Inter-observer agreement of baseline whole body MRI in multiple myeloma.

BACKGROUND: Whole body magnetic resonance imaging (MRI) is now incorporated into international guidance for imaging patients with multiple myeloma. The aim of this study was to investigate inter-observer agreement of triple reported baseline whole-body MRI in myeloma and highlight potential pitfalls. METHODS: Fifty-seven patients with symptomatic myeloma at first presentation or relapse and planned for autologous stem cell transplant were included. All patients completed baseline whole body MRI within 2 weeks prior to starting treatment. Each scan was reported independently by 3 radiologists using a defined scoring system. Differences in observer scores were compared using analysis of variance (ANOVA) and inter-observer agreement assessed using intra class correlation coefficient (ICC). RESULTS: There was no significant difference in mean observer scores for whole skeleton and ICC demonstrated excellent inter-observer agreement at 0.91. ICC varied between skeletal regions with spine, pelvis and ribs showing good inter-observer agreement, whereas skull and long bones were moderate. Scans with variation in observer scores were re-examined and cause of discrepancies identified. This information was used to describe potential anatomical pitfalls in reporting . CONCLUSION: Whole-body MRI has excellent inter-observer agreement in reporting symptomatic myeloma at baseline. Inter-observer agreement varied between skeletal regions highlighting specific areas of difficulty.

Imaging in clinical trials: a patient-led questionnaire study to assess impact of imaging regimes on patient participation.

BACKGROUND: Cancer trials often incorporate intensive imaging with Magnetic Resonance Imaging (MRI) and Positron Emission Tomography with Computerised Tomography (PET/CT), which can be physically and mentally exhausting for patients. This questionnaire study aimed to determine the aspects of imaging that affect a patient's decision to participate in clinical trials in order to inform the design of future trials that utilise imaging. This should achieve greater patient compliance and improve the patient experience. METHOD: A detailed questionnaire assessing patient expectation and acceptability of imaging within clinical trials was developed in collaboration with two patient representatives. The questionnaire addressed the influence of scan type, length, frequency, scheduling, invasiveness and staff support on acceptability of imaging. It was applied to three patient groups. Group 1 consisted of patients newly recruited to studies with imaging, Group 2 consisted of previous participants in studies with imaging and Group 3 consisted of patients having imaging for clinical care. RESULTS: One hundred ninety six patients completed the questionnaires (Group 1:47; Group 2: 50 and Group 3: 99). The use of ionising radiation and number of scans required were identified as negative influences on decision to participate by 25% of Group 3 but only by 6% of Groups 1 and 2. Scan duration >30mins was perceived as a negative factor for decision to participate by all Groups (12-22%). Good communication provided by researchers in terms of discussing the study before and after reading study materials was a key factor in influencing decision to participate (> 50% in Groups 1 and 2 and > 20% in Group 3). CONCLUSION: Factors relating to imaging procedures within clinical trials that affect participation have been identified with communication around study materials as the key determinant. These data will be used to influence the development of future research protocols. Modification of imaging requirements within clinical trials will improve patient tolerance and acceptability and is likely to raise recruitment.

A novel approach to evaluate spatial resolution of MRI clinical images for optimization and standardization of breast screening protocols.

PURPOSE: Stringent quality assurance is required in MRI breast screening to ensure that different scanners and imaging protocols reach similar diagnostic performance. The authors propose a methodology, based on power spectrum analysis (PSA), to evaluate spatial resolution in clinical images. To demonstrate this approach, the authors have retrospectively compared two MRI sequences commonly employed in breast screening. METHODS: In a novel approach to PSA, spatial frequency response curves (SFRCs) were extracted from the images. The SFRC characterizes spatial resolution describing the spatial frequency content of an image over a range of frequencies. Verification of the SFRCs was performed on MRI images of Eurospin agarose gel tubes acquired with different resolution settings. SFRCs of volunteer and patient images obtained with two clinical MRI sequences were then compared. The two sequences differed primarily in k-space coverage pattern, which was either radial (RAD) or linear (LIN). RESULTS: The computed SFRCs were able to demonstrate the differences between RAD and LIN sequences in relatively small groups of subjects. The curves showed a similar pattern of decay in both volunteer and patient images, indicating that the spatial frequency response is mainly determined by the imaging protocol and not by intersubject anatomical differences. The LIN protocol produced images with increased sharpness; this was reflected in the corresponding SFRCs, which showed a higher content of spatial frequencies associated with image details. CONCLUSIONS: The SFRC can provide an objective assessment of the presence of spatial details in the image and represent a useful quality assurance tool in the evaluation of different breast screening protocols. With a reference image, a comparative analysis of the SFRCs could ensure that equivalent image quality is achieved across different scanners and sites.

