Signal Intensities In Regions Of Interest Research Articles

Whole Body (WB) MRI in Newly Diagnosed Multiple Myeloma (MM): Fat Fraction Changes at 8 Weeks Predict Response to Induction with Bortezomib Regimens

Background. Recent advances in MM therapy create a need for multi-modality response assessments, in order to optimise patient outcomes. Radiological tools can assess the entire skeleton, with the potential to depict heterogeneity of response and help target biopsy of resistant lesions. MRI-based assessment of focal lesions (FL) has been incorporated into the definition of symptomatic MM, providing the rationale for exploring MRI-based response assessment biomarkers. Diffusion weighted imaging derived apparent diffusion coefficient (ADC) has been studied, but standardisation of ADC values across MRI scanners is challenging, limiting generalisability. Fat fraction (FF), also evaluable by MRI, may be a more reliable parameter that could be expected to increase following response to therapy.Methods. This study aimed to evaluate changes in FF in FLs of newly diagnosed MM patients by whole body MRI (WB-MRI) prior to treatment (Pre) and after 8 weeks (8W). WB-MRI was performed on a 3.0 T scanner. Whole-body T2 weighted imaging and axial DWI MRI were supplemented by pre- and post-contrast coronal 2-point mDixon imaging for evaluation of FF. mDixon images were reconstructed as fat only and water only studies. For each patient, up to 20 FLs were localised for analysis by 2 radiologists in consensus, who prospectively scored (score 1-5, 1=highly unlikely, 5=highly likely) involvement of each of 10 anatomical regions. FLs > 5mm with score 4 or 5 were selected for quantitative analysis. A matched region of interest (ROI) was contoured for each FL on water only and fat only mDixon images as well as DWI images. FF was derived from ROI signal intensity (SI) by: SIfat/SIwater+SIfat. Estimated tumour volume (eTV) and DWI's ADC of each FL was also calculated. Difference in FF, eTV and ADC between Pre and 8W studies was assessed by Wilcoxon matched pairs test. Disease response was assessed by IMWG criteria. FF, eTV and ADC receiver operating characteristic (ROC) area under the curve (AUC) analysis was conducted for prediction of non-responders at the end of induction.Results. 21 patients (13 male), median age 52 (range 36-69) were enrolled. Patients had IgG (13), IgA (4) or LC MM (4), and 7 had adverse FISH results [t(4;14), t(14;16), 1q+ or del(17p)] with median ISS II (ISS I (8), II (10), III (3)). Each received a bortezomib induction regimen (16 PAD, 3 CVD, 2 VTD) for 4-6 cycles. A total of 325 FLs were analysed in the entire cohort, with a median of 20 (IQR 10-20, mean 15.5) FLs per patient. At baseline (Pre), median or mean eTV, FF or ADC was found to be independent of ISS stage or genetic risk. Fifteen patients (71%) had an overall response (³PR) to induction therapy. Response was not found to correlate with median FL count, baseline (Pre) FF, eTV or ADC. However, at 8W a significant increase in FF was observed in responders (from median 0.25 to 0.47 a.u. at 8W, p<0.0001), but no change was seen in non-responders (p=0.22); eTV significantly decreased in both groups (from median 0.22 to 0.11 and 0.31 to 0.21 for responders and non-responders, respectively p<0.01 and p=0.02). ADC increased in responders (from median 0.79 to 1.46 x 10-3 mm2 /s at 8W, p<0.01) but was not significantly changed in the non-responder group (p=0.2).One responding patient had only 1 FL and was excluded from per patient analysis. Of the remaining 14 responders, 13 had a significant increase in FF (p<0.01-0.02) and decrease in eTV (p<0.01-0.02), the 14th patient had only 4 FLs, with a non-significant increase in FF and no change in eTV; 8/14 demonstrated an increase (p<0.01-0.03) and 1/14 (p=0.01) a decrease in ADC. The remaining patients (5/14) had no significant changes in ADC (p=0.24-0.6).All patients who failed to achieve at least PR (6) had no changes in FF (p values 0.10-0.80); 4/6 had no change in ADC (p=0.10-0.84) whilst 2/6 showed a significant increase (p=0.02, 0.03). All non-responders (6/6) had a significant decrease in eTV (p<0.01-0.02). Percentage changes in FF, eTV and ADC at 8W had an ROC-AUC of 1.0, 0.48 and 0.72 for prediction of response at 6 months.Conclusions. WB-MRI derived FF change of FLs at 8 weeks following induction therapy differentiates responders from non-responders in newly diagnosed MM patients. This may have utility to act as both an early response and predictive imaging biomarker. [Display omitted] [Display omitted] DisclosuresYong:Takeda: Honoraria; Amgen: Honoraria; BMS: Honoraria; Novartis: Consultancy; Janssen: Honoraria; Autolous: Consultancy. Popat:Janssen: Honoraria.

