Prospective comparison of positron emission tomography (PET)/magnetic resonance and PET/computed tomography dosimetry in hepatic malignant neoplastic disease after 90Y radioembolization treatment.

Background: 90Y radioembolization is an established treatment modality for hepatic malignancies. Successful radioembolization requires optimal dose delivery to tumors while minimizing dosages to parenchyma. Post-treatment positron emission tomography (PET)/computed tomography (CT) dosimetry is the established benchmark, whereas PET/magnetic resonance (MR) is an emerging modality. The goal of this study was to assess the intermodality agreement between PET/MR and PET/CT 90Y dosimetry. Methods: In this single-institution study, 18 patients (20 treatment sessions) with a primary or metastatic hepatic malignancy underwent both PET/MR and PET/CT after 90Y radioembolization. Patients were randomized to undergo one modality first, followed by the other. The region of interest was delineated using MR images and tumor and liver dosimetry was calculated. Intermodality agreement was assessed using the Bland-Altman method. A generalized linear model was used to assess the effect of baseline variables on intermodality dose differences. Results: PET/MR underestimated tumor and liver absorbed doses when compared to PET/CT by -3.7% (P=0.042) and -5.8% (P=0.029), respectively. A coverage probability plot demonstrated that 80% and 90% of tumor dose measurements fell within intermodality differences of 11% and 18%, respectively. PET/MR underestimated tumor dose at both low (<1 GBq) and high (>3 GBq) injected activity levels (P<0.001) by -22.3 [standard deviation (SD) =13.5] and -24.3 (SD =18.7), respectively. Conclusions: Although PET/MR significantly underestimated the absorbed dose when compared to PET/CT, the intermodality agreement was high and the degree of underestimation was better than previously reported. Intermodality differences were more pronounced at low and high injected doses. Additional studies are required to assess the clinical implications of these findings.

Computed Tomography-Guided Pericardiocentesis: A Practical Guide.

PURPOSE OF REVIEW: The purpose of this article is to serve as a practical guide to computed tomography (CT)-guided pericardiocentesis and to discuss the role of this approach in current clinical practice. An overview of indications, technique, advantages, and limitations specific to CT-guided pericardiocentesis will be provided. The reader will have an enhanced understanding of the use of this imaging modality to guide pericardial drainage. RECENT FINDINGS: Use of CT guidance to drain the pericardial space is safe, especially when adequate echocardiographic evaluation is precluded and when echocardiography-guided pericardiocentesis is deemed unsafe and or not feasible. Our review and experience indicate that CT-guided pericardiocentesis is technically successful in more than 94% of patients, with a low risk (<1%) of significant complications. CT-guided pericardiocentesis is therefore a viable alternative when echocardiographic guidance is insufficient and can obviate the need for surgery in most patients.

Thoracic central venous occlusion from the interventional radiology perspective.

Central venous occlusion is a common condition in certain patient populations, with significant associated morbidity. Symptoms range from mild arm swelling to respiratory distress and can be particularly troublesome in the end stage renal disease population when related to dialysis access and function. Crossing completely occluded vessels is often the most challenging step and various techniques exist to accomplish this. Traditionally, blunt and sharp recanalization techniques are used to cross occluded vessels and are described in detail. Even with experienced providers there are lesions which prove to be too difficult and are refractory to traditional approaches. We discuss advanced techniques such as with radiofrequency guidewires as well as newer technologies which offer an alternative pathway to re-establishing access. These emerging methods have demonstrated procedural success in the majority of cases where traditional techniques were futile. Following recanalization, angioplasty with or without stenting is typically performed and restenosis is a commonly encountered complication. We discuss angioplasty and the emerging use of drug-eluting balloons in venous thrombosis. Subsequently, in regards to stenting we discuss the indications and multitude of available types including novel venous stents with their respective strengths and drawbacks. Potential feared complications such as venous rupture with balloon angioplasty and stent migration are discussed along with our recommendations to reduce their risk of occurrence and promptly manage them when they do unfortunately occur.

Semiautomatic Cone-Beam Computed Tomography Virtual Hepatic Volumetry for Intra-Arterial Therapies.

