Steven Y. Huang

Kinetic Growth Rate after Portal Vein Embolization Predicts Posthepatectomy Outcomes: Toward Zero Liver-Related Mortality in Patients with Colorectal Liver Metastases and Small Future Liver Remnant

BACKGROUND Standardized future liver remnant (sFLR) volume and degree of hypertrophy after portal vein embolization (PVE) have been recognized as important predictors of surgical outcomes after major liver resection. However, the regeneration rate of the FLR after PVE varies among individuals and its clinical significance is unknown. STUDY DESIGN Kinetic growth rate (KGR) is defined as the degree of hypertrophy at initial volume assessment divided by number of weeks elapsed after PVE. In 107 consecutive patients who underwent liver resection for colorectal liver metastases with an sFLR volume >20%, the ability of the KGR to predict overall and liver-specific postoperative morbidity and mortality was compared with sFLR volume and degree of hypertrophy. RESULTS Using receiver operating characteristic analysis, the best cutoff values for sFLR volume, degree of hypertrophy, and KGR for predicting postoperative hepatic insufficiency were estimated as 29.6%, 7.5%, and 2.0% per week, respectively. Among these, KGR was the most accurate predictor (area under the curve 0.830 [95% CI, 0.736-0.923]; asymptotic significance, 0.002). A KGR of <2% per week vs ≥2% per week correlates with rates of hepatic insufficiency (21.6% vs 0%; p = 0.0001) and liver-related 90-day mortality (8.1% vs 0%; p = 0.04). The predictive value of KGR was not influenced by sFLR volume or the timing of initial volume assessment when evaluated within 8 weeks after PVE. CONCLUSIONS Kinetic growth rate is a better predictor of postoperative morbidity and mortality after liver resection for small FLR than conventional measured volume parameters (ie, sFLR volume and degree of hypertrophy).

Assessment of Vascular Contrast and Depiction of Stenoses in Abdominopelvic and Lower Extremity Vasculature: Comparison of Dual-energy MDCT with Digital Subtraction Angiography

RATIONALE AND OBJECTIVES To assess whether dual-energy computed tomography (DECT) multidetector computed tomography (MDCT) angiography improves vascular contrast beyond MDCT angiography and digital subtraction angiography (DSA) while preserving the ability to precisely characterize stenoses, using DSA as reference standard. MATERIALS AND METHODS This prospective, Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study was performed on 25 patients referred for lower extremity DECT angiography and subsequent DSA. Spectral data were postprocessed to create single-energy 120 kVp (MDCT series) and iodine-only (DECT series) datasets. The arterial tree was subdivided into 11 anatomical levels. Contrast-to-noise ratios (CNR) and corresponding coefficient -of variation (CV) of patent vessel segments were evaluated for DECT, MDCT, and DSA using analysis of variance comparisons. Degree of stenoses was determined for DECT, MDCT, and DSA and correlated with t-test, bivariate Pearson comparisons, and Bland-Altman plots. RESULTS Patent vasculature comprised 230 vessel segments. From infrarenal aorta to distal femoral arteries, DECT showed higher CNR compared to DSA and MDCT (P < .05); distal to the popliteal arteries, DSA achieved higher CNR (P < .05). Analyses of contrast homogeneity showed minimal CV above the knee for MDCT (≤9%) and for DSA below the knee (≤7%). Stenotic vasculature comprised 33 segments. Significant correlations of stenosis severity were found comparing DECT and MDCT with DSA as reference standard showing a 0.04-fold mean underestimation of stenoses on MDCT and no detectable mean variation on DECT compared with DSA. CONCLUSION DECT angiography improved contrast in vascular abdominopelvic and thigh distributions beyond MDCT angiography and DSA while preserving the ability to precisely assess severity of stenoses, using DSA as an accepted reference standard.

