Dual-phase 3D MDCT angiography for evaluation of the liver before hepatic resection

Detection of hepatocellular carcinoma feeding vessels: MDCT angiography with 3D reconstruction versus digital subtraction angiography

BACKGROUND

Accurate detection of Hepatocellular carcinoma (HCC) feeding vessels during transcatheter arterial chemoembolization (TACE) is important for an effective treatment, while limiting non-target embolization. This study aimed to investigate the feasibility and accuracy of pre-TACE three dimensional (3D) CT angiography for tumor-feeding vessels detection compared to DSA.

METHODS

Sixty-nine consecutive patients referred for TACE from May 2022 to May 2023 were included. (3D) CT images were reconstructed from the pre-TACE diagnostic multiphasic contrast enhanced CT images and compared with non-selective digital subtraction angiography (DSA) images obtained during TACE for detection of HCC feeding vessels. A "Ground truth" made by consensus between observers after reviewing all available pre-TACE CT images, and DSA and CBCT images during TACE to detect the true feeding vessels was the gold standard. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), accuracy and ROC curve with AUC were calculated for each modality and compared.

RESULTS

A total of 136 active HCCs were detected in the 69 consecutive patients included in the study. 185 feeding arteries were detected by 3D CT and DSA and included in the analysis. 3D CT detection of feeding arteries revealed mean sensitivity, specificity, PPV, NPV and accuracy of 91%, 71%, 98%, 36%, and 90%, respectively, with mean AUC = 0.81. DSA detection of feeding arteries revealed mean sensitivity, specificity, PPV, NPV, and accuracy of 80%, 58%, 96.5%, 16.5% and 78%, respectively, with mean AUC = 0.69.

CONCLUSIONS

Pre-TACE 3D CT angiography has shown promise in improving the detection of HCC feeding vessels compared to DSA. However, further studies are required to confirm these findings across different clinical settings and patient populations.

TRIAL REGISTRATION

This study was prospectively registered at Clinicaltrials.gov with ID NCT05304572; Date of registration: 2-4-2022.

Two novel hepatic arterial variations in a living liver donor detected by multidetector computed tomography angiography

PURPOSE

Considering that the knowledge of variations in the hepatic vascular structure is essential for hepatic surgery and liver transplantation, we aimed to present a rare case of the anatomic variation of arterial blood supply to the liver to help prevent complications and choose suitable donors.

METHODS

We present a novel variant in this case report (living liver donor), an accessory right hepatic artery (supplying segment 6) originating from the dorsal pancreatic artery and a middle hepatic artery (supplying segment 4) arising from the pancreaticoduodenal artery (first branch of the gastroduodenal artery). Preoperative diagnosis was made using computed tomography angiography (CTA) with multiplanar reformate (MPR) images, curved planar reformate (CPR), maximum intensity projection (MIP) images and three-dimensional volume renderings (3D VR).

RESULTS

To the best of our knowledge, this is the first case in the English literature describing this type of variation. A search for new donors began since the living liver donor was not suitable due to the very thin segment 4 artery, posing potential risks for the donor and the thin segment 6 artery being a complicating factor for anastomosis.

CONCLUSIONS

The preoperative knowledge of liver blood supply has great importance in planning surgery and transplantation. CTA, reformate and reconstruction techniques allow for the evaluation of difficult and complex anatomic variations.

3D Vessel Image Reconstruction by MDCT for Surgical Indication and Timing of Strangulating Small Bowel Obstructions

BACKGROUND

Patients with strangulating small bowel obstructions (SBOs) can rapidly deteriorate, in condition; therefore, immediate and appropriate diagnosis is required. However, some cases of SBO are difficult to diagnose using axial computed tomography (CT) images alone. The impact of 3D vessel imaging for the diagnosis, surgical indication, and timing of strangulating SBOs was investigated, prospectively.