Multiphase Arterial Spin Labeling Assessment of Cerebral Perfusion Changes Associated with Middle Cerebral Artery Stenosis

To assess the sensitivity and utility of multiphase pulsed arterial spin labeling (PASL) in detecting dynamic changes of cerebral perfusion in the presence of a middle cerebral artery (MCA) severe stenosis. Seventeen patients with severe stenoses in unilateral M1 segment of MCA were involved in this study. All patients underwent multiphase PASL imaging. Bilateral basal ganglia were drawn by hand as regions of interest (ROIs) on eight-phase images of each patient. The signal intensities of ROIs were measured and the time-intensity curves (TICs) were acquired through postprocessing on a magnetic resonance workstation. Whether there was a significant difference in the peak signal intensities of ROIs between the narrowed and normal sides was determined by the paired samples t test. Three types of TICs were observed: eight cases with platform type, five cases with two-peak type, and four cases with single-peak type. There was a significant difference in the peak signal intensities of ROIs between the narrowed and normal sides. Different types of TICs represent different cerebral hemodynamic changes. Multiphase PASL can sensitively detect the dynamic characteristics of cerebral perfusion and provide important dynamic perfusion information for clinical treatment of arterial stenosis.

Bone metastases from prostate, breast and multiple myeloma: differences in lesion conspicuity at short-tau inversion recovery and diffusion-weighted MRI

The objective of this study was to compare the relative conspicuity of bone metastases on short-tau inversion recovery (STIR) and diffusion-weighted MRI (DWI) whole-body MR sequences for breast, prostate and myeloma malignancies. 44 whole-body MRI scans were reviewed retrospectively (coronal T(1) weighted, STIR and DWI with b=800). On each scan, up to four of the largest bone lesions were identified on T(1) weighting, and the region of interest signal intensity was measured on STIR and DWI, as well as the background signal intensity. The mean lesion signal to background ratio was calculated for each patient and then for each malignancy group. In prostate cancer patients, the DWI signal/background ratio was greater than that of STIR in 22 out of 24 patients (mean DWI lesion/background ratio 3.91, mean STIR lesion/background ratio 2.31; p=0.0001). In multiple myeloma, the DWI ratio was higher in 6/7 patients (DWI group mean ratio 7.59, STIR group mean ratio 3.7; p=0.0366). In 13 breast cancer patients, mean STIR and DWI signal/background were similar (DWI group mean ratio 4.13, group mean STIR ratio 4.26; p=0.8587). Bone lesion conspicuity measured by lesion/background signal intensity was higher on DWI b=800 than on STIR in patients with prostate cancer and multiple myeloma. DWI should be used in whole-body MR oncology protocols in these conditions to maximise lesion detection.

Changes in Tumor Blood Flow as Measured by Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) May Predict Activity of Single Agent Bevacizumab in Recurrent Epithelial Ovarian (EOC) and Primary Peritoneal Cancer (PPC) Patients: An exploratory analysis of a Gynecologic Oncology Group Phase II study

ObjectiveTo explore feasibility of measuring tumor blood flow as marker for antiangiogenic activity using DCE-MRI (Dynamic Contrast-Enhanced Magnetic Resonance Imaging) in women with recurrent EOC/PPC treated with bevacizumab. MethodsIn a phase II study, 62 patients with recurrent/persistent EOC/PPC were treated with bevacizumab (15mg/kg IV q21days) until disease progression. DCE-MRI was performed pre-cycle 1 and 4 of bevacizumab. Images were analyzed retrospectively by a single experienced blinded radiologist. Tumor and muscle contrast enhancement was measured by region of interest signal intensity within the same DCE-MRI images. Flow rates were obtained with concentration of dye as a function of time. Relative blood flow (RBF) was calculated as a ratio of average blood flow into tumor to muscle tissue. Associations between RBF and characteristics/outcomes were explored. ResultsSixty-two patients were eligible for study. Unfortunately, only 14 (23%) patients had imaging data available for analysis at baseline and 13 of those same patients (21%) had imaging data available for analysis pre-cycle 4. The RBF distribution was similar from pre-cycle 1 to 4. RBF remained stable for the majority of the cases (median change -0.21). Baseline RBF was not significantly associated with being progression-free at 6months, microvessel density, 17month overall survival, tumor response, or platinum sensitivity. However, increases in blood flow rates were associated with likelihood to be progression-free at 6months. ConclusionFunctional imaging of tumor blood flow is a potential research endpoint that may be explored further. Consideration should be given to timing of endpoint and standardizing the technique.

