Assessment of salivary gland tumors using MRI and CT: impact of experience on diagnostic accuracy.

RATIONALE AND OBJECTIVES: To analyze the accuracy of radiological diagnosis in MRI and CT studies of salivary gland tumors depending on the radiologist's experience. MATERIALS AND METHODS: Three radiologists with differing experience (R1 > 20, R2 > 11, and R3 > 7 years, respectively) retrospectively reviewed 128 cases (116 MRI, 12 CT studies) with suspected salivary gland tumors regarding dignity and classification using histopathology as a reference standard. Sensitivity, specificity, positive/negative predictive value and inter-observer agreement (using Cohen's κ) were calculated to compare diagnostic performance. RESULTS: Lesions were benign in 87 and in 23 cases malignant. Neoplasia was absent in 18 cases (15 cases without neoplasia and 3 cases without disease). The highest inter-observer agreement for determining dignity using CT was found between R1 and R2 (κ = 0.74, p < 0.001), and the lowest between R2 and R3 (κ = 0.28, p < 0.001). MRI sensitivity/specificity for classifying pleomorphic adenomas was as follows: R1 (100%/100%), R2 (76.92%/87.01%), R3 (43.53%/67.53%), and for CT: R1 (100%/100%), R2 (100%/88.89%), R3 (66.67%/88.89%; for Warthin's tumor using MRI: R1 (100%/97.44%), R2 (68.42%/83.33%), R3 (50.00%/67.95%), and using CT: R1 (100%/100%), R2 (50.00%/100%), R3 (100%/100%; for squamous cell carcinomas using MRI: R1 (100%/100%), R2 (75.00%/97.12%), R3 (75.00%/99.04%), and using CT: R1 (100%/100%), R2 (66.67%/88.89%), R3 (66.67%/66.67%). The highest agreement was found between R1 and R2 for MRI (κ = 0.62, p < 0.001), and the lowest between R1 and R3 at MRI (κ = 0.28, p < 0.001). CONCLUSION: Diagnostic accuracy in the assessment of salivary gland tumors strongly depends on the observer's expertise and increases with higher experience.

Correlation of lumbar lateral recess stenosis in magnetic resonance imaging and clinical symptoms.

AIM: To assess the correlation of lateral recess stenosis (LRS) of lumbar segments L4/5 and L5/S1 and the Oswestry Disability Index (ODI). METHODS: Nine hundred and twenty-seven patients with history of low back pain were included in this uncontrolled study. On magnetic resonance images (MRI) the lateral recesses (LR) at lumbar levels L4/5 and L5/S1 were evaluated and each nerve root was classified into a 4-point grading scale (Grade 0-3) as normal, not deviated, deviated or compressed. Patient symptoms and disability were assessed using ODI. The Spearman's rank correlation coefficient was used for statistical analysis (P < 0.05). RESULTS: Approximately half of the LR revealed stenosis (grade 1-3; 52% at level L4/5 and 42% at level L5/S1) with 2.2% and 1.9% respectively reveal a nerve root compression. The ODI score ranged from 0%-91.11% with an arithmetic mean of 34.06% ± 16.89%. We observed a very weak statistically significant positive correlation between ODI and LRS at lumbar levels L4/5 and L5/S1, each bilaterally (L4/5 left: rho < 0.105, P < 0.01; L4/5 right: rho < 0.111, P < 0.01; L5/S1 left: rho 0.128, P < 0.01; L5/S1 right: rho < 0.157, P < 0.001). CONCLUSION: Although MRI is the standard imaging tool for diagnosing lumbar spinal stenosis, this study showed only a weak correlation of LRS on MRI and clinical findings. This can be attributed to a number of reasons outlined in this study, underlining that imaging findings alone are not sufficient to establish a reliable diagnosis for patients with LRS.

Association between intervertebral disc degeneration and the Oswestry Disability Index.

