Computed Tomography-Based Preoperative Simulation System for Pedicle Screw Fixation in Spinal Surgery.

BACKGROUND: A preoperative planning system facilitates improving surgical outcomes that depend on the experience of the surgeons, thanks to real-time interaction between the system and surgeons. It visualizes intermediate surgical planning results to help surgeons discuss the planning. The purpose of this study was to demonstrate the use of a newly-developed preoperative planning system for surgeons less experienced in pedicle-screw fixation in spinal surgery, especially on patients with anatomical variations. METHODS: The marching cubes algorithm, a typical surface extraction technique, was applied to computed tomography (CT) images of vertebrae to enable three-dimensional (3D) reconstruction of a spinal mesh. Real-time processing of such data is difficult, as the surface mesh extracted from high-resolution CT data is rough, and the size of the mesh is large. To mitigate these factors, Laplacian smoothing was applied, followed by application of a quadric error metric-based mesh simplification to reduce the mesh size for the level-of-detail (LOD) image. Taubin smoothing was applied to smooth out the rough surface. On a multiplanar reconstruction (MPR) cross-sectional image or a 3D model view, the insertion position and orientation of the pedicle screw were manipulated using a mouse. The results after insertion were then visualized in each image. RESULTS: The system was used for pre-planning pedicle-screw fixation in spinal surgery. Using any pointing device such as a mouse, surgeons can manipulate the position and angle of the screws. The pedicle screws were easy to manipulate intuitively on the MPR images, and the accuracy of screw fixation was confirmed on a trajectory view and 3D images. After surgery, CT scans were performed again, and the CT images were checked to ensure that the screws were inserted properly. CONCLUSION: The preoperative planning system allows surgeons and students who are not familiar with pedicle-screw fixation to safely undertake surgery following preoperative planning. It also provides opportunities for screw-fixation training and simulation.

Delayed, life-threatening hemorrhage after self-expandable metallic biliary stent placement: clinical manifestations and endovascular treatment.

BACKGROUND: Life-threatening, delayed hemorrhage after self-expandable metallic stent (SEMS) insertion for malignant biliary obstruction is very rare. Clinical manifestations, radiologic characteristics, treatment, and prognosis of this complication are not well-known. PURPOSE: To present the clinical manifestations, radiologic findings, and endovascular treatment of life-threatening, delayed hemorrhage secondary to SEMS placement. MATERIAL AND METHODS: A total of six patients (five men and one woman; mean age, 65.5 years) with life-threatening, delayed arterial bleeding after SEMS placement for malignant bile duct obstruction were recruited between 2000 and 2011 from three different hospitals in Korea. The original SEMS placement in all patients utilized either percutaneous (n = 3) or endoscopic approaches (n = 3). We retrospectively reviewed the clinical presentations, computed tomography (CT) and angiographic findings, endovascular treatments, and prognoses of these patients. RESULTS: All patients presented with life-threatening gastrointestinal bleeding such as melena (n = 4), hematochezia (n = 1), and hematemesis (n = 1). Mean time period between biliary metallic stent insertion and presentation with bleeding was 75 days (range, 15-152 days). All stents were encased by primary or metastatic cancer along with nearby arteries on CT images. Digital subtraction angiogram (DSA) revealed pseudoaneurysm close to the stent (n = 2), in-stent pseudoaneurysm (n = 2), arteriobiliary fistula (n = 1), or pseudoaneurysm with arteriobiliary fistula (n = 1). The origins of hemorrhage were the gastroduodenal artery (n = 3), the aberrant right posterior hepatic artery from the gastroduodenal artery (n = 2), and the right hepatic artery (n = 1). Hemorrhages were successfully controlled after intra-arterial coil embolization in five patients followed by placement of a stent graft and direct puncture N-butyl-2-cyanoacrylate (NBCA) embolization in one patient. CONCLUSION: Life-threatening, delayed hemorrhage within a metallic biliary stent may occur if a stent is placed across the bulky bile duct tumor or tumor encases the stent. Bleeding can be successfully treated with endovascular treatment. However, the overall prognosis was poor.

Comparison of Clinical Efficacy and Safety between 70-150 µm and 100-300 µm Doxorubicin Drug-Eluting Bead Transarterial Chemoembolization for Hepatocellular Carcinoma.

