Evaluation of image quality, radiation dose and diagnostic performance of dual-energy CT datasets in patients with hepatocellular carcinoma

AIM

To evaluate image quality and diagnostic accuracy of different dual-energy computed tomography (DECT) datasets for identification of hepatocellular carcinoma (HCC), assess the reliability of virtual unenhanced (VU) images in replacing standard unenhanced (SU) images, and quantify effective dose (ED) at different tube voltages.

MATERIAL AND METHODS

Thirty cirrhotic patients underwent liver contrast-enhanced DECT. Two blinded observers retrospectively evaluated conventional unenhanced and VU images, 140 kVp/80 kVp/mixed tube potential arterial datasets and conventional portal-venous/late phases in consensus. Final diagnosis was based on pathological proof or imaging criteria. Image quality, ED, sensitivity, and specificity of arterial datasets were calculated.

RESULTS

Thirty-eight HCC and 18 benign lesions were detected at 80 kVp, 33 HCC and 22 benign lesions were detected at 140 kVp, and 36 HCC and 20 benign lesions were detected at mixed tube potentials. Final diagnosis confirmed 37 HCC and 20 benign lesions. There was no significant difference in diagnostic confidence between 80 kVp, 140 kVp, and mixed tube potential arterial datasets (p>0.05). Image quality was adequate for all datasets, with increased quality at higher tube potential (80 versus 140 kVp, p=0.001; mixed versus 140 kVp, p=0.001; 80 kVp versus mixed, p=0.0024). Significant ED reduction was observed between 140 and 80 kVp datasets (p<0.001).

CONCLUSIONS

The 140 kVp dataset provided higher image quality. The 80 kVp images were more sensitive in detecting HCC. VU images are adequate in replacing SU images. The ED of the 80 kVp dataset was significantly lower.

Automated calcium burden measurement in internal carotid artery plaque with CT: a hierarchical adaptive approach

AIM

Calcium burden measurement in internal carotid artery (ICA) plaque could play an important role in assessing stroke risk and stenosis quantification in the ICA. We propose an automatic method for labelling calcified plaques in ICA in CT images.

METHODS

Our approach builds upon the mean shift paradigm via an adaptive thresholding strategy. The data consists of single CT slices from 75 patients, with variety of plaque sizes and number of calcium regions. The manual measurements were carried out by a neuroradiologist for benchmarking. The calcium burden was measured as the area of the labelled plaque. Various metrics were employed to compare manual and automated measurements including correlation coefficient (CC), dice similarity (DS), Jacard Index (JI), polyline distance metric (PDM) and precision of merit (PoM).

RESULTS

We found that our automated method of calcium area characterization performed accurately compared to manual measurements with CC=0.978, and PoM=0.915. The PDM, DS, and JI, also indicate a good performance with a mean DS=0.85 (SD=0.085), a mean JI=0.747 (SD=0.12), and a mean PDM=0.195 (SD=0.177).

CONCLUSION

The proposed approach for calcium burden measurement, yields reasonably accurate labelling of calcified plaque when benchmarked against manual measurements. The approach is independent of the number and size of calcium regions, and the prototype design shows encouraging results to be adaptable to clinical practice.

Automated and accurate carotid bulb detection, its verification and validation in low quality frozen frames and motion video

AIM

Carotid intima-media thickness (cIMT) measurements during clinical trials need to have a fixed reference point (also called as bulb edge points) in the anatomy from which the cIMT can be measured. Identification of the bulb edge points in carotid ultrasound images faces the challenge to be detected automatically due to low image quality and variations in ultrasound images, motion artefacts, image acquisition protocols, position of the patient, and orientation of the linear probe with respect to bulb and ultrasound gain controls during acquisition.

METHODS

This paper presents a patented comprehensive methodology for carotid bulb localization and bulb edge detection as a reference point. The method consists of estimating the lumen-intima borders accurately using classification paradigm. Transition points are located automatically based on curvature characteristics. Further we verify and validate the locations of bulb edge points using combination of several local image processing methods such as (i) lumen-intima shapes, (ii) bulb slopes, (iii) bulb curvature, (iv) mean lumen thickness and its variations, and (v) geometric shape fitting.

RESULTS

Our database consists of 155 ultrasound bulb images taken from various ultrasound machines with varying resolutions and imaging conditions. Further we run our automated system blindly to spot out the bulbs in a mixture database of 336 images consisting of bulbs and no-bulbs. We are able to detect the bulbs in the bulb database with 100% accuracy having 92% as close as to a neurologists's bulb location. Our mean lumen-intima error is 0.0133 mm with precision against the manual tracings to be 98.92%. Our bulb detection system is fast and takes on an average 9 seconds per image for detection for the bulb edge points and 4 seconds for verification/validation of the bulb edge points.

Link between automated coronary calcium volumes from intravascular ultrasound to automated carotid IMT from B-mode ultrasound in coronary artery disease population

AIM

Establishing relationship between coronary calcium volumes from Intravascular Ultrasound (IVUS) and automated carotid intima-media thickness (cIMT) helps in understanding the genetic nature of atherosclerosis disease. In this research, we have quantified the detected calcium from IVUS video frames and associated a relationship between coronary calcium volumes computed and automated cIMT from B-mode ultrasound.