METHODS

Clinical data were collected for 111 strangulating SBOs and 48 simple SBOs from patients receiving surgical interventions from January 2009 to March 2018. The accuracy of preoperative diagnoses for the type of SBO was evaluated. Among 159 patients, 27 underwent contrast-enhanced CT imaging as well as prospectively reconstructed 3D vessel imaging of the superior mesenteric artery, vein, and branches. The concordance rate of operative findings and preoperative diagnoses of the type of SBO were compared between axial CT imaging alone and combination of axial and 3D vessel imaging.

RESULTS

Overall concordance rate of diagnosis for the type of SBO by axial imaging was 93.1% and that of strangulating and simple SBOs was 92.8% and 93.8%, respectively. Combined axial and 3D vessel imaging resulted in 100% accuracy of preoperative diagnoses for both types of SBO. In addition, abnormalities could be classified from 3D vessel images as central twists or peripheral twists, and deteriorated vascular flow could also be detected.

CONCLUSIONS

The combination of axial imaging and 3D vessel imaging can be used to accurately diagnose SBOs, and this imaging technique may be useful for determining the surgical indication and suitable timing of strangulating SBOs.

Aberrant left gastric vein is associated with hepatic artery variations

OBJECTIVE

To investigate the imaging findings and hepatic artery variations encountered in patients with aberrant left gastric vein (ALGV).

METHODS

A retrospective database search between January 2014 and November 2018 was carried for ALGV. The course and types (1-3) of ALGV, the presence of associated liver lesions, and coexistence of hepatic artery variations were reviewed on CT images.

RESULTS

A total of 32 patients (22 men, 68.7%) with a mean age of 52.5 years (range 22-76 years) were found to have ALGV. The prevalence of ALGV was 0.073%. The most frequent type of ALGV was type 1 (n = 22, 68.7%), followed by type 3 (n = 7, 21.8%) and type 2 (n = 3, 9.3%). We noticed mild-to-severe parenchymal hyperdensity at the posterior aspect of segments II and III in patients with type 1 (n = 20/22) and type 2 (n = 2/3) ALGV consistent with fat sparing due to third inflow effect. Two out of seven patients with type 3 ALGV had main portal vein thrombosis; however, the presence of ALGV maintained left portal vein flow in these patients. Twelve (37.5%) patients had accompanying hepatic artery variation. Left hepatic and right hepatic artery variations were detected in 8 (25%) and 2 (6.25%) of the patients, respectively. In 2 patients, Michels type IV variation was detected.

CONCLUSION

Aberrant left gastric vein is associated with hepatic artery variations, which can be important for preoperative and pretransplant planning.

Aberrant left hepatic arteries arising from left gastric arteries and their clinical importance

BACKGROUND

The Aberrant Left Hepatic Artery (ALHA) is replaced when it does not originate from the hepatic artery proper and it is the only supply to that part of the liver, while an accessory artery coexists with a normal artery. The aim of this systematic review is to evaluate the incidence of ALHAs including the one arising from the Left Gastric Artery, also named Hyrtl's artery.

METHODS

A literature search in PubMed, SCOPUS, WOS and Google Scholar was performed. The risk of bias was assessed by means of the AQUA tool. The main outcome was the prevalence of ALHA. Secondary outcomes were the prevalence of the accessory and replaced left hepatic arteries. A subgroup analysis was conducted by geographic region and type of evaluation.

RESULTS

This review included 57 studies, with a total of 19,284 patients. The majority of the studies involved the use of radiological techniques -especially Angio-CT-and were performed in Asia. The overall risk of bias was moderate. The overall prevalence of the ALHA was 13.52%; the overall prevalence was 8.26% for the Replaced ALHA and 5.55% for the Accessory ALHA. In the 18 studies that employed Michels' classification, Type II had the lowest prevalence (0.36%) and Type VII the highest prevalence (6.62%).

