Evaluation of renal quantitative T2* changes on MRI following administration of ferumoxytol as a T2* contrast agent

Sandeep S Hedgire,1 Shaunagh McDermott,1 Gregory R Wojtkiewicz,1 Seyed Mahdi Abtahi,1 Mukesh Harisinghani,1 Jason L Gaglia21Center for Systems Biology, Massachusetts General Hospital, Richard B Simches Research Center, 2Joslin Diabetes Center, Boston, MA, USAPurpose: To evaluate the time-dependent changes in regional quantitative T2* maps of the kidney following intravenous administration of ferumoxytol.Materials and methods: Twenty-four individuals with normal kidney function underwent T2*-weighted MRI of the kidney before, immediately after, and 48 hours after intravenous administration of ferumoxytol at a dose of 4 mg/kg (group A, n=12) or 6 mg/kg (group B, n=12). T2* values were statistically analyzed using two-tailed paired t-tests.Results: In group A, the percentage changes from baseline to immediate post and baseline to 48 hours were 85.3% and 64.2% for the cortex and 90.8% and 64.6% for the medulla, respectively. In group B, the percentage changes from baseline to immediate post and baseline to 48 hours were 85.2% and 73.4% for the cortex and 94.5% and 74% for the medulla, respectively. This difference was significant for both groups (P<0.0001).Conclusion: There is significant and differential uptake of ferumoxytol in the cortex and medulla of physiologically normal kidneys. This differential uptake may offer the ability to interrogate renal cortex and medulla with possible clinical applications in medical renal disease and transplant organ assessment. We propose an organ of interest based dose titration of ferumoxytol to better differentiate circulating from intracellular ferumoxytol particles.Keywords: USPIO, ferumoxytol, renal MRI, T2* weighted imagin

Randomized prospective comparative study of adductor canal block versus periarticular infiltration on early functional outcome after unilateral total knee arthroplasty

Background: Total knee arthroplasty (TKA) is associated with significant post-operative pain. Effective pain relief is essential for early post-operative rehabilitation. Periarticular infiltration (PAI) and Adductor canal block (ACB) have become popular modes of pain management after TKA. Our aim is to compare their efficacy and impact on early functional outcome in patients undergoing TKA. Methods: A single-blind randomised controlled trial, 100 patients undergoing unilateral primary TKA for symptomatic OA were allocated to either of the two groups (50 in each arm). Postoperative ultrasound guided single shot of ACB (Group A) or intra operative PAI (Group B). All patients underwent TKA without patella resurfacing under spinal anaesthesia. Pre-operative work up, surgical technique, post-operative management were standardised for all the patients. Patients were assessed for pain using VAS (Visual analogue scale) at 6, 12, 24 hrs after surgery, haemoglobin level preoperatively and post operatively on day 1 to calculate blood loss, hospital stay, tourniquet time (TT), operative time (OT) and post-operative complications by an independent observer blinded to the group allocation. Results: Patients were matched for age, gender, ASA grade and Deformity. VAS (scale 0-10) between PAI & ACB at 6, 12 & 24 hours were significantly different (p<0.05) with higher score seen in the patients with ACB at all time points. TT and OT were significantly longer in the PAI than ACB. No significant difference in the hospital stay observed. No complications occurred during the study. Conclusion: PAI achieves better pain control as compared to ACB in patients undergoing unilateral TKA

Enhanced primary tumor delineation in pancreatic adenocarcinoma using ultrasmall super paramagnetic iron oxide nanoparticle-ferumoxytol: an initial experience with histopathologic correlation

Sandeep S Hedgire,1 Mari Mino-Kenudson,2 Azadeh Elmi,1 Sarah Thayer,3 Carlos Fernandez-del Castillo,3 Mukesh G Harisinghani11Department of Abdominal Imaging and Intervention, 2Department of Pathology, 3Department of Surgery, Massachusetts General Hospital, Boston, MA, USAPurpose: To evaluate the role of ferumoxytol-enhanced magnetic resonance imaging (MRI) in delineating primary pancreatic tumors in patients undergoing preoperative neoadjuvant therapy.Materials and methods: Eight patients with pancreatic adenocarcinoma were enrolled in this study, and underwent MRI scans at baseline, immediate post, and at the 48 hour time point after ferumoxytol injection with quantitative T2* sequences. The patients were categorized into two groups; group A received preoperative neoadjuvant therapy and group B did not. The T2* of the primary pancreatic tumor and adjacent parenchyma was recorded at baseline and the 48 hour time point. After surgery, the primary tumors were assessed histopathologically for fibrosis and inflammation.Results: The mean T2* of the primary tumor and adjacent parenchyma at 48 hours in group A were 22.11 ms and 16.34 ms, respectively; in group B, these values were 23.96 ms and 23.26 ms, respectively. The T2* difference between the tumor and adjacent parenchyma in group A was more pronounced compared to in group B. The tumor margins were subjectively more distinct in group A compared to group B. Histopathologic evaluation showed a rim of dense fibrosis with atrophic acini at the periphery of the lesion in group A. Conversely, intact tumor cells/glands were present at the periphery of the tumor in group B.Conclusion: Ferumoxytol-enhanced MRI scans in patients receiving preoperative neoadjuvant therapy may offer enhanced primary tumor delineation, contributing towards achieving disease-free margin at the time of surgery, and thus improving the prognosis of pancreatic carcinomas.Keywords: pancreatic cancer, tumor margin, neoadjuvant therapy, borderline resectable pancreatic cance

Magnetic resonance fingerprinting for simultaneous renal T₁ and T2* mapping in a single breath-hold

Purpose: To evaluate the use of magnetic resonance fingerprinting (MRF) for simultaneous quantification of T1 and T*2 in a single breath-hold in the kidneys. Methods: The proposed kidney MRF sequence was based on MRF echo-planar imaging. Thirty-five measurements per slice and overall 4 slices were measured in 15.4 seconds. Group matching was performed for in-line quantification of T1 and T*2. Images were acquired in a phantom and 8 healthy volunteers in coronal orientation. To evaluate our approach, region of interests were drawn in the kidneys to calculate mean values and standard deviations of the T1 and T*2 times. Precision was calculated across multiple repeated MRF scans. Gaussian filtering is applied on baseline images to improve SNR and match stability. Results: T1 and T*2 times acquired with MRF in the phantom showed good agreement with reference measurements and conventional mapping methods with deviations of less than 5% for T1 and less than 10% for T*2. Baseline images in vivo were free of artifacts and relaxation times yielded good agreement with conventional methods and literature (deviation T1:7 ± 4%, T*2:6±3%). Conclusions: In this feasibility study, the proposed renal MRF sequence resulted in accurate T1 and T*2 quantification in a single breath-hold.ImPhys/Quantitative Imagin