BACKGROUND: Low back pain and lumbar intervertebral disc degeneration (IDD) are common findings. Valid data on correlation between clinical pain scores and grades of IDD are not available. OBJECTIVE: To investigate the correlation of intervertebral disc degeneration (IDD) at lumbar levels L4/5 and L5/S1 and the Oswestry Disability Index (ODI). METHODS: The lumbar discs L4/5 and L5/S1 of 591 patients were evaluated according to the 5-point (Grade I to Grade V) grading system as published by Pfirrmann et al. Functional status was assessed using the Oswestry Disability Index. Spearman's coefficient of rank correlation was used for statistical analysis (p < 0.05). RESULTS: The majority of patients revealed lumbar discs with Pfirrmann grade II to grade IV changes (93.3% at level L4/5; 89.8% at level L5/S1), while a relatively low percentage of lumbar discs presented with grade I (level L4/5: 1.5%; level L5/S1: 2.0%) or grade V (level L4/5: 5.1%; level L5/S1: 8.1%) changes, respectively. Patients' ODI scores ranged between 0 and 91.11% (arithmetic mean of 32.77% ± 17.02%). The largest group of patients (48.39%) had moderate functional disability (ODI score between 21 and 40%). There was a weak, but statistically significant positive correlation between IDD and ODI for both evaluated lumbar levels. CONCLUSIONS: Increased lumbar IDD in MRI goes along with an increased ODI. Thus, MRI is a strong indicator of a patient's clinical appearance. However, low back pain cannot be explained by imaging alone. Clinical correlation is imperative for an adequate diagnostic advance in patients with low back pain.

Does therapist's attitude affect clinical outcome of lumbar facet joint injections?

AIM: To investigate if the clinical outcome of intra-articular lumbar facet joint injections is affected by the therapist's attitude. METHODS: A total of 40 patients with facet joint-associated chronic low back pain were randomly divided into two groups. All patients received computed tomography-guided, monosegmental intra-articular facet joint injections. Following the therapeutic procedure, the patients of the experimental group (EG) held a conversation with the radiologist in a comfortable atmosphere. During the dialog, the patients were encouraged to ask questions and were shown four images. The patients of the control group (CG) left the clinic without any further contact with the radiologist. Outcome was assessed using a pain-based Verbal Numeric Scale at baseline, at 1 wk and at 1, 3, and 6 mo after first treatment. RESULTS: The patient demographics showed no differences between the groups. The patients of the EG received 57 interventional procedures in total, while the patients of the CG received 70 interventional procedures. In both groups, the pain scores decreased significantly over the entire observation period. Compared to the CG, the EG showed a statistically significant reduction of pain at 1 wk and 1 mo post-treatment, while at 3 and 6 mo after treatment, there were no significant differences between both groups. CONCLUSION: Our results show a significant effect on pain relief during the early post-interventional period in the EG as compared to the CG. The basic principle behind the higher efficacy might be the phenomenon of hetero-suggestion.

Magnetic resonance imaging-based interpretation of degenerative changes in the lower lumbar segments and therapeutic consequences.

Intervertebral disc degeneration and facet joint osteoarthritis of the lumbar spine are, among others, well known as a cause of low back and lower extremity pain. Together with their secondary disorders they set a big burden on health care systems and economics worldwide. Despite modern imaging modalities, such as magnetic resonance imaging, for a large proportion of patients with low back pain (LBP) it remains difficult to provide a specific diagnosis. The fact that nearly all the lumbar structures are possible sources of LBP, may serve as a possible explanation. Furthermore, our clinical experience confirms, that imaging alone is not a sufficient approach explaining LBP. Here, the Oswestry Disability Index, as the most commonly used measure to quantify disability for LBP, may serve as an easy-to-apply questionnaire to evaluate the patient's ability to cope with everyday life. For therapeutic purposes, among the different options, the lumbar facet joint intra-articular injection of corticosteroids in combination with an anaesthetic solution is one of the most frequently performed interventional procedures. Although widely used the clinical benefit of intra-articular steroid injections remains controversial. Therefore, prior to therapy, standardized diagnostic algorithms for an accurate assessment, classification and correlation of degenerative changes of the lumbar spine are needed.

Association between facet joint osteoarthritis and the Oswestry Disability Index.