DISCUSSION

Some of the studies included did not distinguish between the ''replaced'' and ''accessory'' ALHA (34.25%). Some surgical dissection techniques proved insufficient for the localization of other hepatic arteries. These results suggest that an accurate preoperative radiological evaluation is needed to localize replaced arteries.

Vascular Anomalies of the Extrahepatic Artery as a Predictable Risk Factor for Complications After Liver Transplant

OBJECTIVES

Vascular variations of the extrahepatic artery occur in up to 50% of the population. Exact knowledge of any anomalies is of great significance in hepatobiliary surgery to avoid perioperative complications. In fact, in liver transplant, vascular complications are rare but have a major impact on graft function and survival. This study evaluated variations of the extrahepatic artery in donors and recipients as risk factors for vascular complications after liver transplant.

MATERIALS AND METHODS

From January 2010 until June 2015, 469 liver transplant procedures were performed at our institution. We included 323 patients in our retrospective analysis after exclusion of retransplants, split-livertransplants, and pediatric patients. We analyzed the impact of anatomic variations of recipients and donors on postoperative vascular complications and organ and patient survival.

RESULTS

Of total study recipients, 71.2% had a normal vascular supply according to Michel classification I. However, these patients developed significantly more vascular complications (25.65%) than those with vascular anomalies (15.05%), especially showing higher incidence of arterial stenosis (8.26% vs 2.15%). In contrast, vascular variations in donors and the need for a vascular reconstruction of the graft led to significantly higher mortality (26.76% vs 15.48%). An abnormality of the graft did not influence incidence of postoperative complications or graft survival.

CONCLUSIONS

Unexpectedly, recipients with variations of the hepatic artery and grafts with an abnormal arterial supply did not show higher rates of com-plications or mortality. Only vascular reconstruction of the graft before transplant raised the mortality of recipients.

Surgical Anatomy of the Superior Mesenteric Vessels Related to Pancreaticoduodenectomy: a Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Mesopancreas dissection with central vascular ligation and the superior mesenteric artery (SMA)-first approach represent the cornerstone of current principles for radical resection for pancreatic head cancer. The surgeon dissecting around the SMV and SMA should be aware regarding the anatomical variants in this area. The aims of this systematic review and meta-analysis are to detail the surgical anatomy of the superior mesenteric vessels and to propose a standardized terminology with impact in pancreatic cancer surgery.

METHODS

We conducted a systematic search to identify all published studies in PubMed/MEDLINE and Google Scholar databases from their inception up to March 2017.

RESULTS

Seventy-eight studies, involving a total of 18,369 specimens, were included. The prevalence of the mesenteric-celiac trunk, replaced/accessory right hepatic artery (RRHA), common hepatic artery, and SMV inversion was 2.8, 13.2, 2.6, and 4.1%, respectively. The inferior pancreaticoduodenal artery has its origin into the first jejunal artery, SMA, and RRHA, in 58.7, 35.8, and 1.2% of cases, respectively. The SMV lacks a common trunk in 7.5% of cases. The first jejunal vein has a trajectory posterior to the SMA in 71.8% of cases. The left gastric vein drains into the portal vein in 58%, in splenic vein (SV) in 35.6%, and into the SV-PV confluence in 5.8% of cases.

CONCLUSIONS

Complex pancreaticoduodenal resections require detailed knowledge of the superior mesenteric artery and vein, which is significantly different from the one presented in the classical textbooks of surgery. We are proposing the concept of the first jejunopancreatic vein which impacts the current oncological principles of pancreatic head cancer resection.

The Main Anatomic Variations of the Hepatic Artery and Their Importance in Surgical Practice: Review of the Literature

Anatomical variations of the hepatic artery are important in the planning and performance of abdominal surgical procedures. Normal hepatic anatomy occurs in approximately 80% of cases, for the remaining 20% multiple variations have been described. The purpose of this study was to review the existing literature on the hepatic anatomy and to stress out its importance in surgical practice. Two main databases were searched for eligible articles during the period 2000 - 2015, and results concerning more than 19,000 patients were included in the study. The most common variation was the replaced right hepatic artery (type III according to Michels classification) which is the chief source of blood supply to the bile duct.

