The utility of time resolved magnetic resonance angiography in differentiating vascular malformations.

PURPOSE: The objective is to show that TR-MRA is a useful non-invasive technique without ionizing radiation of traditional angiography in evaluating VMs. MATERIALS AND METHODS: Retrospective search utilizing M-Power for MRA studies done at 3 T (Trio, Siemens) with both 3D contrast enhanced TR-MRA and 3D CE-MRA sequences from 2009 to 2018 were obtained after IRB approval. The images were blindly reviewed by two experienced cardiovascular radiologists for informations regarding vascular malformations with the ability to separate arteries and veins without any overlay or contamination in real time. Both TR-MRA and 3D CE-MRA images were carefully evaluated. The following characteristics: flow rate, size, type, feeding vessels, draining vessels and clots were evaluated. The findings were then compared to the Catheter Angiography for the patients that had catheter angiography study. RESULTS: The M-Power search resulted a total of 69 patients (24 males, 45 females, age range 11 days to 74 years). Of those 69, there were 25 patients with confirmatory Catheter Angiography study. The radiologists characterized VMs as 19 high flow VMs, 47 slow flow VMs, 2 lymphatic malformations and 1 no flow VM. Of those with Cath, there was 100% concordance with the TR-MRA. CONCLUSION: TR-MRA provides functional characterization of a VM that cannot be determined with CE-MRA alone. This is critical in treatment planning with high-flow VMs.

An Image Quality-informed Framework for CT Characterization.

Background Lack of standardization in CT protocol choice contributes to radiation dose variation. Purpose To create a framework to assess radiation doses within broad CT categories defined according to body region and clinical imaging indication and to cluster indications according to the dose required for sufficient image quality. Materials and Methods This was a retrospective study using Digital Imaging and Communications in Medicine metadata. CT examinations in adults from January 1, 2016 to December 31, 2019 from the University of California San Francisco International CT Dose Registry were grouped into 19 categories according to body region and required radiation dose levels. Five body regions had a single dose range (ie, extremities, neck, thoracolumbar spine, combined chest and abdomen, and combined thoracolumbar spine). Five additional regions were subdivided according to dose. Head, chest, cardiac, and abdomen each had low, routine, and high dose categories; combined head and neck had routine and high dose categories. For each category, the median and 75th percentile (ie, diagnostic reference level [DRL]) were determined for dose-length product, and the variation in dose within categories versus across categories was calculated and compared using an analysis of variance. Relative median and DRL (95% CI) doses comparing high dose versus low dose categories were calculated. Results Among 4.5 million examinations, the median and DRL doses varied approximately 10 times between categories compared with between indications within categories. For head, chest, abdomen, and cardiac (3 266 546 examinations [72%]), the relative median doses were higher in examinations assigned to the high dose categories than in examinations assigned to the low dose categories, suggesting the assignment of indications to the broad categories is valid (head, 3.4-fold higher [95% CI: 3.4, 3.5]; chest, 9.6 [95% CI: 9.3, 10.0]; abdomen, 2.4 [95% CI: 2.4, 2.5]; and cardiac, 18.1 [95% CI: 17.7, 18.6]). Results were similar for DRL doses (all P < .001). Conclusion Broad categories based on image quality requirements are a suitable framework for simplifying radiation dose assessment, according to expected variation between and within categories. © RSNA, 2021 See also the editorial by Mahesh in this issue.

Multiple pulmonary artery mycotic aneurysms and septic emboli in a patient with tricuspid valve vegetation and infective endocarditis.

Mycotic pulmonary artery aneurysms are rare infectious aneurysmal dilatations of the pulmonary arteries in patients with risk factors of intravenous drug use, endocarditis, or congenital heart disease. Timely diagnosis is crucial given high mortality rate associated with this condition. We present a rare case of a 24-year old male with history of intravenous drug use who presented with fever, hypoxia, and bacteremia. The patient was subsequently diagnosed with infective endocarditis with septic vegetations of the tricuspid valve. Computed tomography angiogram demonstrated multiple bilateral mycotic pulmonary artery aneurysms and associated pulmonary septic emboli in this patient with infective endocarditis. Treatment options for mycotic pulmonary artery aneurysms are variable and include conservative management, endovascular coil intervention, or surgical resections. Presence of hemoptysis and increasing aneurysm size may warrant aggressive intervention.

Unusual presentation of testicular rhabdomyosarcoma metastases to the right ventricle papillary muscle and tricuspid valve.

Intracardiac metastasis of the testicular cancer is very rare phenomenon. A 30-year-old-man with a history of testicular rhabdomyosarcoma and lung metastases was found to have an intracardiac filling defect in a surveillance computed tomography scan 3 years after the initial diagnosis. A cardiac magnetic resonance imaging study was performed for further evaluation and demonstrated a lobulated, heterogeneously enhancing mobile mass within the right ventricle attaching to the anterior papillary muscle. Patient underwent an open surgical resection of the cardiac mass that was confirmed metastasis of testicular rhabdomyosarcoma into the right ventricular papillary muscle and tricuspid valve. To our knowledge, this is the first report in the literature that describes metastasis to a papillary muscle and tricuspid valve from a testicular neoplasm.

