Contrast Magnetic Resonance Imaging Study Research Articles

Delayed contrast and multiparametric MRI for treatment response assessment in brain metastases following stereotactic radiosurgery

Abstract Aims Following stereotactic radiosurgery (SRS), brain metastases can increase in size in up to a third of cases. Conventional magnetic resonance imaging (MRI) has a limited role to distinguish between tumour recurrence and SRS-induced changes, which can impact patient management. Delayed contrast MRI treatment response assessment maps (TRAM) use the principle of contrast clearance seen in other tumours, where high vascularity shows a rapid rise in contrast as well as rapid clearance, whereas areas of damaged or low vascularity show accumulation of contrast. We aimed to assess the ability of delayed contrast MRI and multiparametric MRI techniques of diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI) and MR spectroscopy (MRS) to distinguish between radiation-related effects and tumour tissue, as these techniques assess tissue physiological and metabolic information. Method A retrospective review was performed on 23 patients who had delayed contrast and multiparametric MRI between October 2018 to April 2020. Studies were restricted to cases with brain metastases enlarging post-SRS with uncertainty at the MDT meeting regarding progression or treatment-related change, impacting the patient’s management. MRI was performed at 3T including DWI, PWI, MRS with short and intermediate echo times, and 3D T1 MPRAGE at 3-5, 20-30 and 70-90 minutes after administration of intravenous contrast. Contrast clearance analysis was performed by selecting an enhancing region of interest (ROI), measuring signal intensities at the three different timepoints and taking apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) values from the ROI. Choline/Creatine values were calculated from a single-voxel (10 mm isotropic) encompassing the entire contrast-enhancing lesion. Outcome was established from MRI follow-up at 6 months, with a stable or responding lesion considered treatment-related changes and increase considered progression. Results Across 23 patients, 24 metastases were assessed. Two patients were excluded as appropriate follow-up was not available. Sites of primary tumours included breast (n=8), lung (n=6), melanoma (n=4), neuroendocrine tumour from the lung (n=2) and renal cell carcinoma (n=2). Mean age was 56 years and 50% were female. In this cohort, 59% (n=13) were classified as having radiation-related changes on follow-up. Delayed MRI contrast clearance between the 3-5 and 70-90 minute imaging was significantly higher in cases of progression (23.6% vs. 2.5% decrease, p<0.05), as were the rCBV and Cho/Cr ratio (rCBV 3.1 vs. 1.5 and Cho/Cr ratio 2.3 vs. 1.4, p<0.05). Accuracy, sensitivity and specificity of using TRAM alone (contrast clearance decrease of >0%) for progression was 63%/100%/38%, PWI alone (rCBV cut-off 2.0) yielded results of 77%/75%/79% and for both Cho/Cr ratio alone (cut-off 1.8) and combined with TRAM, it was 90%/88%/92%. Neuroradiologist assessment of all techniques was 95%/100%/92%. Conclusion This study shows the effectiveness of delayed contrast and multiparametric MRI for treatment response assessment in patients with brain metastases treated by SRS in clinical practice. Although a delayed contrast MRI study is a very sensitive tool for detecting tumour progression, it lacks specificity. The accuracy of differentiating between tumour and treatment-related effects increases when delayed contrast MRI is used in combination with other advanced techniques such as MRS. By combining all these techniques, neuroradiologists had the highest accuracy, sensitivity and specificity for detecting progression in post-SRS brain metastases.

Is cerebral spinal fluid flow associated with body mass index and head circumference in healthy children? A phase contrast magnetic resonance imaging study

BackgroundThe aim of this study was to investigate the relationship between age, gender, body mass index (BMI), and head circumference (HC) and cerebral spinal fluid (CSF) flow dynamics in the pediatric population. The prospective study included a total of 137 participants, 75 boys and 62 girls, ranging in age from 2 to 204 months. Quantitative evaluation of CSF flow was made by using phase contrast magnetic resonance imaging (PC-MRI) in the axial plane at the level of the aqueductus cerebri. Flow dynamics were recorded as peak and mean velocity (cm/s); cranial, caudal, and net volume (ml); and aqueductus cerebri area (mm2). Correlation between baseline descriptive parameters, including age, gender, BMI, and HC, and the aforementioned CSF flow dynamics were investigated.ResultsThe net volume was significantly lower in girls (p = 0.002). There was no association between age and aqueduct area, mean velocity, and cranial volume. The peak velocity was remarkably higher in children (p = 0.03), whereas cranial and net volume were found to be lower in infants (p = 0.04 and p = 0.03, respectively). Notably, cases with HC below normal values had lower cranial, caudal, and net volume and aqueductus cerebri area (p = 0.01, p = 0.03, p = 0.03, and p = 0.04, respectively). There was no association between BMI and indicators of CSF flow dynamics in PC-MRI.ConclusionBMI and HC may be associated with CSF flow dynamics in children. A smaller HC is accompanied by a lower forward flow volume, reverse flow volume, net volume, and aqueductal diameter. These points should be remembered during the design of further trials on determinants of CSF flow in children.