BACKGROUND: This study aimed to compare the efficacy and safety of 70-150 µm doxorubicin drug-eluting bead (DEB) transarterial chemoembolization (TACE) with those of 100-300 µm DEB-TACE as first-line treatment in patients with hepatocellular carcinoma (HCC). METHODS: We retrospectively investigated 72 patients who underwent TACE with 70-150 µm DEBs (n = 40) or 100-300 µm DEBs (n = 32) for HCC in a tertiary center between March 2013 and May 2019. Initial treatment response and adverse events were assessed using the modified Response Evaluation Criteria in Solid Tumors and the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0, respectively. RESULTS: At the 2-month post-treatment assessment, the complete and objective response rates were 47.5% and 85.0%, respectively, for the 70-150 µm group and 34.4% and 81.3%, respectively, for the 100-300 µm group; however, the difference was not statistically significant (p > 0.05). In total, 65% patients in the 70-150 µm group and 59.4 % patients in the 100-300 µm group experienced at least one symptom of post-embolization syndrome after TACE; all symptoms were classified as grade 1 or 2. There was no significant difference between the two groups in terms of post-procedural laboratory changes such as changes in liver enzymes and bilirubin levels (p > 0.05). Laboratory toxicity of grade 3 occurred in three patients, all of which were transient elevation of liver enzyme levels. Hepatobiliary adverse events, such as bile duct injury, biloma, liver abscess, and hepatic infarction, were not observed in either treatment group. CONCLUSION: This study found no significant difference in tumor response between 70-150 µm and 100-300 µm DEB-TACE. Both groups showed favorable safety profiles, and the difference was not significant.

Use of covered stents in the central vein: a feasibility study in a canine model.

PURPOSE: To evaluate the feasibility of using covered stents vs. bare stents in a model of central vein stenosis with an arteriovenous graft created to mimic the conditions in hemodialysis patients. METHODS: In 7 mongrel dogs, an expanded polytetrafluoroethylene-covered nitinol stent was placed in one common iliac vein and a bare stent was placed in the contralateral vein. Arteriovenous grafts were created bilaterally between the common femoral artery and vein to induce endothelial damage. Neointima formation in the covered stents was compared to the bare stents at 12 weeks using microscopy and histochemical staining. RESULTS: Two dogs were excluded due to thrombosis and infection of the arteriovenous grafts, but all stents in the remaining 5 dogs were patent. Smooth, complete neointimal coverage was observed on the inner surface of all the covered stents without intraluminal thrombus. In contrast, incomplete neointimal coverage was seen in all bare stents, with small focal thrombi adhering to the neointima on 3 bare stents. Focal nodular neointimal hyperplasia with denudation of the endothelium was observed in only 2 bare stents. Mean neointimal thickening was significantly greater in the covered stents. Eccentric neointimal thickening was observed at the inflow and outflow segments of both types of stents. CONCLUSION: Covered stents are technically feasible for the treatment of central vein stenosis, and they demonstrate complete, smooth neointimal coverage in normal central veins, but they also display greater neointimal thickening than bare stents.

Outcome and prognostic factors of spontaneous ruptured hepatocellular carcinoma treated with transarterial embolization.

BACKGROUND: Rupture of hepatocellular carcinoma (HCC) is a life-threatening condition accompanied by hemorrhage. Transarterial embolization/chemoembolization (TAE/TACE) can be used as the first-line treatment to achieve initial homeostasis. PURPOSE: To investigate the outcome of TAE/TACE for spontaneous ruptured HCC and to determine the prognostic factors affecting survival. MATERIAL AND METHODS: We retrospectively reviewed the clinicoradiologic data of 47 patients (8 women, 39 men; median age 64.4 years) with serum bilirubin levels <3.0 mg/dL that underwent TAE/TACE for ruptured HCC between January 2004 and June 2010. Survival rates were estimated using the Kaplan-Meier method and prognostic factors of poor survival were obtained by univariate and multivariate analyses. RESULTS: The clinical success rate of TAE/TACE was 94% (44/47). The median survival time was 179.6 days. The 1-month, 3-month, 6-month, and 12-month survival rates were 75%, 54%, 48%, and 43%, respectively. Old age, a previous history of TACE for HCC, low initial hemoglobin level, higher blood transfusion requirement, Child-Pugh class C, high serum bilirubin level, low serum albumin level, prolonged prothrombin time, high serum creatinine level on admission, presence of encephalopathy, severe ascites, lobar TAE/TACE, presence of portal vein thrombosis, and tumors involving both lobes were associated with poor survival. Multivariate analysis revealed that higher blood transfusion requirement, Child-Pugh class C, presence of portal vein thrombosis, and tumors involving both lobes were significant predictors of poor survival. CONCLUSION: TAE/TACE is effective for achieving initial hemostasis, which is critical to survival. Regardless of successful TAE/TACE, the survival rate in patients with Child-Pugh class C remains poor. Portal vein thrombosis and tumor extent are significant image parameters for predicting survival after TAE/TACE for ruptured HCC.

