Extensive Aortic Stent Graft Coverage for Thoracoabdominal Aortic Aneurysm is Associated With Hemorrhagic Complications Induced by Disseminated Intravascular Coagulation.

BACKGROUND: Hybrid endovascular repair for thoracoabdominal aortic aneurysm (TAAA) is a less invasive alternative treatment than conventional open repair. However, disseminated intravascular coagulation (DIC) and hemorrhagic complications can occur postoperatively. We investigated risk factors for hemorrhagic complications after hybrid endovascular TAAA repair. METHODS: Sixty-one patients who underwent elective hybrid endovascular TAAA repair between 2007 and 2020 were included. Laboratory data before and after placing stent graft were collected, and DIC was diagnosed using a scoring system established by the Japanese Association for Acute Medicine. The length of the stent graft used to cover the aorta was defined as the aortic coverage length, which was measured using the first postoperative computed tomography image. Predictors of unexpected hemorrhagic complications were evaluated. RESULTS: Postoperative thrombocytopenia was observed in 57 (93%) patients, and their platelet count decreased significantly after stent graft placement (14.3 [9.5-18.0] vs. 8.2 [5.4-10.9] × 104/µL, P < 0.001). Fifteen (25%) and 45 patients (74%) were diagnosed with DIC before and after stent graft placement, respectively. Hemorrhagic complications were observed in 21 patients (34%). Multivariate logistic regression analysis revealed that aortic coverage length was an independent risk factor for hemorrhagic complications (odds ratio 1.441/50 mm increase; 95% confidence interval, 1.041-1.994, P = 0.027). The cutoff value for aortic coverage length obtained from the receiver operating characteristic curve (area under the curve = 0.72) was 304.4 mm (sensitivity 0.76, specificity 0.70). CONCLUSION: Aortic coverage length is a risk factor for hemorrhagic complications. Patients undergoing extensive aortic coverage greater than 304 mm should be closely monitored.

Vessel Occlusion using Hydrogel-Coated versus Nonhydrogel Embolization Coils in Peripheral Arterial Applications: A Prospective, Multicenter, Randomized Trial.

PURPOSE: To evaluate the safety and effectiveness of hydrogel-coated coils for vessel occlusion in the body trunk. MATERIALS AND METHODS: A total of 77 patients with various peripheral vascular lesions, treatable by embolization with coils, were randomized (hydrogel group, n = 38; nonhydrogel group, n = 39). In the hydrogel group, embolization of the target vessel was conducted using 0.018-inch hydrogel-coated coils (AZUR 18; Terumo Medical Corporation, Tokyo, Japan) with or without bare platinum coils. The nonhydrogel group received both bare platinum coils and fibered coils without the use of hydrogel-coated coils. RESULTS: Complete target vessel occlusion was accomplished in 36 patients in the hydrogel group and 37 patients in the nonhydrogel group. No major adverse events were observed in either group. The median number of coils/vessel diameter and the median total coil length/vessel diameter were significantly larger in the nonhydrogel group than in the hydrogel group (P = .005 and P = .004, respectively). The median embolization length was significantly longer in the nonhydrogel group (31.95 mm) than in the hydrogel group (23.43 mm) (P = .002). If no expansion was assumed, the median packing density in the hydrogel group was 44.9%, which was similar to that in the nonhydrogel group (46.5%) (P = .79). With full expansion assumed, the median packing density in the hydrogel group was 125.7%. CONCLUSIONS: Hydrogel-coated coils can be safely used for peripheral vascular coil embolization, and hydrogel-coated and conventional coils in combination allow for a shorter embolization segment and shorter coil length.

Management of Renal Arteries in Conjunction with Thoracic Endovascular Aortic Repair for Complicated Stanford Type B Aortic Dissection: The Japanese Multicenter Study (J-Predictive Study).

