with CR and PR (sensitivity 0.93, specificity 0.70) for a cut-off value of -0.28. In patients classified CR, both the mean serum protein and the beta-2 microglobulin decreased after treatment, whereas the serum albumin increased (p < 0.01). The same trend without significance could be observed in patients classified PR.

CONCLUSIONS

Changes in textural features applied on VNC bone marrow images in the pre- and posttreatment settings correlate well with myeloma-specific hematologic parameters and provide complementary information for the assessment of the late effects of treatment on the bone marrow.

7T bone perfusion imaging of the knee using arterial spin labeling MRI

PURPOSE

To evaluate the feasibility of arterial spin labeling (ASL) imaging of epiphyseal bone marrow in the distal femoral condyle of the knee at 7T MRI.

METHODS

The knees of 7 healthy volunteers were imaged with ASL using a 7T whole body MRI scanner and a 28-channel knee coil. ASL imaging used a flow-sensitive alternating inversion recovery method for labeling and a single-shot fast spin echo sequence for image readout. ASL imaging with a single oblique transverse slice was performed at 2 slice positions in the distal femoral condyle. Blood flow was measured in 2 regions of interest: the epiphyseal bone marrow and the overlying patellofemoral cartilage. To analyze perfusion SNR, 200 noise images were also acquired using the same ASL imaging protocol with RF pulses turned off.

RESULTS

Knee bone marrow perfusion imaging was successfully performed with all volunteers. The overall mean of blood flow in the knee bone marrow was 32.90 ± 2.41 mL/100 g/min, and the blood flow was higher at the more distal slice position. We observed significant B₀ and B 1 + inhomogeneities, which need to be addressed in the future to improve the quality of ASL imaging and increase the reliability of knee bone marrow perfusion measurements.

CONCLUSION

Bone marrow perfusion imaging of the distal femoral condyle is feasible using ASL at 7T. Further technical development is needed to improve the ASL method to overcome existing challenges.

Whole-body MRI, dynamic contrast-enhanced MRI, and diffusion-weighted imaging for the staging of multiple myeloma

Magnetic resonance imaging (MRI) is the most sensitive imaging technique for the detection of bone marrow infiltration, and has therefore recently been included in the new diagnostic myeloma criteria, as proposed by the International Myeloma Working Group. Nevertheless, conventional MRI only provides anatomical information and is therefore only of limited use in the response assessment of patients with multiple myeloma. The additional information from functional MRI techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced MRI, can improve the detection rate of bone marrow infiltration and the assessment of response. This can further enhance the sensitivity and specificity of MRI in the staging of multiple myeloma patients. This article provides an overview of the technical aspects of conventional and functional MRI techniques with practical recommendations. It reviews the diagnostic performance, prognostic value, and role in therapy assessment in multiple myeloma and its precursor stages.

MRI in multiple myeloma: a pictorial review of diagnostic and post-treatment findings

Magnetic resonance imaging (MRI) is increasingly being used in the diagnostic work-up of patients with multiple myeloma. Since 2014, MRI findings are included in the new diagnostic criteria proposed by the International Myeloma Working Group. Patients with smouldering myeloma presenting with more than one unequivocal focal lesion in the bone marrow on MRI are considered having symptomatic myeloma requiring treatment, regardless of the presence of lytic bone lesions. However, bone marrow evaluation with MRI offers more than only morphological information regarding the detection of focal lesions in patients with MM. The overall performance of MRI is enhanced by applying dynamic contrast-enhanced MRI and diffusion weighted imaging sequences, providing additional functional information on bone marrow vascularization and cellularity.

This pictorial review provides an overview of the most important imaging findings in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma, by performing a ‘total’ MRI investigation with implications for the diagnosis, staging and response assessment.

Main message

• Conventional MRI diagnoses multiple myeloma by assessing the infiltration pattern.

• Dynamic contrast-enhanced MRI diagnoses multiple myeloma by assessing vascularization and perfusion.

• Diffusion weighted imaging evaluates bone marrow composition and cellularity in multiple myeloma.

• Combined morphological and functional MRI provides optimal bone marrow assessment for staging.

• Combined morphological and functional MRI is of considerable value in treatment follow-up.

The diagnostic value of SE MRI and DWI of the spine in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma

OBJECTIVES

To evaluate DWI of the bone marrow in the differentiation of monoclonal gammopathy of undetermined significance (MGUS), smouldering myeloma (SMM) and multiple myeloma (MM).

METHODS

The retrospective study includes 64 patients with MGUS, 27 with SMM, 64 with new MM and 12 controls. Signal intensity (SI) of spinal SE-MRI and DWI (b0-1000) as well as apparent diffusion coefficients (ADC) were measured in the T10 and L3. Qualitative assessment of b-images was performed by one experienced radiologist.

RESULTS

ADC600 and ADC1000 are the best ADC values in differentiating patient groups (p < 0.030). SIT2, SIb1000 and ADC1000 are higher and SIT1 lower in L3 compared to T10 (p < 0.050). All quantitative parameters of L3 can differentiate significantly between MGUS and MM (p < 0.050) and between patients with percentage plasma cells (PC%) between 0-10 % compared to >50 % (p = 0.001). Only SIT2 for L3 can differentiate MGUS from SMM (p = 0.044) and PC%0-10 from PC%10-25 (p = 0.033). Qualitative interpretation of b1000 images allows differentiating MM patients from those with MGUS or SMM (p < 0.001).

CONCLUSIONS

Spinal SE-MRI can differentiate among MGUS, SMM, MM and control subjects. DWI based on the SI on b1000 images and ADC values is increased in MM compared to MGUS and SMM. Qualitative assessment of b-images can differentiate MM from MGUS or SMM.

KEY POINTS

• ADC values are higher in patients with MM compared to MGUS • DWI parameters change late in disease evolution • DWI is sensitive but not specific in diagnosing patients with MM • Qualitative DWI assessment is good in detecting myeloma patients.

Hematopoietic tumors and metastases involving bone

This review explores in depth the most common malignant process involving the bone, namely metastatic disease, as well as some of the more common proliferative forms of hematopoietic disease of bone marrow. These are commonly encountered pathologic processes that often have vague nonspecific symptoms. Imaging findings are frequently subtle on initial radiographs; however, advanced imaging techniques, including CT, MR, and positron emission tomography, allow for accurate diagnosis, staging, and follow-up in most cases.

Modern imaging techniques during therapy in patients with multiple myeloma

Imaging modalities used in the diagnosis of multiple myeloma have evolved and most of them are also suitable for either early or mid-term monitoring of response to novel antimyeloma therapy. This pictorial essay focuses on modern imaging techniques for diagnosis and follow-up of patients with multiple myeloma in order to highlight their individual strengths and limitations. Also, the impact of recently established modern pharmaceutical therapy, like anti-angiogenic medication, on the tumor is addressed.