Aortoesophageal fistula secondary to placement of an esophageal stent: emergent treatment with cyanoacrylate and endovascular stent graft.

We report on N-butyl 2-cyanoacrylate embolization and subsequent endovascular stent graft placement for the treatment of an aortoesophageal fistula secondary to placement of an esophageal stent. A 53-year-old man with lung cancer was admitted with massive hematemesis due to the formation of an aortoesophageal fistula 20 days after esophageal stent placement. Injection of N-butyl 2-cyanoacrylate into the aortoesophageal fistula was performed as emergent treatment for this hemodynamically unstable condition, and an endovascular stent graft was subsequently placed via the right femoral artery. The patient was well without hematemesis until he died of pneumonia 45 days later. Cyanoacrylate embolization and subsequent endovascular stent graft placement for the treatment of massive hemorrhage caused by an aortoesophageal fistula is a prompt, effective method and can be an alternative to surgical repair.

Multidetector CT diagnosis of non-traumatic gastroduodenal perforation.

INTRODUCTION: To identify reliable CT features and assess the diagnostic performance of 64-multidetector CT (MDCT) in diagnosing non-traumatic gastroduodenal perforation (GDP). METHODS: We retrospectively reviewed 136 CT scans of patients with surgically proven non-traumatic gastrointestinal perforation during 7 years. 92 patients had GDP and 44 patients had other sites of perforation. CT features of perforation were evaluated and the sensitivity, specificity and likelihood ratios of each CT feature were estimated. RESULTS: The cause of GDP was peptic ulcer in 90 patients, gastric cancer in one patient, and foreign body of duodenal diverticulum in one patient. Extraluminal gas (97%) was most common CT feature of GDP, following by fluid or fat strand along gastroduodenum (89%), ascites (89%), wall defect and/or ulcer (84%), and wall thickening (72%). Of CT features, wall defect and/or ulcer showed the best positive likelihood ratios for GDP (36.83). Wall thickening also showed high positive likelihood ratios (10.52). Combined, these CT features showed 95% sensitivity and 93% specificity for localization of perforation site of GDP. CONCLUSION: MDCT is useful in diagnosis of presence and site of GDP. Wall defect and/or ulcer and wall thickening have a high positive predictive value for localization of perforation site.

Feasibility of low-concentration iodinated contrast medium with lower-tube-voltage dual-source CT aortography using iterative reconstruction: comparison with automatic exposure control CT aortography.

To evaluate the feasibility of low-concentration contrast medium (CM) for vascular enhancement, image quality, and radiation dose on computed tomography aortography (CTA) using a combined low-tube-voltage and iterative reconstruction (IR) technique. Ninety subjects underwent dual-source CT (DSCT) operating in dual-source, high-pitch mode. DSCT scans were performed using both high-concentration CM (Group A, n = 50; Iomeprol 400) and low-concentration CM (Group B, n = 40; Iodixanol 270). Group A was scanned using a reference tube potential of 120 kVp and 120 reference mAs under automatic exposure control with IR. Group B was scanned using low-tube-voltage (80 or 100 kVp if body mass index ≥25 kg/m(2)) at a fixed current of 150 mAs, along with IR. Images of the two groups were compared regarding attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), iodine load, and radiation dose in various locations of the CTA. In comparison between Group A and Group B, the average mean attenuation (454.73 ± 86.66 vs. 515.96 ± 101.55 HU), SNR (25.28 ± 4.34 vs. 31.29 ± 4.58), and CNR (21.83 ± 4.20 vs. 27.55 ± 4.81) on CTA in Group B showed significantly greater values and significantly lower image noise values (18.76 ± 2.19 vs. 17.48 ± 3.34) than those in Group A (all Ps < 0.05). Homogeneous contrast enhancement from the ascending thoracic aorta to the infrarenal abdominal aorta was significantly superior in Group B (P < 0.05). Low-concentration CM and a low-tube-voltage combination technique using IR is a feasible method, showing sufficient contrast enhancement and image quality.