Right hepatic artery from splenic artery: the four-leaf clover of hepatic surgery

The anatomy of hepatic arteries is one of the most variable. Accurate awareness of all the possible anatomic variations is crucial in the upper GI surgery and especially in liver and pancreas transplantation. The most frequent anatomical variants are: a replaced or accessory right hepatic artery (RHA) from the superior mesenteric artery (6.3-21 %), a replaced or accessory left hepatic artery (LHA) from the left gastric artery (LGA) (3-18 %) or a combination of these two variants (up to 7.4 %). Herein, we describe the case of a 67-year-old cadaveric organ donor who presented a RHA originating from the splenic artery (SA) associated with both a CHA originating from the celiac trunk (CT) and a LHA originating from the LGA.

Feasibility of MDCT angiography for determination of tumor-feeding vessels in chemoembolization of hepatocellular carcinoma

OBJECTIVE

To investigate the feasibility and accuracy of multidetector computed tomography (MDCT) angiography for assessment of subsegmental tumor-feeding vessels in transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

A total of 23 patients with 36 HCCs who underwent TACE during a 14-month period were enrolled. All patients underwent 3-phase dynamic MDCT within a month before TACE. Arterial phase MDCT images were retrospectively reformatted and analyzed for determination of single subsegmental tumor-feeding vessel using maximum intensity projection (MIP) and volume-rendering technique (VRT). Two radiologists independently assessed and scored the MIP and VRT images using 4-grade visual scores (grade 1, no depiction of tumor-feeding vessel; grade 2, indeterminate tumor-feeding vessel; grade 3, probable tumor-feeding vessel; and grade 4, good depiction of tumor-feeding vessel). The weighted kappa test was used to determine interobserver variability, and Wilcoxon signed rank test was used to differentiate visual scores of each technique. Results of digital subtraction angiography were defined as the criterion standard; therefore, assessment of subsegmental tumor-feeding vessel using MIP or VRT was compared with digital subtraction angiography, and the accuracy of each technique was calculated.

RESULTS

Interobserver agreement (weighted kappa, 0.746 on VRT and 0.806 on MIP) was substantial to almost perfect. The visual scores for MIP (mean, 3.64 for reviewer 1 and 3.5 for reviewer 2) were higher than those for VRT (mean, 2.11 for reviewer 1 and 2.22 for reviewer 2; P = 0.000). The accuracy for assessing subsegmental tumor-feeding vessel was 22.2% for VRT and 77.8% for MIP.

CONCLUSION

Multidetector CT angiography using MIP showed good imaging quality and high accuracy for determination of subsegmental tumor-feeding vessels.

Preoperative dual-phase 3D CT angiography assessment of the right hepatic artery before gastrectomy

PURPOSES

In the current study, we evaluated the efficacy of dual-phase three-dimensional (3D) CT angiography (CTA) in the assessment of the vascular anatomy, especially the right hepatic artery (RHA), before gastrectomy.

METHODS

The study initially included 714 consecutive patients being treated for gastric cancer. A dual-phase contrast-enhanced CT scan using 32-multi detector-row CT was performed for all patients.

RESULTS

Among the 714 patients, 3D CTA clearly identified anomalies with the RHA arising from the superior mesenteric artery (SMA) in 49 cases (6.9 %). In Michels' classification type IX, the common hepatic artery (CHA) originates only from the SMA. Such cases exhibit defective anatomy for the CHA in conjunction with the celiac-splenic artery system, resulting in direct exposure of the portal vein beneath the #8a lymph node station, which was retrospectively confirmed by video in laparoscopic gastrectomy cases. Fused images of both 3D angiography and venography were obtained, and could have predicted the risk preoperatively, and the surgical finding confirmed its usefulness.