PURPOSE: To evaluate a software simulating the perfused liver volume from virtual selected embolization points on proximal enhanced cone-beam computed tomography (CT) liver angiography data set using selective cone-beam CT as a reference standard. MATERIALS AND METHODS: Seventy-eight selective/proximal cone-beam CT couples in 46 patients referred for intra-arterial liver treatment at 2 recruiting centers were retrospectively included. A reference selective volume (RSV) was calculated from the selective cone-beam CT by manual segmentation and was used as a reference standard. The virtual perfusion volume (VPV) was then obtained using Liver ASSIST Virtual Parenchyma software on proximal cone-beam CT angiography using the same injection point as for selective cone-beam CT. RSV and VPV were then compared as absolute, relative, and signed volumetric errors (ABSErr, RVErr, and SVErr, respectively), whereas their spatial correspondence was assessed using the Dice similarity coefficient. RESULTS: The software was technically successful in automatically computing VPV in 74 of 78 (94.8%) cases. In the 74 analyzed couples, the median RSV was not significantly different from the median VPV (394 mL [196-640 mL] and 391 mL [192-620 mL], respectively; P = .435). The median ABSErr, RVErr, SVErr, and Dice similarity coefficient were 40.9 mL (19.9-97.7 mL), 12.8% (5%-22%), 9.9 mL (-49.0 to 40.4 mL), and 80% (76%-84%), respectively. No significant ABSErr, RVErr, SVErr, and Dice similarity coefficient differences were found between the 2 centers (P = .574, P = .612, P = .416, and P = .674, respectively). CONCLUSIONS: Perfusion hepatic volumes simulated on proximal enhanced cone-beam CT using the virtual parenchyma software are numerically and spatially similar to those manually obtained on selective cone-beam CT.

Restriction of congenital portosystemic shunt using the modified microvascular plug.

Congenital portosystemic shunts (CPSS) may produce a variety of severe, clinically detrimental presentations. When indicated, closure is recommended; however, if the intrahepatic portal venous system (IPVS) is underdeveloped complete closure may not be possible and may result in severe acute portal hypertension. Staged restriction of CPSS flow by both surgical and complex transcatheter interventions has been successful in augmenting development of the IPVS such that complete occlusion of the CPSS can be performed. We report use of a modified microvascular plug to restrict CPSS flow with subsequent IPVS development and safe complete occlusion of CPSS.

ACR Appropriateness Criteria® Radiologic Management of Lower Gastrointestinal Tract Bleeding: 2021 Update.

Diverticulosis remains the commonest cause for acute lower gastrointestinal tract bleeding (GIB). Conservative management is initially sufficient for most patients, followed by elective diagnostic tests. However, if acute lower GIB persists, it can be investigated with colonoscopy, CT angiography (CTA), or red blood cell (RBC) scan. Colonoscopy can identify the site and cause of bleeding and provide effective treatment. CTA is a noninvasive diagnostic tool that is better tolerated by patients, can identify actively bleeding site or a potential bleeding lesion in vast majority of patients. RBC scan can identify intermittent bleeding, and with single-photon emission computed tomography, can more accurately localize it to a small segment of bowel. If patients are hemodynamically unstable, CTA and transcatheter arteriography/embolization can be performed. Colonoscopy can also be considered in these patients if rapid bowel preparation is feasible. Transcatheter arteriography has a low rate of major complications; however, targeted transcatheter embolization is only feasible if extravasation is seen, which is more likely in hemodynamically unstable patients. If bleeding site has been previously localized but the intervention by colonoscopy and transcatheter embolization have failed to achieve hemostasis, surgery may be required. Among patients with obscure (nonlocalized) recurrent bleeding, capsule endoscopy and CT enterography can be considered to identify culprit mucosal lesion(s). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Lower extremity CT angiography in peripheral arterial disease: from the established approach to evolving technical developments.

With the advent of multidetector computed tomography (CT), CT angiography (CTA) has gained widespread popularity for noninvasive imaging of the arterial vasculature. Peripheral extremity CTA can nowadays be performed rapidly with high spatial resolution and a decreased amount of both intravenous contrast and radiation exposure. In patients with peripheral artery disease (PAD), this technique can be used to delineate the bilateral lower extremity arterial tree and to determine the amount of atherosclerotic disease while differentiating between acute and chronic changes. This article provides an overview of several imaging techniques for PAD, specifically discusses the use of peripheral extremity CTA in patients with PAD, clinical indications, established technical considerations and novel technical developments, and the effect of postprocessing imaging techniques and structured reporting.