The usefulness of delayed contrast-enhanced cardiovascular magnetic resonance imaging in differentiating cardiac tumors from thrombi in stroke patients

The objectives of this study were to evaluate the diagnostic value of delayed-enhancement cardiovascular magnetic resonance (DE-CMR) imaging in differentiating cardiac tumors from thrombi in patients with suspected cardio-embolic stroke. Two radiologists blinded to the study protocol retrospectively evaluated MR images of 22 patients (12 men and 10 women; mean age 59.2 years) that had recently experienced a stroke and undergone CMR. Six cardiac tumors and 16 thrombi were confirmed on surgery or follow-up examinations. On DE-CMR, a tumor was defined as an intracardiac mass showing post-contrast enhancement, and a thrombus was defined as an intracardiac mass showing black signal intensity (SI) without post-contrast enhancement. The mean SI in regions of interest in the normal myocardium and cardiac mass were measured using cine-CMR and DE-CMR. Visual assessment of enhancement characteristics of cardiac masses on DE-CMR could accurately differentiate cardiac tumors from thrombi in all cases. On cine-CMR, the mean SI ratios for tumors and thrombi were 1.45 ± 0.45 (range, 1.12-2.16) and 1.39 ± 0.33 (range, 0.87-2.09), respectively (P = 0.745). On DE-CMR, the mean SI ratios for tumors and thrombi were 5.65 ± 2.96 (range, 2.98-9.92) and 1.06 ± 0.43 (range, 0.67-1.95), respectively (P < 0.001). DE-CMR is a non-invasive modality for detecting intra-cardiac mass can differentiate tumors from thrombi in cardio-embolic stroke patients.

3 Tesla Delayed Contrast Magnetic Resonance Imaging Evaluation of Ménière's Disease

To determine whether 3 Tesla (T) magnetic resonance imaging (MRI) with delayed contrast imaging has sufficient anatomic resolution to image the intracochlear fluid spaces (i.e., the scala tympani, scala media, and scala vestibuli) of the inner ear and identify endolymphatic hydrops in vivo. Four normal subjects underwent 3T MRI scanning after the administration of gadodiamide intravenous (IV) contrast. MRI region of interest signal intensity was used to determine the diffusion of gadodiamide into the perilymphatic fluid spaces over time. Seven subjects with unilateral Ménière's disease underwent 3T MRI 4 hours after administration of gadodiamide IV contrast agent. All four normal subjects demonstrated perilymphatic enhancement by 4 hours postinjection. Loss of definition of the membranous cochlea was noted in five of the seven subjects with Ménière's disease. Precise definition of the scala media could not be achieved with this imaging protocol. Delayed contrast imaging of the inner ear with 3T MRI revealed in vivo changes of the membranous labyrinth consistent with unilateral Ménière's disease.

Trabecular structure: preliminary application of MR interferometry.

A new approach to probe the structure of trabecular bone in the vertebral bodies in humans was evaluated, and preliminary data are presented. The proposed method is based on the hypothesis that the presence of two physical phases--bone and bone marrow--causes a magnetic field distribution across the imaging voxel. The resulting spread in resonance frequency produces line broadening, which is measured as the decay rate of the region of interest signal intensity that has the properties of an interferogram. The interferogram is the result of two principal chemically shifted components of bone marrow--fat and water--getting in and out of phase with one another while being attenuated by T2* processes from the magnetic field distribution within the measuring volume. The time constant for the decay (T2*) can then be obtained by means of curve-fitting techniques. T2* in healthy persons is found to increase slightly with age. However, patients with osteoporosis (low bone mineral density and/or spine compression fractures) have significantly prolonged T2* values, which are interpreted as arising from an increase in the intertrabecular space.