Efficacy and Safety of Portal Vein Embolization for Two-Stage Hepatectomy in Patients with Colorectal Liver Metastasis

PURPOSE To examine the efficacy and safety of portal vein embolization (PVE) when used during two-stage hepatectomy for bilobar colorectal liver metastases (CLM). MATERIALS AND METHODS PVE was performed as an adjunct to two-stage hepatectomy in 56 patients with CLM. Absolute future liver remnant (FLR) volumes, standardized FLR ratios, degree of hypertrophy (DH), and complications were analyzed. Segment II and III volumes and DH were also measured separately. All volumetric measurements were compared with a cohort of 96 patients (n = 37 right portal vein embolization [RPVE], n = 59 right portal vein embolization extended to segment IV portal veins [RPVE+4]) in whom PVE was performed before single-stage hepatectomy. RESULTS For patients who completed RPVE during two-stage hepatectomy (n = 17 of 17), mean absolute FLR volume increased from 272.1 cm(3) to 427.0 cm(3) (P < .0001), mean standardized FLR ratio increased from 0.17 to 0.26 (P < .0001), and mean DH was 0.094. For patients who completed RPVE+4 during two-stage hepatectomy (n = 38 of 39), mean FLR volume increased from 288.7 cm(3) to 424.8 cm(3) (P < .0001), mean standardized FLR increased from 0.18 to 0.26 (P < .0001), and mean DH was 0.083. DH of the FLR was not significantly different between two-stage hepatectomy and single-stage hepatectomy. Complications after PVE occurred in five (8.9%) patients undergoing two-stage hepatectomy. CONCLUSIONS PVE effectively and safely induced a significant DH in the FLR during two-stage hepatectomy in patients with CLM.

Abdominopelvic and Lower Extremity Deep Venous Thrombosis: Evaluation With Contrast-Enhanced MR Venography With a Blood-Pool Agent

OBJECTIVE The purpose of this article is to evaluate contrast-enhanced (CE) MR venography (MRV) with a blood-pool agent for detection of abdominopelvic and lower extremity deep venous thrombosis (DVT) compared with a conventional unenhanced gradient-recalled echo (GRE) MRV technique. MATERIALS AND METHODS This retrospective study was performed on 30 patients (mean age, 52.7 years; 15 men and 15 women) referred for MRV between March 2010 and November 2010 for evaluation of lower extremity or abdominopelvic DVT. All patients underwent a GRE sequence followed by a CE T1-weighted sequence with gadofosveset, a blood-pool agent. The abdominopelvic and lower extremity venous system was divided into 13 segments. The presence of acute or chronic DVT was assessed by six radiologists, as well as qualitative and quantitative assessments of each venous segment. Image acquisition and interpretation times were also tabulated. RESULTS The sensitivity and specificity for acute DVT were 91.0% and 99.8%, respectively, on CE MRV compared with 80.8% and 95.8%, respectively, on GRE MRV (p = 0.077 and p < 0.001). The sensitivity and specificity for chronic DVT were 84.4% and 98.4%, respectively, on CE MRV and 64.5% and 95.6%, respectively, on GRE MRV (p < 0.001 for both). Subjective ratings of vein visualization, signal homogeneity, and confidence pertaining to DVT diagnosis were significantly higher with the CE images (p < 0.001). The contrast-to-noise ratio for CE images was similar or significantly higher for all venous segments. Image acquisition and radiologist interpretation times on the CE studies were decreased (p < 0.001). CONCLUSION Gadofosveset-enhanced MRV had equal or higher sensitivity and specificity for detection of DVT than did GRE MRV, with decreased time for image acquisition and interpretation.

Management of Dysfunctional Catheters and Tubes Inserted by Interventional Radiology

Minimally invasive percutaneous interventions are often used for enteral nutrition, biliary and urinary diversion, intra-abdominal fluid collection drainage, and central venous access. In most cases, radiologic and endoscopic placement of catheters and tubes has replaced the comparable surgical alternative. As experience with catheters and tubes grows, it becomes increasingly evident that the interventional radiologist needs to be an expert not only on device placement but also on device management. Tube dysfunction represents the most common complication requiring repeat intervention, which can be distressing for patients and other health care professionals. This manuscript addresses the etiologies and solutions to leaking and obstructed feeding tubes, percutaneous biliary drains, percutaneous catheter nephrostomies, and drainage catheters, including abscess drains. In addition, we will address the obstructed central venous catheter.