ICP curve morphology and intracranial flow-volume changes: a simultaneous ICP and cine phase contrast MRI study in humans

BackgroundThe intracranial pressure (ICP) curve with its different peaks has been extensively studied, but the exact physiological mechanisms behind its morphology are still not fully understood. Both intracranial volume change (ΔICV) and transmission of the arterial blood pressure have been proposed to shape the ICP curve. This study tested the hypothesis that the ICP curve correlates to intracranial volume changes.MethodsCine phase contrast magnetic resonance imaging (MRI) examinations were performed in neuro-intensive care patients with simultaneous ICP monitoring. The MRI was set to examine cerebral arterial inflow and venous cerebral outflow as well as flow of cerebrospinal fluid over the foramen magnum. The difference in total flow into and out from the cranial cavity (Flowtot) over time provides the ΔICV. The ICP curve was compared to the Flowtot and the ΔICV. Correlations were calculated through linear and logarithmic regression. Student’s t test was used to test the null hypothesis between paired samples.ResultsExcluding the initial ICP wave, P1, the mean R2 for the correlation between the ΔICV and the ICP was 0.75 for the exponential expression, which had a higher correlation than the linear (p = 0.005). The first ICP peaks correlated to the initial peaks of Flowtot with a mean R2 = 0.88.ConclusionThe first part, or the P1, of the ICP curve seems to be created by the first rapid net inflow seen in Flowtot while the rest of the ICP curve seem to correlate to the ΔICV.

Detailed magnetic resonance imaging features of a case series of primary gliosarcoma.

Objective We aimed to characterise the magnetic resonance imaging (MRI) features of a case series of primary gliosarcoma, with the inclusion of diffusion-weighted imaging and perfusion imaging with dynamic susceptibility contrast MRI. Materials and methods We conducted a retrospective study of cases of primary gliosarcoma from the Pathology Department database from January 2006 to December 2014. Clinical and demographic data were obtained. Two neuroradiologists, blinded to diagnosis, assessed tumour location, signal intensity in T1 and T2-weighted images, pattern of enhancement, diffusion-weighted imaging and dynamic susceptibility contrast MRI studies on preoperative MRI. Results Seventeen patients with primary gliosarcomas had preoperative MRI study: seven men and 10 women, with a mean age of 59 years (range 27-74). All lesions were well demarcated, supratentorial and solitary (frontal n = 5, temporal n = 4, parietal n = 3); 13 tumours abutted the dural surface (8/13 with dural enhancement); T1 and T2-weighted imaging patterns were heterogeneous and the majority of lesions (12/17) showed a rim-like enhancement pattern with focal nodularities/irregular thickness. Restricted diffusion (mean apparent diffusion coefficient values 0.64 × 10-3 mm2/s) in the more solid/thick components was present in eight out of 11 patients with diffusion-weighted imaging study. Dynamic susceptibility contrast MRI study ( n = 8) consistently showed hyperperfusion in non-necrotic/cystic components on relative cerebral volume maps. Conclusions The main distinguishing features of primary gliosarcoma are supratentorial and peripheral location, well-defined boundaries and a rim-like pattern of enhancement with an irregular thick wall. Diffusion-weighted imaging and relative cerebral volume map analysis paralleled primary gliosarcoma with high-grade gliomas, thus proving helpful in differential diagnosis.

Changes in systemic and pulmonary blood flow distribution in normal adult volunteers in response to posture and exercise: a phase contrast magnetic resonance imaging study

Hemodynamics are usually evaluated in the supine position at rest. This is only a snapshot of an individual's daily activities. This study describes circulatory adaptation, as assessed by magnetic resonance imaging, to changes in position and exercise. Phase contrast magnetic resonance imaging of blood flow within systemic and pulmonary arteries and veins was performed in 24 healthy volunteers at rest in the prone and supine position and with bicycle exercise in the supine position. No change was seen in systemic blood flow when moving from prone to supine. Exercise resulted in an increased percentage of cardiac output towards the lower body. Changes in position resulted in a redistribution of blood flow within the left lung--supine positioning resulted in decreased blood flow to the left lower pulmonary vein. With exercise, both the right and left lower lobes received increased blood flow, while the upper lobes received less.