CONCLUSION

Preoperative evaluations using 3D CTA can provide more accurate information about the vessel anatomy. The fused images from 3D CTA have the potential to reduce the intraoperative risks for injuries to critical vessel, such as the portal vein, during gastrectomy.

Three-dimensional images of liver tumours reconstructed by Gd-EOB-DTPA-enhanced MRI

The purpose of this study was to evaluate three-dimensional images of liver tumours obtained with gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-enhanced MRI (3D-EOB-MRI) in hepatic surgery. We conclude that 3D-EOB-MRI may be an alternative method for depicting liver tumours adjacent to the hepatic veins and portal branches, and may provide additional information for surgical planning.

Value of 64-slice spiral CT triple-phase enhanced scanning for preoperative evaluation of lymph node dissection in patients with gastric cancer

AIM: To analyze the value of 64-slice spiral computed tomography (CT) triple-phase enhanced scanning for preoperative evaluation of lymph node dissection in patients with gastric cancer.

METHODS: Thirty-eight patients with gastric cancer underwent preoperative 64-slice spiral CT triple-phase enhanced scanning to comprehend the anatomic distribution of the celiac trunk, its three branches and their tributaries (common hepatic artery, right hepatic artery, left hepatic artery, splenic artery, and left gastric artery) through volume rendering and three dimensional vascular imaging. The lymph nodes were detected using group orientation method, and N staging was performed to compare with postoperative pathological results.

RESULTS: Surgical results verified that 64-slice spiral CT triple-phase enhanced scanning through volume rendering and three dimensional vascular imaging had an accuracy rate of 100% in preoperative evaluation of the distribution of the celiac trunk, its three branches and their tributaries. Compared to postoperative pathological results, the accuracy rate was 92.1% (35/38) in evaluating perigastric lymph node metastasis, and 71.4% (5/7), 62.5% (5/8), 81.82% (9/11), 75% (6/8), 25% (1/4) and 68.42% (26/38) in preoperatively evaluating stages N0-N3b and N gastric cancer, respectively.

CONCLUSION: Preoperative 64-slice spiral CT triple-phase enhanced scanning is an objective way to assess the distribution of the celiac artery trunk and related tributaries in patients with gastric cancer, and it allows to reliably judge whether there is perigastric lymph node metastasis and can guide intraoperative lymph node dissection and reduce intraoperative injury to the artery.

Comparison of dynamic MRI at 3.0 T and MDCT of pancreatobiliary disease: evaluation with source, MPR, CPR, and MIP images for image quality and hepatic arterial and portal venous vessel conspicuity

PURPOSE

To compare contrast material-enhanced three-dimensional (3D) magnetic resonance imaging (MRI) at 3.0T and multidetector row computed tomography (MDCT) in the same patient with regard to image quality of pancreatobiliary disease and hepatic vascular conspicuity.

MATERIALS AND METHODS

This study enrolled 32 patients with pancreatobiliary disease who underwent both gadolinium-enhanced 3D dynamic MRI and multiphasic CT using 16-MDCT. Data analysis of image quality was performed by two radiologists based on source images, multiplanar reconstruction (MPR), curved planar reconstruction (CPR), and maximum intensity projection (MIP) reconstruction. Determination of image quality was based on a 4-point image quality rating scale.

RESULTS

The overall image quality of the MRI axial images was superior to that of the axial MDCT images. The MRI protocol yielded an average score of 3.8 points versus 3.5 for the CT imaging. No significant difference was found between 3.0T MRI and MDCT images in MPR or CPR image quality. Image quality for visualization of the distal intrahepatic segmental arteries was significantly improved using MDCT imaging. No significant difference was found between the MDCT and 3.0T MR in portal vein branch image quality.

CONCLUSION

High-resolution dynamic contrast-enhanced MR imaging at 3.0T is a comprehensive technique which provides high image quality in pancreatobiliary disease.