ACR appropriateness criteria radiologic management of lower gastrointestinal tract bleeding: 2021 update

Diverticulosis remains the commonest cause for acute lower gastrointestinal tract bleeding (GIB). Conservative management is initially sufficient for most patients, followed by elective diagnostic tests. However, if acute lower GIB persists, it can be investigated with colonoscopy, CT angiography (CTA), or red blood cell (RBC) scan. Colonoscopy can identify the site and cause of bleeding and provide effective treatment. CTA is a noninvasive diagnostic tool that is better tolerated by patients, can identify actively bleeding site or a potential bleeding lesion in vast majority of patients. RBC scan can identify intermittent bleeding, and with single-photon emission computed tomography, can more accurately localize it to a small segment of bowel. If patients are hemodynamically unstable, CTA and transcatheter arteriography/embolization can be performed. Colonoscopy can also be considered in these patients if rapid bowel preparation is feasible. Transcatheter arteriography has a low rate of major complications; however, targeted transcatheter embolization is only feasible if extravasation is seen, which is more likely in hemodynamically unstable patients. If bleeding site has been previously localized but the intervention by colonoscopy and transcatheter embolization have failed to achieve hemostasis, surgery may be required. Among patients with obscure (nonlocalized) recurrent bleeding, capsule endoscopy and CT enterography can be considered to identify culprit mucosal lesion(s). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Comparison of Fit for Sealed and Loose-Fitting Surgical Masks and N95 Filtering Facepiece Respirators.

OBJECTIVES: N95 filtering facepiece respirators (N95 FFRs) and surgical masks are comprised of multiple layers of nonwoven polypropylene. Tight-fitting N95 FFRs are respiratory protective devices (RPDs) designed to efficiently filter aerosols. During the COVID-19 pandemic, health care workers (HCWs) throughout the world continue to face shortages of disposable N95 FFRs. Existing version of widely available FDA cleared loose-fitting surgical masks with straps do not provide reliable protection against aerosols. We tested the faceseal of a modified strapless form-fitting sealed version of surgical mask using quantitative fit testing (QNFT) and compared the performance of this mask with that of N95 FFRs and unmodified loose-fitting surgical masks. METHODS: Twenty HCWs participated in the study (10 women; 10 men; age 23-59 years). To create the sealed surgical masks, we removed the straps from loose-fitting surgical masks, made new folds, and used adhesive medical tape to secure the new design. All participants underwent QNFT with a loose-fitting surgical mask, the sealed surgical mask, and an N95 FFR; fit factors were recorded. Each QNFT was performed using a protocol of four exercises: (i) bending over, (ii) talking, (iii) moving head side to side, and (iv) moving head up and down. When the overall fit factor for the sealed surgical mask or N95 FFR was <100, the participant retook the test. Participants scored the breathability and comfort of the sealed surgical mask and N95 FFR on a visual analog scale (VAS) ranging from 0 (unfavorable) to 10 (favorable). RESULTS: The median fit factor for the sealed surgical mask (53.8) was significantly higher than that of the loose-fitting surgical mask (3.0) but lower than that of the N95 FFR (177.0) (P < 0.001), equating to significantly lower inward leakage of ambient aerosols (measuring 0.04-0.06 µm) with the sealed surgical mask (geometric mean 1.79%; geometric standard deviation 1.45%; range 0.97-4.03%) than with the loose-fitting surgical mask (29.5%; 2.01%; 25-100.0%) but still higher than with the N95 FFR (0.66%; 1.46%; 0.50-1.97%) (P < 0.001). Sealed surgical masks led to a marked reduction (range 60-98%) in inward leakage of aerosols in all the participants, compared to loose-fitting surgical masks. Among the exercises, talking had a greater effect on reducing overall fit factor for the sealed surgical mask than for the N95 FFR; when talking was excluded, the fit factor for the sealed surgical mask improved significantly (median 53.8 to 81.5; P < 0.001). The sealed surgical mask, when compared with the N95 FFR, offered better reported breathability (median VAS 9 versus 5; P < 0.001) and comfort (9 versus 5; P < 0.001). CONCLUSIONS: Widely available loose-fitting surgical masks can be easily modified to achieve faceseal with adhesives. Unlike loose-fitting surgical masks, sealed surgical masks can markedly reduce inward leakage of aerosols and may therefore offer useful levels of respiratory protection during an extreme shortage of N95 FFRs and could benefit HCWs who cannot comply with N95 FFRs due to intolerance. However, because a wide range of surgical masks is commercially available, individual evaluation of such masks is highly recommended before sealed versions are used as RPDs.

Independent usefulness of flow phase 99mTc-red blood cell scintigraphy in predicting the results of angiography in acute gastrointestinal bleeding.