Is the Transport of a Gadolinium-Based Contrast Agent Decreased in a Degenerated or Aged Disc? A Post Contrast MRI Study

A post contrast magnetic resonance imaging study has been performed in a wide population of low back pain patients to investigate which radiological and phenotypic characteristics influence the penetration of the contrast agent in lumbar discs in vivo. 37 patients affected by different pathologies (disc herniation, spondylolisthesis, foraminal stenosis, central canal stenosis) were enrolled in the study. The selected population included 26 male and 11 female subjects, with a mean age of 42.4±9.3 years (range 18–60). Magnetic resonance images of the lumbar spine were obtained with a 1.5 T scanner (Avanto, Siemens, Erlangen, Germany) with a phased-array back coil. A paramagnetic non–ionic contrast agent was injected with a dose of 0.4 ml/kg. T1-weighted magnetic resonance images were subsequently acquired at 5 time points, 5 and 10 minutes, 2, 4 and 6 hours after injection. Endplates presented clear enhancement already 5 minutes after injection, and showed an increase in the next 2 hours followed by a decrease. At 5 and 10 minutes, virtually no contrast medium was present inside the intervertebral disc; afterwards, enhancement significantly increased. Highly degenerated discs showed higher enhancement in comparison with low and medium degenerated discs. Discs classified as Pfirrmann 5 showed a statistically significant higher enhancement than Pfirrmann 1, 2 and 3 at all time points but the first one, possibly due to vascularization. Disc height collapse and Modic changes significantly increased enhancement. Presence of endplate defects did not show any significant influence on post contrast enhancement, but the lack of a clear classification of endplate defects as seen on magnetic resonance scans may be shadowing some effects. In conclusion, disc height, high level of degeneration and presence of Modic changes are factors which increase post contrast enhancement in the intervertebral disc. The effect of age could not be demonstrated.

1135: Development of a Three-Dimensional Anisotropic Pelvic Lymph Node Clinical Target Volume and Planning Target Volume Using Magnetic Resonance Lymphadenography With Ferumoxtran-10

1135: Development of a Three-Dimensional Anisotropic Pelvic Lymph Node Clinical Target Volume and Planning Target Volume Using Magnetic Resonance Lymphadenography With Ferumoxtran-10

Magnetic Resonance Lymphography with Ferumoxtran-10 for Pelvic Lymph Node Target Delineation in Bladder and Prostate Cancer

Purpose/Objective: To determine the utility of Magnetic Resonance Imaging (MRI) with an ultra-small superparamagnetic iron oxide that delineates phagocytotic activity within lymph nodes as a means of lymph node target definition and to examine the patterns of lymph node metastases in prostate and bladder cancer to generate a nodal clinical target volume comprised of the nodal basins at risk of tumor spread. Materials/Methods: A single center trial was undertaken in 40 patients with histologically confirmed prostate (32) or bladder cancer (8). All patients underwent pre- and post- contrast MRI studies over two consecutive days. Axial images were obtained at 3 mm intervals through the pelvis. Ferumoxtran-10 (Combidex®: Advanced Magnetics, Inc, Cambridge, MA) was administered at 2.6 mg Fe/kg on the first day immediately after the initial MRI. The pelvic vasculature and lymph nodes were delineated from the origin of the inferior mesenteric artery to the ischial tuberosities using 3D modeling and image processing software (3D-DOCTOR®: Able Software Corp., Lexington, MA). Lymph node frequency and location relative to the adjacent vascular segments was analyzed. Nodes were ascertained to have metastases using previously demonstrated criteria and with clinicopathologic correlation in those patients undergoing pelvic lymph node dissection (Harisinghani et al. NEJM 2003;348:2491-9). The prostate cancer patients were treated with radiotherapy. However, patients with bladder cancer underwent radical cystectomy and pelvic lymph node dissection, allowing surgicopathologic correlation of the imaging results. Results: 40 patients were enrolled (see Table 1). In the patients with prostate cancer, 39 malignant nodes were identified. Metastases were situated in the following locations or vascular segments: obturator fossa (7); internal iliac (3); external iliac (11); common iliac (5); aortic/aortocaval (3); pararectal (6); and sacral (4). The median number of nodes excised at the time of cystectomy for those patients with bladder cancer was 29 (range 21 to 47). Pathologically, metastases were identified in the following locations or vascular segments: perivesicle (1); internal iliac (8); external iliac (6); common iliac (2); aortic/aortocaval (3); and pararectal (2). On post-contrast MRI imaging, a median of 27 (range 18 to 39) nodes was identified for both bladder and prostate cancer patients within the region occupied by the para-vesical, intercalating, para-rectal, pelvic sidewall, external iliac, common iliac, and pre-sacral lymph node basins. The maximum distance of these lymph nodes from the closest vessel was between 2.5 and 30 mm, with a mean distance of 7.5 mm.Table 1Patient Characteristics Conclusions: The use of MRI lymphography with ferumoxtran-10 provides an objective description of pertinent lymph node locations in a three-dimensional projection for pelvic IMRT and improves the precision of radiation treatment delivery. A uniform radial margin of expansion around the major pelvic vessels fails to adequately encompass all of the parietal and visceral lymph nodes at risk. Ferumoxtran-10 may be useful in the context of IMRT treatment planning as a means of identifying lymph nodes at risk of harbouring occult metastatic disease that should be included in the nodal CTV, and as a means of lowering the threshold for the detection of lymph node metastases that might be treated to a higher dose.