Anatomic variations of the hepatic arteries in 250 patients studied with 64-row CT angiography

The aim of our study was to determine the frequency of different hepatic arterial variants identified on abdominal CT angiography (CTA) with a 64-row CT system and a high resolution protocol. A total of 250 consecutive abdominal CTAs performed on a 64-row CT system were evaluated. Two radiologists in consensus analyzed arterial phase images; the anatomical findings were grouped according to Michels' classification. An anomalous arterial pattern was observed in 34% of the cases. The most common anomaly was Michels type III (9.2%), followed by types II and V (5.2%), type VI (4.0%), types IV, VII, and IX (2.0%), and type VIII (0.6%). No cases of type X were detected. Unclassified variations were observed in 3.3% of the cases. The new generation of 64-row MDCT allows optimal visualization of splanchnic vascular anomalies with a minimally invasive examination. This visualization is extended to those vessels with a small caliber and slow flow resulting in difficult recognition by classic angiographic studies. The knowledge of anomalous arterial patterns could be very useful in the preoperative planning of surgical and interventional liver procedures.

Contrast-enhanced hepatic magnetic resonance angiography at 3 T: does parallel imaging improve image quality?

PURPOSE

To evaluate whether hepatic magnetic resonance angiography (MRA) performed at 3 T and acquired with a parallel imaging acceleration factor of 2 provides satisfactory image quality and adequate contrast-to-noise, compared with an acquisition without parallel imaging.

MATERIALS AND METHODS

Ten volunteers underwent both a standard (A) and an experimental (B) MRA protocol. Both protocols used a gadoteridol dose of 20 mL injected at 2 mL/s in a 3-T magnetic resonance (MR) system. Protocol B was identical to protocol A, except protocol B was performed with a parallel imaging acceleration factor of 2. Contrast-to-noise ratios (CNRs) were calculated in the suprarenal abdominal aorta, the common hepatic artery, and the right and left hepatic arteries. The same 4 vessels were rated for quality of arterial visualization using a 5-point scale (1 = poor to 5 = excellent). The paired t test and Wilcoxon rank sum test were used for statistical analysis.

RESULTS

The CNRs and qualitative scores were higher in all 4 vessels using protocol B. Mean CNRs in the suprarenal abdominal aorta, common hepatic artery, and the right and left hepatic arteries were 31, 33, 28, and 22 for protocol A and 36, 40, 36, and 25 for protocol B, respectively (P < 0.05 except the left hepatic arteries [P = 0.35]). Mean qualitative scores of the same vessels were 4.3, 3.7, 3.1, and 2.9 using protocol A and 4.4, 3.8, 3.5, and 3.2 for protocol B, respectively (P > 0.44).

CONCLUSIONS

Parallel imaging performed in a 3-T MR system improves hepatic MRA both quantitatively and qualitatively.

High-Resolution Computed Tomographic Angiography/Computed Tomographic Cholangiography Image Fusion of the Hepatobiliary System

The 3-dimensional image was excellent as a result of the fast scanning and narrow collimation using multidetector computed tomography (CT); and the parallel escalation in the capabilities of the workstation allow the use of CT angiography/CT cholangiography image fusion. We demonstrated the feasibility of fusion images of the hepatobiliary system. We believe that fusion images are extremely valuable for applications such as preoperative planning for hepatic and bile duct resection.

Accessory Left Gastric Artery from Left Hepatic Artery Shown on MDCT and Conventional Angiography: Correlation with CT Hepatic Arteriography

OBJECTIVE

The objective of our study was to evaluate the diagnostic accuracy of MDCT and conventional angiography in the detection of an accessory left gastric artery using CT hepatic arteriography as the standard of reference.

MATERIALS AND METHODS

The study group consisted of 118 patients who underwent MDCT with a triple-phase liver protocol with a slice thickness of 5 mm, conventional angiography, and CT hepatic arteriography. The early-phase images of MDCT and conventional angiography were retrospectively reviewed. The presence or absence of an accessory left gastric artery was evaluated using CT hepatic arteriography as the standard of reference. The sensitivity, specificity, and accuracy of MDCT and conventional angiography were calculated.