METHODS

Coronary calcium volume is computed from IVUS and auto cIMTs are computed using B-mode ultrasound. An automated computer based application is developed and tested on 100 patient volumes (an average of 2549 frames per volume) to calculate lesion area and normalized coronary calcium volume. We use an integrated approach for volume computation which is based on lesion area per frame. We have measured the normalized volume from the calcium detected video frames using proposed integration method. The cIMT of 100 carotids were measured with novel and dedicated automated software analysis (AtheroEdge™ from AtheroPoint™ LLC, Roseville, CA, USA).

RESULTS

The computer-based coronary calcium volume (from IVUS) showed a correlation coefficient with respect to cIMT for left and right carotids as 9.1% and 13.9%, respectively.

CONCLUSION

Coronary calcium volume computed from IVUS and auto cIMT are moderately correlated. The association between auto cIMT (right side) vs. computer-based coronary calcium volume (IVUS) is stronger than the association between auto cIMT (left side) vs. computer-based coronary calcium volume.

Evolutionary algorithm-based classifier parameter tuning for automatic ovarian cancer tissue characterization and classification

PURPOSE

Ovarian cancer is one of the most common gynecological cancers in women. It is difficult to accurately and objectively diagnose benign and malignant ovarian tumors using ultrasound and other tests. Hence, there is an imperative need to develop a computer-aided diagnostic (CAD) system for ovarian tumor classification in order to reduce patient anxiety and the cost of unnecessary biopsies. In this paper, we present an automatic CAD system for the detection of benign and malignant ovarian tumors using advanced image processing and data mining techniques.

MATERIALS AND METHODS

In the proposed system, Hu's invariant moments, Gabor transform parameters and entropies are first extracted from the acquired ultrasound images. Significant features are then used to train a probabilistic neural network (PNN) classifier for classifying the images into benign and malignant categories. The model parameter (σ) for which the PNN classifier performs the best is identified using a genetic algorithm (GA).

RESULTS

The proposed system was validated using 1300 benign images and 1300 malignant images, obtained from 10 patients with a benign disease and 10 with a malignant disease. We used 23 statistically significant (p < 0.0001) features. By evaluating the classifier using a ten-fold cross-validation technique, we were able to achieve an average classification accuracy of 99.8 %, sensitivity of 99.2 % and specificity of 99.6 % with a σ of 0.264.

CONCLUSION

The proposed system is automated and hence is more objective, can be easily deployed in any computer, is fast and accurate and can act as an adjunct tool in helping physicians make a confident call about the nature of the ovarian tumor under evaluation.

Correlation between fissured fibrous cap and contrast enhancement: preliminary results with the use of CTA and histologic validation

BACKGROUND AND PURPOSE

Previous studies demonstrated that carotid plaques analyzed by CTA can show contrast plaque enhancement. The purpose of this preliminary work was to evaluate the possible association between the fissured fibrous cap and contrast plaque enhancement.

MATERIALS AND METHODS

Forty-seven consecutive (men = 25; average age = 66.8 ± 9 years) symptomatic patients studied by use of a multidetector row CT scanner were prospectively analyzed. CTA was performed before and after contrast and radiation doses were recorded; analysis of contrast plaque enhancement was performed. Patients underwent carotid endarterectomy en bloc; histologic sections were prepared and evaluated for fissured fibrous cap and microvessel attenuation. The Mann-Whitney test was performed to evaluate the differences between the 2 groups. A multiple logistic regression analysis was performed to assess the effect of fissured fibrous cap and microvessel attenuation on contrast plaque enhancement. Receiver operating characteristic curve and area under the curve were also calculated.

RESULTS

Twelve patients had fissured fibrous cap. In 92% (11/12) of fissured fibrous cap-positive plaques, we found contrast plaque enhancement, whereas in 69% (24/35) of the plaques without fissured fibrous cap contrast plaque enhancement was found. The Mann-Whitney test showed a statistically significant difference between the contrast enhancement in plaques with fissured fibrous cap (Hounsfield units = 22.6) and without fissured fibrous cap (Hounsfield units = 12.9) (P = .011). On the regression analysis, both fissured fibrous cap and neovascularization were associated with contrast plaque enhancement (P = .0366 and P = .0001). The receiver operating characteristic curve confirmed an association between fissured fibrous cap and contrast plaque enhancement with an area under the curve of 0.749 (P = .005).

CONCLUSIONS

The presence of fissured fibrous cap is associated with contrast plaque enhancement. Histologic analysis showed that the presence of fissured fibrous cap is associated with a larger contrast plaque enhancement compared with the contrast plaque enhancement of plaques without fissured fibrous cap.

IOTA simple rules for discriminating between benign and malignant adnexal masses: prospective external validation

OBJECTIVE

To determine the diagnostic performance of International Ovarian Tumor Analysis (IOTA) 'simple' rules for discriminating between benign and malignant adnexal masses.