Unilateral absence of pulmonary artery and azygous continuation of interrupted inferior vena cava.

Unilateral absence of pulmonary artery is a rare developmental anomaly. Infrahepatic inferior vena cava interruption is a well-recognized but uncommon developmental anomaly. Presence of both these anomalies in a single individual is extremely rare. A 58-year-old man with a history of recurrent lower extremity deep vein thrombosis and venous insufficiency presented to our emergency department with bilateral calf pain and swelling. Ultrasound demonstrated extensive deep vein thrombosis throughout bilateral lower extremities. Computed tomography angiography showed smooth tapering of the right pulmonary artery with absent distal most segment. To our knowledge, there is only 1 case report in the literature so far with both the abnormalities present in a single individual.

Comparison of Ferumoxytol-enhanced MR Angiography and CT Angiography for the Detection of Pulmonary Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia: Initial Results.

PURPOSE: To perform a preliminary comparison of the sensitivity and positive predictive value of ferumoxytol-enhanced MR angiography with those of CT angiography for detection of pulmonary arteriovenous malformations (AVMs) in hereditary hemorrhagic telangiectasia (HHT). MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. Ten patients with pulmonary AVMs who had undergone CT of the chest within 12 months underwent MRI of the chest and abdomen with ferumoxytol at 3.0 T at a dose of 4 mg per kilogram of body weight. Consensus review of MR and CT images assessed the presence and characteristics of pulmonary AVMs, image quality, vessel visibility, and artifact grade. RESULTS: Forty-three AVMs were detected, 13 native and 30 recanalized. Twenty-one AVMs had a feeding artery diameter of greater than 2 mm, of which detection occurred in 19 (at MRI and CT), in two (at MRI only), and zero (at CT only). Twenty-two AVMs had a feeding artery diameter of less than or equal to 2 mm, of which detection occurred in 16 (at MRI and CT), six (at CT only), and zero (at MRI only). For the entire cohort, the sensitivity of ferumoxytol-enhanced MRI using CT as the reference standard was 85.4% (35 of 41), and the positive predictive value was 100% (35 of 35). No significant difference was found between CT and MRI in AVM size, feeding artery and draining vein diameter, and artifact score (P >.05 for all). CONCLUSION: Initial results suggest that ferumoxytol-enhanced MRI is a feasible alternative to CT for detection of pulmonary AVM in HHT, while avoiding repeated exposure to radiation, nephrotoxic contrast material, or gadolinium-based contrast agent.© RSNA, 2020.

Significance of Coronary Artery Calcium Found on Non-Electrocardiogram-Gated Computed Tomography During Preoperative Evaluation for Liver Transplant.

Guidelines to evaluate patients for coronary artery disease (CAD) during preoperative evaluation for orthotopic liver transplantation (OLT) are conflicting. Cardiac catheterization is not without risk in patients with end-stage liver disease. No study to date has looked at the utility of non-electrocardiogram-gated chest computed tomography (CT) in the preliver transplant population. Our hypothesis was that coronary artery calcium scores (CACSs) from chest CT scans ordered during the liver transplant workup can identify patients who would benefit from invasive angiography. Nine hundred and fifty-three patients who underwent coronary angiography as part of their OLT workup were considered. Charts were randomly selected and reviewed for the presence of a chest CT performed before coronary angiography during the OLT workup. Agatston and Weston scores were calculated. CACS results were compared with coronary angiography findings. Nine of 54 patients were found to have obstructive CAD by angiography. Receiver-operating characteristic analysis demonstrated that an Agatston score of 251 and a Weston score of 6 maximized sensitivity and specificity for detection of obstructive coronary disease. An Agatston score <4 or Weston score <2 excluded the presence of obstructive CAD; using these thresholds, 13 patients (24%) or 15 patients (28%), respectively, could have theoretically avoided catheterization without missing significant CAD. In conclusion, our data identify the strength of CACS in ruling out coronary disease in patients being evaluated for OLT. Calcium scoring from non-electrocardiogram-gated CT studies may be integrated into preoperative algorithms to rule out obstructive CAD and help avoid invasive angiography in this high-risk population.

High resolution, 3-dimensional Ferumoxytol-enhanced cardiovascular magnetic resonance venography in central venous occlusion.