OBJECTIVE:: In acute gastrointestinal bleeding, despite positive dynamic phase 99mTc-red blood cell scintigraphy, invasive catheter angiography (CA) is frequently negative. In this study, we investigated the value of flow phase scintigraphy in predicting extravasation on CA. METHODS:: Institutional review board approval with a waiver of informed consent was obtained for this retrospective study. A total of 173 scintigraphy procedures performed in 145 patients with GIB between January 2013 and August 2014 were analysed. Scintigraphy had two phases: flow (1 image/s for 1 min) followed by dynamic (1 image/30 s for 1 h). Patients who underwent CA within 24 hours of positive scintigraphy were assessed. Each scintigraphy phase was randomly and independently reviewed by two nuclear medicine physicians blinded to the outcomes of the other phase and of CA. RESULTS:: A total of 42 patients (29%) had positive scintigraphy. Of these patients, 29 underwent CA, and extravasation was seen in 6 (21%). In all, dynamic phase scintigraphy was positive. 13 of the 29 patients also had positive flow phase scintigraphy. The sensitivity, specificity, positive-predictive value, and negative-predictive value of flow phase scintigraphy for extravasation on CA were 100, 70, 46, and 100%, respectively. Specificity and positive predictive value were higher when CA was performed within 4 hours of positive flow phase scintigraphy. CONCLUSIONS:: Negative flow phase scintigraphy can identify patients who will not benefit from CA despite positive dynamic phase scintigraphy. The likelihood of extravasation on CA is higher when performed soon after positive flow phase scintigraphy. ADVANCES IN KNOWLEDGE:: Negative flow phase scintigraphy identifies patients who will not benefit from invasive catheter angiography despite positive results on subsequent dynamic phase scintigraphy. Increasing the delay between positive red blood cell scintigraphy and catheter angiography progressively reduces the likelihood of identifying extravasation, which is required to target embolization.

Congenital Anomalies of the Superior Vena Cava: Embryological Correlation, Imaging Perspectives, and Clinical Relevance.

There is a wide spectrum of congenital anomalies of the superior vena cava, which are more increasingly recognized in cross-sectional imaging. Although some of these anomalies are asymptomatic, others have important clinical and interventional implications. Imaging modalities such as computed tomography and magnetic resonance imaging play an important role in the accurate characterization of these anomalies, which is essential for mapping prior to surgeries or interventions. In this article, we review a wide range of anomalies of the superior vena cava, including the embryological basis, cross-sectional imaging findings, and clinical implications, particularly from an interventional radiology perspective. We also discuss the treatments and complications of these anomalies.

Pulmonary thromboendarterectomy in the setting of a mediastinal venous malformation with a congenitally absent left subclavian vein.

Venous malformations have static venous lakes that predispose to spontaneous venous thrombosis within the malformation due to its low-flow static state. Thrombi of varying sizes can then embolize continually into the pulmonary arterial circulation, and occlude and narrow elastic pulmonary arteries causing chronic thromboembolic pulmonary hypertension (CTEPH). Pulmonary thromboendarterectomy (PTE) is potentially curative in CTEPH, but has not been previously reported in the setting of mediastinal and chest wall venous malformations. We report the case of a 21-year-old female with such a large malformation treated successfully with PTE. The patient underwent complete endovascular reconstruction of her subclavian vein system from the axillary vein to the innominate vein stump with covered stent grafts to exclude the malformations from causing recurrent pulmonary emboli. This was followed by embolization of the malformation to allow for the surgical approach. The series of events in this case serves as a novel approach in managing such rare patients.

A "Train-Track" Technique in Anatomic Reconstruction of SVC Bifurcation Complicated by Cardiac Tamponade: An Introspection.

This report describes a stenting technique used to anatomically reconstruct superior vena cava (SVC) bifurcation in a patient with benign SVC syndrome. After recanalizing the SVC bifurcation, we exchanged two 0.035-in. wires for two 0.018-in. wires, deployed the SVC stent over these two wires ("train-track" technique), and stented each innominate vein over one wire. However, our decisions to recanalize both innominate veins, use the "buddy-wire" technique for SVC dilation, and dilate the SVC to 16 mm before stent deployment likely contributed to SVC tear, which was managed by resuscitation, SVC stent placement, and pericardial drainage. Here, we describe the steps of the train-track technique, which can be adopted to reconstruct other bifurcations; we also discuss the controversial aspects of this case.