AIM: To investigate the correlation of facet joint osteoarthritis (FJOA) at lumbar levels L4/L5 and L5/S1 and the Oswestry Disability Index (ODI). METHODS: The study involved lumbar MRIs of 591 patients with a mean age of 47.3 years. The MRIs of the lumbar spine were performed on a 1.5 Tesla scanner (Magnetom(®) Avanto, Siemens AG, Erlangen, Germany) using a dedicated receive only spine coil. After initial blinding, each dataset was evaluated by 2 board certified radiologist with more than 5 years experience in musculoskeletal imaging. In total 2364 facet joints were graded. Degenerative changes of the facet joints were evaluated according to the 4-point scale as proposed by Weishaupt et al Functional status was assessed using the ODI. The index is scored from 0 to 100 and interpreted as follows: 0%-20%, minimal disability; 20%-40%, moderate disability; 40%-60%, severe disability; 60%-80%, crippled; 80%-100%, patients are bedbound. Spearman's coefficient of rank correlation was used for statistical analysis, with significance set at P < 0.05. RESULTS: In total 2364 facet joints at lumbar levels L4/5 and L5/S1 were analysed in 591 individuals. FJOA was present in 97% (L4/L5) and 98% (L5/S1). At level L4/5 (left/right) 17/15 (2.9%/2.5%) were described as grade 0, 146/147 (24.7%/24.9%) as grade 1, 290/302 (49.1%/51.1%) as grade 2 and 138/127 (23.4%/21.5%) as grade 3. At level L5/S1 (left/right) 10/11 (1.7%/1.9%) were described as grade 0, 136/136 (23.0%/23.0%) as grade 1, 318/325 (53.8%/55.0%) as grade 2 and 127/119 (21.5%/20.1%) as grade 3. Regarding the ODI scores, patients' disability had a minimum of 0% and a maximum of 91.11% with an arithmetic mean of 32.77% ± 17.02%. The majority of patients (48.39%) had moderate functional disability (21%-40%). There was no significant correlation between FJOA and ODI on both sides of lumbar level L4/5 and on the left side of lumbar level L5/S1. A weak positive correlation was evaluated between ODI and FJOA on the right side of lumbar level L5/S1. CONCLUSION: The missing correlation of FJOA and ODI confirms our clinical experience that imaging alone is an insufficient approach explaining low back pain. Clinical correlation is imperative for an adequate diagnostic advance in patients with low back pain.

Mesenteric myolipoma.

The authors report on a case of benign myolipoma (synonym lipoleiomyoma) which was first described in 1991. The benign soft tissue tumor is composed of smooth muscle and adipose tissue and occurs sporadically in different locations. In the available literature cases were described retroperitoneal, spinal, orbital and subcutaneous and mostly have been discovered in females. Characteristically myolipomas are very large at diagnosis and reach diameters of 7 to 30 cm particularly in peritoneal or retroperitoneal localization. The sometimes enormous size leads to a displacing growth pattern which ultimately leads to the clinical symptoms. The patients often complain of nonspecific, mostly painless abdominal or thoracic pressure. Bordered by an intact capsule the tumors show no signs of malignancy and in the available literature there is no evidence of metastatic seeding. To the best of our knowledge the presented case is the first description of a diffuse mesenteric myolipoma in a male individual. In this article, we present the multidetector computed tomographic image characteristics, macroscopic appearance and histopathological findings.

Enteroclysis: Current clinical value.

AIM: To retrospectively analyze changes in clinical indication, referring medical specialty and detected pathology for small bowel double-contrast examinations. METHODS: Two hundred and forty-one (n = 143 females; n = 98 males; 01.01.1990-31.12.1990) and 384 (n = 225 females; n = 159 males; 01.01.2004-31.12.2010) patients underwent enteroclysis, respectively. All examinations were performed in standardized double-contrast technique. After placement of a nasojejunal probe distal to the ligament of Treitz, radiopaque contrast media followed by X-ray negative distending contrast media were administered. Following this standardized projections in all four abdominal quadrants were acquired. Depending on the detected pathology further documentation was carried out by focused imaging. Examination protocols were reviewed and compared concerning requesting unit, indication and final report. RESULTS: Two hundred and forty-one examinations in 1990 faced an average of 55 examinations per year from 2004-2010. There was an increase of examinations for gastroenterological (33.6% to 64.6%) and pediatric (0.4% to 7.8%) indications while internal (29.0% to 6.0% for inpatients and from 16.6% to 9.1% for outpatients) and surgical (12.4% to 7.3%) referrals significantly decreased. "Follow-up of Crohn's disease" (33.1%) and "bleeding/tumor search" (15.1%) represented the most frequent clinical indications. A total of 34% (1990) and 53.4% (2004-2010) examinations yielded pathologic findings. In the period 01.01.2004 -31.12.2010 the largest proportion of pathological findings was found in patients with diagnosed Crohn's disease (73.5%), followed by patients with abdominal pain (67.6% with history of surgery and 52.6% without history of surgery), chronic diarrhea (41.7%), suspected Crohn's disease (39.5%) and search for gastrointestinal bleeding source/tumor (19.1%). The most common pathologies diagnosed by enteroclysis were "changes in Crohn's disease" (25.0%) and "adhesions /strictures" (12.2%). CONCLUSION: "Crohn's disease" represents the main indication for enteroclysis. The relative increase of pathologic findings reflects today's well directed use of enteroclysis.