Background Management of abdominal branches associated with Stanford type B aortic dissection is controversial without definite criteria for therapy after thoracic endovascular aortic repair (TEVAR). This is in part due to lack of data on natural history related to branch vessels and their relationship with the dissection flap, true lumen, and false lumen. Purpose To investigate the natural history of abdominal branches after TEVAR for type B aortic dissection and the relationship between renal artery anatomy and renal volume as a surrogate measure of perfusion. Materials and Methods This study included patients who underwent TEVAR for complicated type B dissection from January 2012 to March 2017 at 20 centers. Abdominal aortic branches were classified with following features: patency, branch vessel origin, and presence of extension of the aortic dissection into a branch (pattern 1, supplied by the true lumen without branch dissection; pattern 2, supplied by the true lumen with branch dissection, etc). The branch artery patterns before TEVAR were compared with those of the last follow-up CT (mean interval, 19.7 months) for spontaneous healing. Patients with one kidney supplied by pattern 1 and the other kidney by a different pattern were identified, and kidney volumes over the course were compared by using a simple linear regression model. Results Two hundred nine patients (mean age ± standard deviation, 66 years ± 13; 165 men and 44 women; median follow-up, 18 months) were included. Four hundred fifty-nine abdominal branches at the last follow-up were evaluable. Spontaneous healing of the dissected branch occurred in 63% (64 of 102) of pattern 2 branches. Regarding the other patterns, 6.5% (six of 93) of branches achieved spontaneous healing. In 79 patients, renal volumes decreased in kidneys with pattern 2 branches with more than 50% stenosis and branches supplied by the aortic false lumen (patterns 3 and 4) compared with contralateral kidneys supplied by pattern 1 (pattern 2 vs pattern 1: -16% ± 16 vs 0.10% ± 11, P = .002; patterns 3 and 4 vs pattern 1: -13% ± 14 vs 8.5% ± 14, P = .004). Conclusion Spontaneous healing occurs more frequently in dissected branches arising from the true lumen than in other branch patterns. Renal artery branches supplied by the aortic false lumen or a persistently dissected artery with greater than 50% stenosis are associated with significantly greater kidney volume loss. © RSNA, 2019 Online supplemental material is available for this article.

Multicenter Analysis of Endovascular Aortic Arch In Situ Stent-Graft Fenestrations for Aortic Arch Pathologies.

BACKGROUND: In situ fenestration of aortic stent grafts for treatment of aortic arch aneurysms is a new option for endovascular aortic arch repair. So far, only few reports have shown perioperative and short-term results of in situ fenestrations for aortic arch diseases. We present the multicenter experience with the aortic arch in situ fenestration technique documented in the AARCHIF registry for treatment of aortic arch aneurysms or localized type A aortic dissections and analyzed perioperative outcome and midterm follow-up. METHODS: Patients with aortic arch pathologies treated by aortic arch in situ fenestration with proximal stent graft landing in aortic arch Ishimura zones 0 and 1 were included in the registry. Stent-graft in situ fenestrations were created using needles or radiofrequency or laser catheters and completed by implantation of covered connecting stent grafts. Single in situ fenestrations for the left subclavian artery (LSA) were excluded. RESULTS: Between 06/2009 and 03/2017, twenty-five patients were treated by in situ stent-graft fenestrations for aortic arch pathologies at 9 institutions in 7 different countries, 3 of them as bailout procedures for stent-graft malplacement. In situ fenestrations were performed for the brachiocephalic trunk (n = 20), the left common carotid artery (n = 21) and the LSA (n = 9). Technical success for intended in situ fenestrations was 94.0% (47/50), with additional supraaortic bypass procedures performed in 14 patients. Perioperative mortality occurred in 1 (4.0%) patient, treated as a bailout procedure and 3 (12.0%) perioperative strokes were observed. One proximal aortic stent-graft nonalignment and 4 type III endoleaks, 2 early and 2 late, required reeintervention. During follow-up (1-118 months), the diameter of aortic arch aneurysms decreased from 61.5 ± 4.1 mm to 48.4 ± 3.2 mm (P = 0.02) and, so far, 6 patients died from diseases unrelated to their aortic arch pathologies with a mean survival time of 79.5 months and 3 endovascular reinterventions for distal aortic expansion were performed. Cerebrovascular event (n = 4) was the most relevant prognostic factor for mortality during midterm follow-up (P = 0.003). CONCLUSIONS: The aortic arch in situ fenestration technique for endovascular aortic arch repair seems to be valuable treatment option for selected patients, although initial consideration of other treatment options is mandatory. Data about long-term durability are required.

Balloon-Occluded Retrograde Transvenous Obliteration for Isolated Gastric Varices Draining through Pericardiophrenic Vein without Gastrorenal or Gastrocaval Shunts.