Investigating the influence of flip angle and k-space sampling on dynamic contrast-enhanced MRI breast examinations.

RATIONALE AND OBJECTIVES: To retrospectively investigate the effect of flip angle (FA) and k-space sampling on the performance of dynamic contrast-enhanced (DCE-) magnetic resonance imaging (MRI) breast sequences. MATERIALS AND METHODS: Five DCE-MRI breast sequences were evaluated (10°, 14°, and 18° FAs; radial or linear k-space sampling), with 7-10 patients in each group (n = 45). All sequences were compliant with current technical breast screening guidelines. Contrast agent (CA) uptake curves were constructed from the right mammary artery for each examination. Maximum relative enhancement, E(max), and time-to-peak enhancement, T(max), were measured and compared between protocols (analysis of variance and Mann-Whitney). For each sequence, calculated values of maximum relative enhancement, E(calc), were derived from the Bloch equations and compared to E(max). Fat suppression performance (residual bright fat and chemical shift artifact) was rated for each examination and compared between sequences (Fisher exact tests). RESULTS: Significant differences were identified between DCE-MRI sequences. E(max) increased significantly at higher FAs and with linear k-space sampling (P < .0001; P = .001). Radial protocols exhibited greater T(max) than linear protocols at FAs of both 14° (P = .025) and 18° (P < .0001), suggesting artificially flattened uptake curves. Good correlation was observed between E(calc) and E(max) (r = 0.86). Fat suppression failure was more pronounced at an FA of 18° (P = .008). CONCLUSIONS: This retrospective approach is validated as a tool to compare and optimize breast DCE-MRI sequences. Alterations in FA and k-space sampling result in significant differences in CA uptake curve shape which could potentially affect diagnostic interpretation. These results emphasize the need for careful parameter selection and greater standardization of breast DCE-MRI sequences.

The value of magnetic resonance imaging in target volume delineation of base of tongue tumours--a study using flexible surface coils.

INTRODUCTION: Magnetic resonance imaging (MRI) provides superior diagnostic accuracy over computed tomography (CT) in oropharyngeal tumours. Precise delineation of the gross tumour volume (GTV) is mandatory in radiotherapy planning when a GTV boost is required. CT volume definition in this regard is poor. We studied the feasibility of using flexible surface (flex-L) coils to obtain MR images for MR-CT fusion to assess the benefit of MRI over CT alone in planning base of tongue tumours. METHODS: Eight patients underwent CT and MRI radiotherapy planning scans with an immobilisation device. Distortion-corrected T1-weighted post-contrast MR scans were fused to contrast-enhanced planning CT scans. GTV, clinical target and planning target volumes (CTV, PTV) and organs at risk (OAR) were delineated on CT, then on MRI with blinding to the CT images. The volumetric and spatial differences between MRI and CT volumes for GTV, CTV, PTV and OAR were compared. MR image distortions due to field inhomogeneity and non-linear gradients were corrected and the need for such correction was evaluated. RESULTS: The mean primary GTV was larger on MRI (22.2 vs. 9.5 cm(3), p=0.05) than CT. The mean primary and nodal GTV (i.e. BOT and macroscopic nodes) was significantly larger on MRI (27.2 vs. 14.4 cm(3), p=0.05). The volume overlap index (VOI) between MRI and CT for the primary was 0.34 suggesting that MRI depicts parts of the primary tumour not detected by CT. There was no significant difference in volume delineation between MR and CT for CTV, PTV, nodal CTV and nodal PTV. MRI volumes for brainstem and spinal cord were significantly smaller due to improved organ definition (p=0.002). Susceptibility and gradient-related distortions were not found to be clinically significant. CONCLUSION: MRI improves the definition of tongue base tumours and neurological structures. The use of MRI is recommended for GTV dose-escalation techniques to provide precise depiction of GTV and improved sparing of spinal cord and brainstem.