Diagnostic performance of 64-MDCT for blunt small bowel perforation.

OBJECTIVE: The objective was to assess the diagnostic performance of 64-multidetector computed tomography (CT) for blunt small bowel perforation (BSBP). MATERIALS AND METHODS: The study included 106 CT examinations of surgically proven blunt bowel and mesentery injuries (78 of BSBP and 28 of non-BSBP). CT diagnosis was based on detection of bowel wall discontinuity or extraluminal gas. RESULTS: Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT diagnosis were 84.0%, 79.5%, 96.4%, 98.4%, and 62.8%, respectively. Bowel wall discontinuity and extraluminal gas were detected on 19.2% and 74.4% examination, respectively. CONCLUSION: CT diagnosis of BSBP is highly specific but not sensitive.

Comparison of internally cooled wet electrode and hepatic vascular inflow occlusion method for hepatic radiofrequency ablation.

BACKGROUND/AIMS: Various strategies to expand the ablation zone have been attempted using hepatic radiofrequency ablation (RFA). The optimal strategy, however, is unknown. We compared hepatic RFA with an internally cooled wet (ICW) electrode and vascular inflow occlusion. METHODS: EIGHT DOGS WERE ASSIGNED TO ONE OF THREE GROUPS: only RFA using an internally cooled electrode (group A), RFA using an ICW electrode (group B), and RFA using an internally cooled electrode with the Pringle maneuver (group C). The ablation zone diameters were measured on the gross specimens, and the volume of the ablation zone was calculated. RESULTS: The ablation zone volume was greatest in group B (1.82±1.23 cm(3)), followed by group C (1.22±0.47 cm(3)), and then group A (0.48±0.33 cm(3)). The volumes for group B were significantly larger than the volumes for group A (p=0.030). There was no significant difference in the volumes between groups A and C (p=0.079) and between groups B and C (p=0.827). CONCLUSIONS: Both the usage of an ICW electrode and hepatic vascular occlusion effectively expanded the ablation zone. The use of an ICW electrode induced a larger ablation zone with easy handling compared with using hepatic vascular occlusion, although this difference was not statistically significant.

Intrahepatic portosystemic venous shunt: successful embolization using the Amplatzer Vascular Plug II.

A 67-year-old woman presented with memory impairment and behavioral changes. Brain MRI indicated hepatic encephalopathy. Abdominal CT scans revealed an intrahepatic portosystemic venous shunt that consisted of two shunt tracts to the aneurysmal sac that communicated directly with the right hepatic vein. The large tract was successfully occluded by embolization using the newly available AMPLATZERTM Vascular Plug II and the small tract was occluded by using coils. The patient's symptoms disappeared after shunt closure and she remained free of recurrence at the 3-month follow-up evaluation.

Iatrogenic left internal mammary artery to great cardiac vein anastomosis treated with coil embolization.

Inadvertent left internal mammary artery (LIMA)-great cardiac vein (GCV) anastomosis is a rare complication of coronary artery bypass graft surgery. Patients with iatrogenic aortocoronary fistula (ACF) were usually treated surgical repair, percutaneous embolic occlusion with coil or balloon. We report a case of iatrogenic LIMA to GCV anastomosis successfully treated with coil embolization and protected left main coronary intervention through the percutaneous transfemoral approach.

Incidental detection of interstitial pregnancy on CT imaging.

Ectopic pregnancy is a potentially life-threatening condition. Detection of ectopic pregnancy on CT images is rare. In this case, we describe the CT findings of interstitial pregnancy both before and after rupture. If CT images demonstrate the presence of a strong enhancing ring-like mass in the pelvis, ectopic pregnancy should be considered.