BACKGROUND: Although cardiovascular magnetic resonance venography (CMRV) is generally regarded as the technique of choice for imaging the central veins, conventional CMRV is not ideal. Gadolinium-based contrast agents (GBCA) are less suited to steady state venous imaging than to first pass arterial imaging and they may be contraindicated in patients with renal impairment where evaluation of venous anatomy is frequently required. We aim to evaluate the diagnostic performance of 3-dimensional (3D) ferumoxytol-enhanced CMRV (FE-CMRV) for suspected central venous occlusion in patients with renal failure and to assess its clinical impact on patient management. METHODS: In this IRB-approved and HIPAA-compliant study, 52 consecutive adult patients (47 years, IQR 32-61; 29 male) with renal impairment and suspected venous occlusion underwent FE-CMRV, following infusion of ferumoxytol. Breath-held, high resolution, 3D steady state FE-CMRV was performed through the chest, abdomen and pelvis. Two blinded reviewers independently scored twenty-one named venous segments for quality and patency. Correlative catheter venography in 14 patients was used as the reference standard for diagnostic accuracy. Retrospective chart review was conducted to determine clinical impact of FE-CMRV. Interobserver agreement was determined using Gwet's AC1 statistic. RESULTS: All patients underwent technically successful FE-CMRV without any adverse events. 99.5% (1033/1038) of venous segments were of diagnostic quality (score ≥ 2/4) with very good interobserver agreement (AC1 = 0.91). Interobserver agreement for venous occlusion was also very good (AC1 = 0.93). The overall accuracy of FE-CMRV compared to catheter venography was perfect (100.0%). No additional imaging was required prior to a clinical management decision in any of the 52 patients. Twenty-four successful and uncomplicated venous interventions were carried out following pre-procedural vascular mapping with FE-CMRV. CONCLUSIONS: 3D FE-CMRV is a practical, accurate and robust technique for high-resolution mapping of central thoracic, abdominal and pelvic veins and can be used to inform image-guided therapy. It may play a pivotal role in the care of patients in whom conventional contrast agents may be contraindicated or ineffective.

Accelerated 3D bSSFP imaging for treatment planning on an MRI-guided radiotherapy system.

PURPOSE: The purpose of this study was to introduce a compressed sensing and parallel imaging-combined technique to reduce the acquisition time of planning MRI for MR-guided radiotherapy (MRgRT) systems. METHODS AND MATERIALS: A variable-density Poisson-Disk (VDPD) undersampling acquisition along with compressed sensing reconstruction technique was developed and compared with the current planning MR protocol, which uses an optimized balanced steady-state free precession sequence with 7.5-fold (7.5×) acceleration achieved by GRAPPA and partial Fourier. The image quality of GRAPPA and VDPD with 7.5× and 15× acceleration was compared with fully sampled images on a phantom. Two volunteers were recruited to compare the in vivo imaging performance. Ten patients with abdominal tumors were scanned using the conventional GRAPPA 7.5× (25 s) and the proposed VDPD 15× (12.5 s) sequences. Three readers scored the two approaches in terms of the quality for organ and tumor delineation. The gross tumor volume (GTV) and two kidneys were contoured. Differences in centroid location and contour volumes, Dice coefficients, and mean distance-to-agreement (MDA) between contours draw on the two techniques were calculated. All studies were performed on a 0.35 T MRgRT system. RESULTS: In the phantom study, VDPD with 15× acceleration rate had lower noise level than GRAPPA with 7.5× acceleration. In both the phantom and volunteer study, noise amplification was apparent when the acceleration rate was increased from 7.5× to 15× in the GRAPPA acquisition, whereas it was minimally increased using the VDPD approach. In the patient study, no significant difference was found for the scoring and contouring statistics between the two techniques, whereas VDPD only took half the scan time as GRAPPA. Volume difference for the GTV and two kidneys between GRAPPA 7.5× and VDPD 15× was around 7.6%, 1.3%, and 2.8%, respectively; while the Dice index was approximately 0.85, 0.92, and 0.90, respectively. CONCLUSION: The proposed technique reduced the acquisition time by half and provided comparable or improved image quality than the standard planning MRI protocol.

External Iliac Artery-Appendicular Fistula due to Antegrade Unusual Migration of K-Wire from Hip to Pelvis: An Unreported Complication.

Background. K-wires are thought to be extremely safe implants and complications as a result of direct insertion or migration are very rare. Complications may be life-threatening in some instances where migration results in injury to vital organs. We report one such case where antegrade migration of K-wire from the hip resulted in injury to external iliac artery and formation of external iliac artery-appendicular fistula. No such complication due to migration has ever been reported in the literature. Case Description. A 15-year-old boy presented with lower abdominal pain, right lower limb swelling and pain, inability to walk, and rectal bleeding for 1 month after 2 K-wires had been inserted in his right hip joint for treatment of slipped capital femoral epiphysis the previous year. On investigation, he was diagnosed to have external iliac artery-appendicular fistula for which he was surgically treated. Clinical Relevance. Antegrade migration of K-wire from hip joint may lead to life-threatening injuries which can be minimized by bending the end of the K-wire, keeping the tip protruding outside the skin wherever possible and by early removal of K-wire once its purpose has been achieved.