Anti-caspase-3 preconditioning increases proinsulin secretion and deteriorates posttransplant function of isolated human islets.

Human islet isolation is associated with adverse conditions inducing apoptosis and necrosis. The aim of the present study was to assess whether antiapoptotic preconditioning can improve in vitro and posttransplant function of isolated human islets. A dose-finding study demonstrated that 200 µmol/L of the caspase-3 inhibitor Ac-DEVD-CMK was most efficient to reduce the expression of activated caspase-3 in isolated human islets exposed to severe heat shock. Ac-DEVD-CMK-pretreated or sham-treated islets were transplanted into immunocompetent or immunodeficient diabetic mice and subjected to static glucose incubation to measure insulin and proinsulin secretion. Antiapoptotic pretreatment significantly deteriorated graft function resulting in elevated nonfasting serum glucose when compared to sham-treated islets transplanted into diabetic nude mice (p < 0.01) and into immunocompetent mice (p < 0.05). Ac-DEVD-CMK pretreatment did not significantly change basal and glucose-stimulated insulin release compared to sham-treated human islets but increased the proinsulin release at high glucose concentrations (20 mM) thus reducing the insulin-to-proinsulin ratio in preconditioned islets (p < 0.05). This study demonstrates that the caspase-3 inhibitor Ac-DEVD-CMK interferes with proinsulin conversion in preconditioned islets reducing their potency to cure diabetic mice. The mechanism behind this phenomenon is unclear so far but may be related to the ketone CMK linked to the Ac-DEVD molecule. Further studies are required to identify biocompatible caspase inhibitors suitable for islet preconditioning.

Facilitating cartilage volume measurement using MRI.

PURPOSE: To compare quantitative cartilage volume measurement (CVM) using different slice thicknesses. MATERIALS AND METHODS: Ten knees were scanned with a 1.5T MRI (Sonata, Siemens, Erlangen, Germany) using a 3D gradient echo sequence (FLASH, fast low-angle shot). Cartilage volume of the medial and lateral tibial plateau was measured by two independent readers in 1.5mm, 3.0mm and 5.0mm slices using the Argus software application. Accuracy and time effectiveness served as control parameters. RESULTS: Determining cartilage volume, time for calculation diminished for the lateral tibial plateau from 384.6+/-127.7s and 379.1+/-117.6s to 214.9+/-109.9s and 213.9+/-102.2s to 122.1+/-60.1s and 126.8+/-56.2s and for the medial tibial plateau from 465.0+/-147.7s and 461.8+/-142.7s to 214.0+/-67.9s and 208.9+/-66.2s to 132.6+/-41.5s and 130.6+/-42.0s measuring 1.5mm, 3mm and 5mm slices, respectively. No statistically significant difference between cartilage volume measurements was observed (p>0.05) while very good inter-reader correlation was evaluated. CONCLUSION: CVM using 1.5mm slices provides no higher accuracy than cartilage volume measurement in 5mm slices while an overall time saving up to 70% is possible.

Navigation-based needle puncture of a cadaver using a hybrid tracking navigational system.

PURPOSE: The purpose of this study was to determine the puncture accuracy of a navigational system, Medarpa, in a soft tissue environment using augmented overlay imaging. MATERIALS AND METHODS: Medarpa is an optical electromagnetic tracking system, which allows tracking of instruments, the radiologist's head position, and the transparent display. The display superimposes a computed tomography scan of a cadaver chest on a human cadaver in real time. In group A, needle puncture was performed using the Medarpa system. Three targets located inside the cadaver chest were selected. In group B, the same targets were used to perform standard computed tomography-guided puncture using a single-slice technique. A total of 42 punctures were performed in each group. Postpuncture computed tomography scans were made to verify needle tip positions. RESULTS: Mean deviation from targets was 8.42 mm +/- 1.78 mm for group A and 8.90 mm +/- 1.71 mm for group B. No significant difference was found between group A and B in any target (P > 0.05). No significant difference was found between the targets of the same group (P > 0.05). Procedural time for 42 punctures was 160 minutes in group A versus 289 minutes in group B (P < 0.05). CONCLUSION: Needle puncture in a soft tissue environment using the navigational system Medarpa can be reliably performed and matches the accuracy achieved by a computed tomography-guided puncture technique.