Balloon-occluded retrograde transvenous obliteration (BRTO) is an effective and minimally invasive treatment for isolated gastric varices (GVs) that is usually performed through a gastrorenal shunt (GRS) or gastrocaval shunt (GCS). However, there are some cases in which GVs drain mainly into the left pericardiophrenic vein without an accessible GRS or GCS. This brief report presents four cases of GVs without a GRS/GCS treated by BRTO through the pericardiophrenic vein. BRTO was successfully performed with the use of flexible balloon catheters without any complications in all four patients, and the GVs were completely obliterated.

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture.

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

[Transaortic Thoracic Endovascular Aortic Repair Via Right Anterior Mini-thoracotomy;Report of a Case].

An 81-year-old man presented with ruptured thoracic aortic aneurysm under stable condition. He had been suffering from chronic obstructive pulmonary disease, chronic renal failure and rheumatoid arthritis. We performed hybrid thoracic endovascular aortic repair via right anterior mini-thoracotomy inserting a device through a conduit on the ascending aorta. The patient was discharged without aorta-related complications.

Shunted pouches of cavernous sinus dural AVFs: evaluation by 3D rotational angiography.

INTRODUCTION: The aims of this study were to evaluate the angioarchitecture of cavernous sinus dural arteriovenous fistulas (CSdAVFs), including the number and location of shunted pouches (SPs), and to evaluate whether the location and number of the SPs affect the outcomes of transvenous embolization of CSdAVFs. METHODS: Nineteen consecutive cases of CSdAVFs that underwent rotational angiography and transvenous embolization were reviewed. Multiplanar reconstruction images of rotational angiography and selective angiography were reviewed with particular interest in the SPs. Relationships of the locations and number of SPs with the results of transvenous embolization were statistically analyzed. RESULTS: All cases showed SPs, with numbers ranging from 1 to 4 (mean, 2.2). The location of the SPs was "posteromedial" in 16, "posterolateral" in 13, "lateral" in 6, and "medial" in 3 patients. Six cases showed posteromedial SPs alone, and three cases showed posterolateral SPs alone. The other 10 cases showed multiple locations of SPs. All cases were treated by transvenous embolization with sinus packing (n = 11) or selective embolization of the SP (n = 8). Complete occlusion of dAVF was obtained in 16 cases immediately after embolization. Locations of SPs and drainage types were significantly associated with the immediate angiographic results (p < 0.01). CONCLUSION: The SP of CSdAVFs is often multiple and is located posteriorly to the CS. The number and location of SPs affect immediate angiographic results of transvenous embolization.

Double coaxial microcatheter technique for transarterial aneurysm sac embolization of type II endoleaks after endovascular abdominal aortic repair.

PURPOSE: To evaluate the feasibility and efficacy of transarterial sac embolization with a mixture of N-butyl cyanoacrylate and ethiodized oil (Lipiodol; Guerbet Japan, Tokyo, Japan) (NBCA-LPD) for type II endoleaks after endovascular aortic repair (EVAR) using a double coaxial microcatheter technique. MATERIALS AND METHODS: A retrospective review was performed of 20 consecutive cases of type II endoleaks treated by transarterial embolization using the technique from August 2010 to June 2013. The treatment indication was persistent type II endoleak over 6 months after EVAR associated with aneurysm expansion ≥ 5 mm in maximum diameter. A 1.9-F nontapered microcatheter was advanced to the aneurysmal sac through a 2.7-F microcatheter, which was coaxially introduced through a catheter. The endpoint of the procedure was intrasaccular filling with NBCA-LPD and occlusion of the feeder of the type II endoleak. The technical success rate was defined as success in transarterial intrasaccular approach followed by embolization of the intrasaccular channel and inflow arteries. Clinical success was defined as aneurysmal sac shrinkage or stabilization (freedom from sac expansion > 5 mm in maximum diameter). RESULTS: Technical success was achieved in 18 of 20 cases. During a mean follow-up period of 18.5 months, complete sac occlusion was observed in 13 cases (65%). Clinical success was achieved in 16 cases (80%). No serious complications were observed. CONCLUSIONS: The transarterial intrasaccular approach with a double coaxial microcatheter technique can be successfully performed in most cases, and transarterial aneurysm sac embolization using NBCA-LPD has been proven to be feasible.