RESULTS

CT hepatic arteriography revealed an accessory left gastric artery in 25 (21.2%) of 118 cases, including 15 proximal- and 10 distal-type accessory left gastric arteries. On MDCT, there were seven false-negative cases and one false-positive case. Six of the seven false-negative cases were a proximal-type accessory left gastric artery, and nine of 10 distal-type accessory left gastric arteries were correctly diagnosed using MDCT. The sensitivity, specificity, and accuracy of MDCT were 72.0%, 98.9%, and 93.2%, respectively. On conventional angiography, there were three false-negative and two false-positive cases, none of whom underwent selective left hepatic arteriography. Two of the three false-negative cases were the distal-type accessory left gastric artery, but eight of the 10 distal-type accessory left gastric arteries were correctly diagnosed. The sensitivity, specificity, and accuracy of conventional angiography were 88.0%, 97.8%, and 95.8%, respectively.

CONCLUSION

Approximately 70% of accessory left gastric arteries can be diagnosed at the early phase of MDCT even with a slice thickness of 5 mm.

THREE-DIMENSIONAL MULTISLICE HELICAL COMPUTED TOMOGRAPHY TECHNIQUES FOR CANINE EXTRA-HEPATIC PORTOSYSTEMIC SHUNT ASSESSMENT

The purpose of the present study was to investigate the feasibility and usefulness of three-dimensional (3D) multislice computed tomography (CT) angiography with maximum intensity projection (MIP) and volume rendering (VR) in six dogs with clinical and sonographic findings suggestive of portosystemic shunt. Furthermore, we aimed to estimate the diameter of the portal vein and shunt vessels. MIP and VR reconstructions were performed for each patient and the origin and insertion of all shunt vessels were detected. In addition, 3D reconstructions allowed excellent depiction of vascular morphology and topography. All diagnoses and vessel measurements were confirmed by surgery. 3D multidetector CT angiography is a promising, noninvasive, and accurate method of evaluating dogs with suspected portosystemic shunts.

Assessment of the abdominal aorta and its visceral branches by contrast-enhanced dynamic volumetric hepatic parallel magnetic resonance imaging: feasibility, reliability and accuracy

The purpose of this study was to evaluate a new three-dimensional gradient-echo (GRE) MR sequence performed with a parallel acquisition technique to shorten breath-hold times (parallel GRE MRI) in the detection of arterial variants and stenosis of the abdominal aorta and its visceral branches. A total of 102 patients underwent dynamic parallel GRE MRI, timed to the arterial phase by a test bolus (mean breath-hold time, 17 s). For both quantitative and qualitative analysis, the abdominal aorta and its visceral branches were divided into 13 arterial segments. In a subanalysis of 55/102 patients, the accuracy of parallel GRE MRI compared to MDCT in the detection arterial variants and stenosis was calculated for two independent readers. Mean SNRs and CNRs were 47.2 and 35.6, respectively. Image quality was rated good or excellent in 1,234/1,326 segments (93%). Hepatic and renal arterial variants were identified with an accuracy of 93 and 95%, respectively (reader 1) and 98 and 100%, respectively (reader 2). Both readers detected arterial stenosis with an accuracy of 98%. Interobserver agreement was good to excellent for the detection of hepatic (kappa=0.69) and renal (kappa=0.92) variants and for the diagnosis of stenosis (kappa=0.96). Dynamic three-dimensional parallel GRE MRI is feasible and allows a reliable and accurate diagnosis of arterial variants and stenosis of the abdominal aorta and its visceral branches in a short breath-hold-time.