Evaluation of liver fibrosis and hepatic venous pressure gradient with MR elastography in a novel swine model of cirrhosis

To assess the correlation among MR elastography (MRE) measured liver stiffness (LS), liver fibrosis, and hepatic venous pressure gradient (HVPG) in a swine model of cirrhosis.

Pilot in vivo study of an absorbable polydioxanone vena cava filter

OBJECTIVE The objectives of this study were to evaluate tensile strength retention of polydioxanone as a function of time in a swine venous system and to assess the feasibility of an absorbable inferior vena cava (IVC) filter made from polydioxanone in a pilot swine study. METHODS Twenty strands (60 cm each) of size 1 polydioxanone absorbable suture (Ethicon, Somerville, NJ) were placed in the central venous system of domestic swine. Strands were harvested at weekly intervals during 10 weeks for tensile strength testing. Results were compared with control samples obtained from an in vitro engineered circulation system containing sodium phosphate buffer solution. Three IVC filters braided from polydioxanone suture were also catheter deployed in three swine to assess absorbable IVC filter feasibility. RESULTS Polydioxanone retained 82% tensile strength in vitro vs 79% in vivo at 35 days (P > .22), the desired prophylactic duration. For IVC filters made from polydioxanone, technical success of placement was achieved in all three filters deployed (100%). Autologous thrombus deployed inferior to the filter remained trapped in the filter until thrombus resorption, with no evidence of pulmonary emboli on follow-up computed tomography. There were no instances of caval penetration, filter-induced IVC thrombosis, filter migration, or tilt >15 degrees with imaging and clinical follow-up carried out to 32 weeks. CONCLUSIONS Strength retention of polydioxanone suture placed in the venous system of swine is similar to earlier in vitro studies out to 10 weeks (P > .06 for all weeks) and is more than sufficient (8.20 ± 0.37 kg mean load at break for size 1) to trap thrombus. Pilot animal study suggests that an absorbable polydioxanone IVC filter can be catheter deployed to capture and to hold iatrogenically administered autologous thrombus through resorption.

Large Hiatal Hernia with Floppy Fundus: Clinical and Radiographic Findings

OBJECTIVE The purpose of this study was to compare the clinical and barium radiographic findings for 17 patients with large hiatal hernias and a floppy fundus with those for 61 patients with large hiatal hernias but no floppy fundus. CONCLUSIONS Patients with large hiatal hernias can develop a floppy fundus, which has a characteristic appearance on barium studies because it droops below the most superior portion of the herniated gastric body. Distortion of the gastric anatomy in patients with this type of hernia can cause mechanical symptoms that usually resolve after surgical repair of the hernia. Radiologists should be aware of the barium radiographic findings associated with a floppy fundus and of the potential role of surgery in the treatment of patients with symptoms.

Prevention and Management of Infectious Complications of Percutaneous Interventions

Infectious complications following interventional radiology (IR) procedures can cause significant patient morbidity and, potentially, mortality. As the number and breadth of IR procedures grow, it becomes increasingly evident that interventional radiologists must possess a thorough understanding of these potential infectious complications. Furthermore, given the increasing incidence of antibiotic-resistant bacteria, emphasis on cost containment, and attention to quality of care, it is critical to have infection control strategies to maximize patient safety. This article reviews infectious complications associated with percutaneous ablation of liver tumors, transarterial embolization of liver tumors, uterine fibroid embolization, percutaneous nephrostomy, percutaneous biliary interventions, central venous catheters, and intravascular stents. Emphasis is placed on incidence, risk factors, prevention, and management. With the use of these strategies, IR procedures can be performed with reduced risk of infectious complications.

Primary lung and large airway neoplasms in children. Current imaging evaluation with multidetector computed tomography.

Multidetector computed tomography (MDCT) offers an important noninvasive imaging modality for confirmation and further characterization of primary lung and large airway neoplasms encountered in pediatric patients. Children represent a unique challenge in imaging, not only because of unique patient factors (eg, inability to follow instructions, motion, need for sedation) but because of the technical factors that must be optimized to reduce radiation dose. This article reviews an MDCT imaging algorithm, up-to-date imaging techniques, and clinical applications of MDCT for evaluating benign and malignant primary neoplasms of lung and large airway in infants and children.