Mid-term outcomes of physician-modified endograft therapy for complex aortic aneurysms.

OBJECTIVES: Our goal was to evaluate early and mid-term outcomes of physician-modified endografting for pararenal and thoraco-abdominal aortic aneurysms from 10 Japanese aortic centres. METHODS: From January 2012 to March 2022, a total of 121 consecutive adult patients who underwent physician-modified endografting for pararenal and thoraco-abdominal aortic aneurysms were enrolled. We analysed early and mid-term postoperative outcomes, including postoperative complications and mortality. RESULTS: The pararenal and thoraco-abdominal aortic aneurysm groups included 62 (51.2%) and 59 (48.8%) patients, respectively. The overall in-hospital mortality rate was 5.8% (n = 7), with mortality rates of 3.2% (n = 2) and 8.5% (n = 5) in pararenal and thoraco-abdominal aortic aneurysm groups, respectively (P = 0.225). Type IIIc endoleaks occurred postoperatively in 18 patients (14.9%), with a significantly higher incidence (P = 0.033) in the thoraco-abdominal aortic aneurysm group (22.0%, n = 13) than in the other group (8.1%, n = 5). Major adverse events occurred in 7 (11.3%) and 14 (23.7%) patients in pararenal and thoraco-abdominal aortic aneurysm groups (P = 0.074), respectively. The mean follow-up period was 24.2 months. At the 3-year mark, both groups differed significantly in freedom from all-cause mortality (83.3% and 54.1%, P = 0.004), target aneurysm-related mortality (96.8% and 82.7%, P = 0.013) and any reintervention (89.3% and 65.6%, P = 0.002). Univariate and multivariate regression analyses demonstrated that ruptures, thoraco-abdominal aortic aneurysms and postoperative type IIIc endoleaks were associated with an increased risk of all-cause mortality. CONCLUSIONS: The mid-term outcomes of physician-modified endografting for pararenal and thoraco-abdominal aortic aneurysms were clinically acceptable and comparable with those in other recently published studies. Notably, pararenal and thoraco-abdominal aortic aneurysms represent distinct pathological entities with different postoperative outcomes.

Unenhanced magnetic resonance angiography with time-spatial labeling inversion pulse for evaluating visceral artery aneurysms after endosaccular packing with detachable coils: preliminary results.

The aim of this brief report is to compare unenhanced magnetic resonance (MR) angiography with time-spatial labeling inversion pulse (Time-SLIP) with conventional digital subtraction angiography (DSA) in assessing degree of saccular visceral artery aneurysm (VAA) occlusion after endosaccular packing with detachable coils. Eight patients with VAAs (five renal and three splenic artery aneurysms) were enrolled in this study. VAA occlusion rates based on Time-SLIP MR angiography were complete occlusion in four patients, neck remnants in three patients, and body filling in one patient. These findings corresponded with the DSA findings.

Multidetector CT anatomy of drainage routes of gastric varices: a pictorial review.

Most gastric varices arise at hepatofugal collateral pathways and drain into the systemic vein through one or both of two different types of portosystemic collateral drainage systems: the gastroesophageal (azygous) venous system and the gastrophrenic venous system. The gastroesophageal venous system consists of gastric varices contiguous with esophageal varices, paraesophageal varices, and the azygos vein, which terminates into the superior vena cava. Gastric varices draining through the gastroesophageal venous system can be treated with endoscopic techniques or creation of a transjugular intrahepatic portosystemic shunt. The gastrophrenic venous system consists of the gastric varices and the left inferior phrenic vein (IPV), which terminates into the left renal vein or the inferior vena cava. The left IPV has abundant anastomoses with peridiaphragmatic and retroperitoneal veins, and these anastomoses can function as drainage pathways from gastric varices. Balloon-occluded retrograde transvenous obliteration is a preferred treatment option for this type of gastric varix. Occasionally, gastric varices can form at the hepatopetal collateral pathway that develops secondary to localized portal hypertension caused by splenic vein occlusion. Splenectomy is often required for the treatment of this type of gastric varix. Multidetector computed tomography permits comprehensive evaluation of these venous drainage systems. Familiarity with and assessment of these draining routes of gastric varices are important for selecting treatment options and interventional techniques.