Facilitating coronary artery evaluation in MDCT using a 3D automatic vessel segmentation tool.

The purpose of this study was to investigate a 3D coronary artery segmentation algorithm using 16-row MDCT data sets. Fifty patients underwent cardiac CT (Sensation 16, Siemens) and coronary angiography. Automatic and manual detection of coronary artery stenosis was performed. A 3D coronary artery segmentation algorithm (Fraunhofer Institute for Computer Graphics, Darmstadt) was used for automatic evaluation. All significant stenoses (>50%) in vessels >1.5 mm in diameter were protocoled. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of coronary angiography. Sensitivity and specificity were determined for automatic and manual detection as well as was the time for both CT-based evaluation methods. The overall sensitivity and specificity of the automatic and manual approach were 93.1 vs. 95.83% and 86.1 vs. 81.9%. The time required for automatic evaluation was significantly shorter than with the manual approach, i.e., 246.04+/-43.17 s for the automatic approach and 526.88+/-45.71 s for the manual approach (P<0.0001). In 94% of the coronary artery branches, automatic detection required less time than the manual approach. Automatic coronary vessel evaluation is feasible. It reduces the time required for cardiac CT evaluation with similar sensitivity and specificity as well as facilitates the evaluation of MDCT coronary angiography in a standardized fashion.

Liver metastases in rats: chemoembolization combined with interstitial laser ablation for treatment.

PURPOSE: To assess the effect of transcatheter arterial chemoembolization (TACE) combined with laser-induced thermotherapy (LITT) for treatment of liver metastases in an animal model. MATERIALS AND METHODS: All experiments were approved by the German government and the institutional animal research review board. After subcapsular liver implantation of colorectal cancer cells in 30 WAG rats (on day 0), the animals were randomly assigned to three interventional treatment groups. In the 10 rats in group A, TACE was performed: Fourteen days after cancer cell implantation and within 20 minutes after laparotomy and retrograde placement of a microcatheter into the gastroduodenal artery, these rats were injected with mitomycin (0.1 mg), iodized oil (0.1 mL), and degradable starch microspheres (5.0 mg). In the 10 rats in group B, LITT was performed: Also on day 14, the tumors in these animals were exposed to Nd:YAG laser light of 1064 nm at 2 W for 5 minutes. In the 10 rats in group C, combined treatment was administered: TACE was performed on day 14, and LITT was performed on day 21. Tumor volumes were measured before (on day 13) and after (on day 28) treatment with magnetic resonance (MR) imaging, and the mean tumor growth ratio (day 13 tumor volume divided by day 28 tumor volume) was calculated. RESULTS: The mean tumor volumes measured before and after the treatments were, respectively, 0.11 and 0.60 cm(3) in group A, 0.11 and 0.68 cm(3) in group B, and 0.11 and 0.35 cm(3) in group C. The mean tumor growth ratio was 5.42 in group A, 6.14 in group B, and 3.15 in group C. According to Bonferroni test results, compared with the rats in groups A and B (controls), the group C rats had significantly inhibited tumor growth (P < .01 for both comparisons). CONCLUSION: Use of combined TACE-LITT treatment, compared with the use of TACE or LITT alone, significantly inhibits tumor growth.

Multislice CT of the pelvis: dose reduction with regard to image quality using 16-row CT.