Predictors of Successful Downstaging of Hepatocellular Carcinoma Outside Milan Criteria.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) outside Milan criteria (MC) may be candidates for liver transplantation (LT) after successful downstaging. Factors that predict successful downstaging are unclear. We aimed to identify the predictors of successful downstaging of HCC in patients outside MC. METHODS: We performed a retrospective cohort study on consecutive patients with HCC outside MC who received downstaging with locoregional therapy. Clinical and laboratory variables, tumor characteristics including total tumor volume (TTV) and up-to-7 criteria were recorded. We performed univariate and multivariate logistic regression analyses to identify variables associated with successful downstaging. RESULTS: Of 675 patients with HCC, 90 patients outside MC received downstaging. Fifty-three (59%) patients were successfully downstaged, 37 (41%) failed downstaging. University of California at San Francisco criteria, α-fetoprotein, up-to-7 criteria, TTV, and platelet count were predictors of successful downstaging on univariate analysis. Total tumor volume was an independent predictor of successful downstaging on multivariate logistic regression (P = 0.04, area under receiver operating characteristic curve 0.89 (95% confidence interval, 0.82-0.96). Fifty-two (76%) of 68 patients with TTV less than 200 cm were successfully downstaged, whereas only 1 (4.5%) of 22 patients with TTV greater than 200 cm were successfully downstaged. Forty-five (50%) patients underwent LT. Kaplan-Meier survival rates at 1 and 5 years post-LT were 95.3% and 79.4%, respectively. Patients who were successfully downstaged had better survival than patients who failed downstaging (P < 0.01). CONCLUSIONS: Total tumor volume is a good predictor of successful downstaging of HCC. Patients with TTV less than 200 cm may be considered good candidates for downstaging. Further studies with larger cohort of patients are needed to validate this approach in patients with HCC outside Milan.

Billowing Of Endologix Powerlink Stent Mimicking Endoleaks.

INTRODUCTION: Endoleaks remains one of the primary concerns of endovascular aortic aneurysm repair (EVAR) and is routinely followed with CT angiography (CTA). However, certain imaging findings can mimic endoleaks. CASE PRESENTATION: A 65-year-old woman who had endovascular aortic repair (EVAR) of an abdominal aortic aneurysm with Endologix Powerlink system developed marked new circumferential cauliflower-like bulging of contrast-filled sacs at mid-stent-graft with enlargement of the excluded aneurysm at 3-year follow-up. CONCLUSIONS: Considering the unique construct of the Powerlink stents, this is thought to represent aneurysmal degeneration of the outer fabric material from the metal struts and may potentially pressurize the excluded sac with risk for rupture.

Congenital anomalies of the IVC-embryological perspective and clinical relevance.

With the increased use of cross-sectional imaging, systemic venous anomalies are more frequently being recognized in asymptomatic patients. Accurate characterization of systemic venous anomalies plays a major role in the appropriate selection of a surgical approach or interventional procedure. In this article, we review common and uncommon inferior vena cava (IVC) anomalies. We describe the embryological basis and clinical implications of these anomalies, particularly from an interventional radiology perspective. We also discuss the complications and treatments of these anomalies.

Utility of cone-beam computed tomography in the assessment of the porto-spleno-mesenteric venous system.

The common diagnostic tools available to evaluate the porto-spleno-mesenteric venous (PSMV) system provide either good hemodynamic information with limited morphological details [e.g., ultrasonography (US)] or excellent tomographic display of the anatomy with limited information about flow patterns [e.g., multidetector computed tomography (MDCT) and magnetic resonance imaging]. Although catheter-directed selective digital subtraction angiography (DSA) can provide excellent information about flow at a high temporal resolution and can generate images at a high spatial resolution, this technique is often limited by a lack of cross-sectional detail. In the assessment of the PSMV system, DSA is also limited by dilution of contrast and motion artefacts. Combining venous phase cone-beam computed tomography (CBCT) with DSA can generate high-quality tomographic data, which allows detailed evaluation of venous tributaries and flow patterns within the splenic, superior mesenteric, and inferior mesenteric venous systems individually. This enables clinicians to better understand the impact of nonobstructive resistance to flow (e.g., as in patients with cirrhosis) and obstructive resistance to flow (e.g., as in patients with thrombosis) within each system and plan treatment accordingly. In this review, we discuss the limitations of common diagnostic methods and the role venous CBCT in combination with DSA can play in assessing the PSMV system.