Selective transarterial embolization with n-butyl-2-cyanoacrylate for the treatment of arterial hemorrhage after third molar extraction.

INTRODUCTION: Comprehensive reports concerning selective embolization for arterial bleeding from third molar removal have not been published. We analyzed cases of arterial bleeding from third molar extraction that required transarterial embolization, and we demonstrate representative cases. METHODS: Five consecutive patients (three men and two women, aged 24 to 37 years) who underwent transarterial embolization at our institution were included in this study. Four of them showed postoperative bleeding after lower third molar removal, and one suffered bleeding after upper third molar extraction. The period of time from extraction to embolization varied from 5 h to 5 weeks. RESULTS: Angiography revealed pseudoaneurysms at the inferior alveolar artery in four cases and at the superior alveolar artery in one case. The pseudoaneurysms were selectively embolized using 25-33 % n-butyl-2-cyanoacrylate (NBCA)-lipiodol. All of the cases showed good results angiographically and clinically. Transit hypoesthesia at the region of the mental nerve was observed in one patient. CONCLUSION: Selective transarterial embolization is an effective technique for arterial bleeding from third molar removal when it is difficult to obtain hemostasis by dental procedures. Injection of NBCA can be useful when the alveolar artery is too small to embolize with coils.

Leiomyosarcoma Presenting as Rupture With a Type II Endoleak After Thoracic Endovascular Aortic Repair.

Endovascular stent-graft therapy is a commonly performed procedure for aortic lesions worldwide and complications unique to stent grafts, such as postoperative endoleaks, are well known. However, as this treatment modality becomes more popular, physicians should carefully monitor for other unexpected complications, which may not always be related to the graft. This study presents a case of leiomyosarcoma of the aorta that developed during follow-up for a type II endoleak (T2EL) after thoracic endovascular aortic repair. The presence of the T2EL hindered the diagnosis of the sarcoma at an early stage. These findings suggest that an apparent aneurysm that grows suddenly during follow-up after stent grafting should raise the index of suspicion for a neoplasm as well as an endoleak.

Anatomic features and retrograde transvenous obliteration of duodenal varices associated with mesocaval collateral pathway.

PURPOSE: To evaluate techniques and efficacy of retrograde transvenous obliteration for the treatment of duodenal varices associated with mesocaval collateral pathway. MATERIALS AND METHODS: Six consecutive cases of large/growing or ruptured duodenal varices treated by retrograde transvenous obliteration were retrospectively reviewed. Selective balloon-occluded retrograde transvenous obliteration (B-RTO) with 5% ethanolamine oleate (EO) was performed in all cases. When EO could not be sufficiently stagnated in the varices, additional/alternative techniques were performed, including coil embolization of afferent vein or intravariceal injection of n-butyl-2-cyanoacrylate (NBCA). Clinical findings, anatomic features of duodenal varices, obliteration techniques, complications, posttherapeutic computed tomography (CT) findings, and follow-up endoscopic findings were investigated. RESULTS: All duodenal varices were located at the second/third junction of the duodenum and were fed by single (n = 1) or multiple (n = 5) pancreaticoduodenal veins. One varix fed by a single afferent vein was successfully treated by simple selective B-RTO technique alone. The other five cases required coil embolization of afferent vein (n = 1) or intravariceal injection of NBCA (n = 4) because sclerosant was not sufficiently stagnated in the varices. CT 1 week after the procedure showed complete occlusion of the varices in all cases. A duodenal ulcer at the variceal site developed in one patient and was successfully treated by medication. Follow-up endoscopy showed disappearance of varices in all cases, and no recurrence was observed during follow-up. CONCLUSIONS: Retrograde transvenous obliteration is an effective technique for the treatment of duodenal varices. However, additional/alternative techniques are required for successful treatment because of the complex anatomic features of duodenal varices.

Comparison of Outcomes and Complications Among Patients with Different Indications of Acute/Subacute Complicated Stanford Type B Aortic Dissection Treated by TEVAR: Data from the JaPanese REtrospective multicenter stuDy of ThoracIc Endovascular Aortic Repair for Complicated Type B Aortic Dissection (J-Predictive Study).