Prospective intraindividual comparison between respiratory-triggered balanced steady-state free precession and breath-hold gradient-echo and time-of-flight magnetic resonance imaging for assessment of portal and hepatic veins

The purpose of this study was to compare respiratory-triggered balanced steady-state free precession (bSSFP) with breath-hold contrast-enhanced dynamic two-dimensional (2D) gradient-echo (GRE) and time-of-flight (TOF) magnetic resonance imaging (MRI) for portal and hepatic vein visualization and assessment of portal and hepatic venous variants. Sixty patients with liver disease underwent nonenhanced bSSFP and contrast-enhanced GRE, bSSFP, and TOF imaging. Contrast-to-noise ratios (CNRs) for portal and hepatic veins were measured. Two readers rated the quality of portal and hepatic vein visualization on a 5-point Likert scale. The diagnostic performance of each MRI series in the detection of portal and hepatic venous variants was assessed in 40/60 patients who also underwent contrast-enhanced multidetector-row computed tomography (MDCT). CNRs for portal and hepatic veins were highest on contrast-enhanced bSSFP images. Image quality of portal and hepatic veins was rated higher for nonenhanced bSSFP than for contrast-enhanced GRE (p<0.03) and TOF (p<0.003) and higher for contrast-enhanced than for nonenhanced bSSFP (p<0.003). Compared with MDCT, portal and hepatic venous variants were identified with an accuracy of 99% on bSSFP images, with an excellent interobserver agreement (kappa=0.97). Compared with MDCT, presence of surgically important portal and hepatic venous anatomical variants can be predicted with high accuracy on bSSFP images.

Confirmation of the posterior gastric artery using multi-detector row computed tomography

BACKGROUND

The blood supply of the stomach is well characterized. Although the posterior gastric artery (PGA) is the second most important artery supplying the upper third of the stomach, the main features and clinical importance of the PGA have not been established. The aim of this study was to use multi-detector row computed tomography (MD-CT) to investigate the features of the PGA with respect to its incidence, location and size, and to correlate the findings with clinical practice.

METHODS

In August 2004, 50 preoperative patients (33 men and 17 women) were evaluated prospectively by MD-CT. Informed consent for the present study was accepted at Kochi Medical School. The length of the PGA, from the root of the splenic artery, and the internal diameter of the PGA were examined. Correlations between body mass index (BMI) and the observed features of the PGA were investigated.

RESULTS

The PGA was recognized in all patients. In 49 (98%) patients, the PGA branched from the splenic artery. In 1 (2%) patient, the PGA originated from the root of the celiac trunk. The PGA was discernible for a length of 4.2-14.3 cm (mean, 9.1 cm) from the root of the splenic artery, and the internal diameter of the PGA was 0.5-2.1 mm (mean, 1.0 mm). BMI did not correlate with PGA length or internal diameter.

CONCLUSION

Our current study suggested that the anatomical and clinical features of the PGA can be shown by clinical methods, and that these features are useful in planning surgical treatment.

IV Contrast Selection for MDCT: Current Thoughts and Practice

OBJECTIVE

The purpose of this article is to review studies evaluating how contrast concentration affects MDCT of the body and to report IV contrast infusion protocols from MDCT angiography and MDCT of abdominal tumors.

CONCLUSION

Higher concentrations (350 mg I/mL or greater) may improve visualization of small abdominal arteries. However, preliminary data comparing 300 mg I/mL to higher concentrations for MDCT of hypervascular hepatocellular carcinoma and pancreatic cancer have shown that higher concentrations may not increase tumor conspicuity.

Multidetector Row CT of the Liver

CT has always played a major role in the imaging of the liver despite continuous challenge by ultrasound and MR imaging. Introduction of multidetector row CT technology has helped CT to excel in its already established indications and has expanded its capabilities by adding new clinical indications, such as CT angiography or liver perfusion. This article discusses the advantages of multidetector row CT scanners in liver imaging, examines the guidelines to improve image quality by optimizing scanning protocols and contrast administration strategies, and reviews the current and potential clinical applications.