To optimize examination protocols of 16-row multi-detector CT (MDCT) of pelvis for dose reduction with regard to image quality. MDCT of pelvis was performed on 12 cadaver specimens with stepwise reduction of tube current from 160 mA (113, 80, 56, 40, 28) to 20 mA at 120 kV. Scan parameters were 16 x 1.5 mm collimation. Reconstructions of axial and coronal images were used for evaluation of cortex, trabeculum, image quality, image noise, acetabulum and iliosacral (ISJ) joints. After data were blinded, evaluation of images was done by three radiologists according to 5-point Likert scale. Accuracy of the observers in sorting films according to dose reduction was determined with kappa coefficient. Mean values of image evaluation were determined. Pronounced deterioration of image quality for all criteria was observed between 80 and 28 mA. Adequate image quality was obtained at 40 mA [effective dose (E): 2.2 mSv, CTDI(w): 2.8 mGy] for criterion detailed definition of acetabulum and ISJ and at 80 mA (E: 4.4 mSv, CTDI(w): 5.6 mGy) for remaining criteria. Moderate agreement was observed between the three observers (kappa coefficient: 0.31). All observers were excellent in arranging images according to decreasing dose. Using 16-row MDCT image quality of pelvis is acceptable at 80 mA and 120 kV. This translates into a dose reduction of 33% of average value of the nationwide survey of the German Roentgen Society (1999) for this type of examination.

Quantitative cartilage volume measurement using MRI: comparison of different evaluation techniques.

This study was aimed to investigate the accuracy and time saving of MRI Argus application in the assessment of cartilage volume in osteoarthritic knees. Twelve knees of patients suffering from osteoarthritis were scanned with a 1.5 T MRI using a 3D gradient echo sequence with selective water excitation. Cartilage volume of the tibial and patellar compartment was determined with a validated multiprocessing computer system (Octane Duo, Silicon Graphics, Mountain View, Calif., USA). The calculated cartilage volumes were compared to the results acquired by the Argus (Siemens Inc., Erlangen, Germany) application software using the MRI data sets. Compared to the multiprocessing computer system a time saving of at least 30 min for cartilage volume determination was achieved. The mean differences of Argus versus the multiprocessing computer system were 4.26+/-0.84 and 7.80+/-0.87% for the medial and lateral tibial plateau and 5.94+/-0.59% for the patella (no statistical significant difference; P>0.05). The applied Argus software can be used for fast and accurate determination of cartilage volume in the knee joint.

Accuracy of biopsy needle navigation using the Medarpa system--computed tomography reality superimposed on the site of intervention.

The aim of this work was to determine the accuracy of a new navigational system, Medarpa, with a transparent display superimposing computed tomography (CT) reality on the site of intervention. Medarpa uses an optical and an electromagnetic tracking system which allows tracking of instruments, the radiologist and the transparent display. The display superimposes a CT view of a phantom chest on a phantom chest model, in real time. In group A, needle positioning was performed using the Medarpa system. Three targets (diameter 1.5 mm) located inside the phantom were punctured. In group B, the same targets were used to perform standard CT-guided puncturing using the single-slice technique. The same needles were used in both groups (15 G, 15 cm). A total of 42 punctures were performed in each group. Post puncture, CT scans were made to verify needle tip positions. The mean deviation from the needle tip to the targets was 6.65+/-1.61 mm for group A (range 3.54-9.51 mm) and 7.05+/-1.33 mm for group B (range 4.10-9.45 mm). No significant difference was found between group A and group B for any target (p>0.05). No significant difference was found between the targets of the same group (p>0.05). The accuracy in needle puncturing using the augmented reality system, Medarpa, matches the accuracy achieved by CT-guided puncturing technique.

MDCT of the proximal anastomoses created by nitinol implants in coronary artery bypass grafting: a retrospective two-observer evaluation.

The purpose of this study was to investigate the proximal anastomosis of CABG grafts created by a nitinol aortic connector. After receiving CABG, 33 patients underwent CT examination of the heart. On the same patients, CT was performed on postoperative day 5 (4-row CT, group A) and again 1 year thereafter (16-row CT, group B). Twenty-three ACVB to RCX and 27 ACVB to RCA grafts were included. Every anastomosis was reviewed under different reformations (MIP, MPR and VRT). Interobserver correlation was determined. Five days postoperatively, 48/50 anastomoses were classified as patent. One year postoperatively, 42/50 anastomoses were classified as patent. In both groups, the aortic connector could be visualized with good quality: 1.82+/-1.10 (group A) and 1.93+/-1.22 (group B) for ACVB to RCA, similar results for ACVB to RCX grafts (MPR). Image quality at the aortic connector site did not display a significant difference for any reformation between groups (P>0.05). Within groups, MPR displayed better visualization than MIP and VRT (P<0.05). In the presence of metal implants, CT provides reliable data in evaluation of the proximal anastomosis. Sixteen-row CT does not bring a significant benefit to image quality. MPR displayed the best visualization within both groups.