PURPOSE: To investigate the relationships between indications for thoracic endovascular aortic repair for acute/subacute complicated Stanford type B aortic dissection and clinical outcomes, and complications specific to thoracic endovascular aortic repair. MATERIAL AND METHODS: The J-predictive study retrospectively collected data of patients treated with thoracic endovascular aortic repair for complicated Stanford type B aortic dissection at 20 institutions from January 2012 to March 2017. From the database, those treated for acute/subacute complicated Stanford type B aortic dissection were extracted (n = 118; 96 men; average age, 66.1 years; standard deviation, ± 13) and classified into groups 1, 2, and 3 according to thoracic endovascular aortic repair indications (rupture, superior mesenteric artery malperfusion, and renal or lower extremity malperfusion, respectively). Primary and secondary measures were mortality (overall and aortic-related) and complications related to thoracic endovascular aortic repair, respectively. For each outcome, the risks of being in groups 1 and 2 were statistically compared with that of being in group 3 as a control using Fisher's exact test. RESULTS: Mortality rate (odds ratio, 5.22; 95% confidence interval [CI], 1.33-20.53) and prevalence of paraparesis/paraplegia (odds ratio, 30.46; confidence interval, 1.71-541.77) were higher in group 1 than in group 3. Compared to group 3, group 2 showed no statistically significant differences in mortality or complications related to thoracic endovascular aortic repair. CONCLUSIONS: Rupture as an indication for thoracic endovascular aortic repair for type B aortic dissection was more likely to result in worse mortality and high prevalence of spinal cord ischemia. LEVEL OF EVIDENCE: Level 4, Case series.

Endovascular aortic arch reconstruction using in situ stent-graft fenestration in the brachiocephalic artery.

A patient who had previously undergone retrosternal gastric tube reconstruction for esophageal cancer presented with an aortic arch aneurysm. The patient was treated with endovascular stent-graft placement without median sternotomy, followed by revascularization of the brachiocephalic trunk using percutaneous in situ graft fenestration. A 9-month follow-up examination revealed marked regression of the aneurysm with patency of the stent-graft, without any complications. This in situ fenestration technique may extend the limits of thoracic endovascular therapy for patients who are unsuitable for sternotomy or aortic side-clamping.

Dual-energy (spectral) CT: applications in abdominal imaging.

Dual-energy imaging is a promising new development in computed tomography (CT) that has the potential to improve lesion detection and characterization beyond levels currently achievable with conventional CT techniques. In dual-energy CT (DECT), the simultaneous use of two different energy settings allows the differentiation of materials on the basis of their energy-related attenuation characteristics (material density). The datasets obtained with DECT can be used to reconstruct virtual unenhanced images as well as iodinated contrast material-enhanced material density images, obviating the standard two-phase (unenhanced and contrast-enhanced) scanning protocol and thus helping minimize the radiation dose received by the patient. Single-source DECT, which is performed with rapid alternation between two energy levels, can also generate computed monochromatic images, which are less vulnerable to artifacts such as beam hardening and pseudoenhancement and provide a higher contrast-to-noise ratio than polychromatic images produced by conventional CT. Familiarity with the capabilities of DECT may help radiologists improve their diagnostic performance.

Internal hernias after abdominal surgeries: MDCT features.

As less-invasive treatments for small bowel obstruction, such as laparoscopic surgery or small incision therapy, have become common, there is a growing demand for preoperative assessment of the cause and location of the small bowel obstruction. Thus, the role of computed tomography (CT) in the evaluation of small bowel obstruction is expanding. CT imaging of internal hernias (IHs) has been extensively described and is well established; however, CT imaging of IH after abdominal surgeries is not well recognized because of their anatomical complexity. The aims of this pictorial review are (1) to evaluate the causes of internal IHs in relation to previous abdominal surgery (e.g., IH associated with Roux-en-Y reconstruction, Billroth II reconstruction, peritoneal adhesive band, perineal hernia, and IH after gynecological procedures), (2) to demonstrate the spectrum of imaging findings on multidetector CT (MDCT), and (3) explain the key features for CT diagnosis of IHs related to previous surgical procedures, with emphasis on the multi-planar reformation (MPR) image. We also demonstrate the dynamic changes in the progression of mesenteric strangulation revealed by CT. Understanding the imaging appearance on MDCT can help radiologists guide therapy for patients with a small bowel obstruction after abdominal surgery.