METHODS

A prospective study was performed between January 2011 and June 2012. Eligible patients were women diagnosed with a persistent adnexal mass who presented to the participating centers. Four trainees evaluated the adnexal mass by transvaginal ultrasound under the supervision of an expert examiner. The trainee analyzed the mass according to IOTA simple rules and provided a diagnosis of benign, malignant or inconclusive. All women included in the study underwent surgery and tumor removal in the center of recruitment. Diagnostic performance was assessed by calculating sensitivity, specificity and positive (LR+) and negative (LR-) likelihood ratios.

RESULTS

A total of 340 women were included (mean patient age, 42.1 (range, 13-79) years). Of the tumors, 55 (16.2%) were malignant and 285 (83.8%) were benign. The IOTA simple rules could be applied in 270 (79.4%) cases. In these cases, sensitivity was 87.9% (95% CI, 72.4-95.2), specificity 97.5% (95% CI, 94.6-98.8), LR+ 34.7 (95% CI, 15.6-77.3) and LR- 0.12 (95% CI, 0.05-0.31).

CONCLUSIONS

Application of the IOTA simple rules yielded acceptable results in terms of specificity in the hands of non-expert examiners. However, with non-expert examiners there was a 12% false-negative rate, which is relatively high.

7T mMR in the assessment of acute arterial mesenteric ischemia in a rat model

To validate a rat model of acute arterial mesenteric ischemia correlating MRI patterns with macro and microscopic changes in the small bowel. Thirty Sprague-Dawley rats were assigned to two experimental groups (Group I and Group II) of fifteen rats each. Group I underwent surgical procedure of superior mesenteric artery (SMA) ligation, followed by macroscopic observation. In Group II, a loop was tied loosely around the SMA without occluding the vessel. Three days after surgery, the loop was tied by external tips to completely occlude the artery. 7T microMR (7Tesla microMR) was performed before and 8 hours after SMA occlusion. At predetermined time-points the histopathological examinations were performed in both of groups. Macroscopic monitoring revealed thinning of mesenteric vessels, hypotonic reflex ileus and chromatic change of some loops. 7T microMR sequences evidenced loop dilation with gas-fluid mixed stasis, intraperitoneal free fluid and bowel wall hyperintensity. There were no significant differences in the histological analysis between the two groups. The gap of three days from surgery, adopted in the Group 2, allowed to avoid signs of peritoneal and mesenteric irritation which could bias imaging patterns. MR succeeded to identify the signs of arterial mesenteric ischemia.

Longitudinal analysis of heart and liver iron in thalassemia major patients according to chelation treatment

Iron chelators and nuclear magnetic resonance imaging (MRI) techniques for assessing iron loading in liver and heart have greatly improved survival of thalassemic patients suffering iron overload-associated cardiomyopathy. However, the correlation between liver iron concentration and myocardial siderosis is ambiguous. Using an objective metric of time delay, scientists have demonstrated a lag in the loading and unloading of cardiac iron with respect to that of the liver. In the present study, we further tested this hypothesis with different chelation treatments. We analyzed the effect of three chelating treatment approaches on liver and cardiac iron content in 24 highly compliant patients who underwent 3 or more MRIs under each chelation treatment. Of the 84 MRIs considered, 32 were performed on deferoxamine (DFO - 8 patients), 24 on deferiprone (DFP - 7 patients), and 28 on combined therapy (DFO+DFP - 9 patients). In patients treated with DFO, changes in cardiac iron significantly lagged changes in liver iron but the opposite pattern was observed in patients treated with DFP (p=0.005), while combined therapy showed a pattern in-between DFO and DFP. We conclude that the temporality of changes of cardiac and liver iron is chelator-dependent, so that chelation therapy can be tailored to balance iron elimination from the liver and the heart.

Automated carotid intima-media thickness and its link for prediction of SYNTAX score in Japanese coronary artery disease patients

AIM

The purpose of this study was to evaluate whether the automated carotid intima-media thickness (CIMT) identified by using automated software could predict the SYNTAX score for coronary artery disease (CAD) patients.

METHODS

Three-hundred-seventy consecutive patients (males 218; median age 69±11 years) who underwent carotid-ultrasound and coronary angiography were analyzed. Two experienced interventional cardiologists calculated the SYNTAX score from the carotid angiograms. After ultrasonographic examinations were performed, the plaque score (PS) was calculated and automated carotid IMT analysis was obtained by a fully automated algorithm. Correlation and stepwise logistic regression analysis were calculated and also the receiver operating characteristics (ROC) curve analysis was computed.

RESULTS

The mean SYNTAX score was 8.1±14.4; the PS was 7.1±14.4 and the mean CIMT was 0.86±0.23 mm (Normality rejected with a P-value of 0.001). A statistically significant correlation was found between the CIMT and SYNTAX score (r=0.323; P=0.0001) and between the PS and SYNTAX score (r=0.583; P=0.0001). The area under the ROC curve (Az) between CIMT and coronary artery disease was 0.648 (P=0.0001) and the CIMT of 1 mm or more was associated with the presence coronary artery disease with a specificity of 90.5%. Logistic regression analysis confirmed the association between CIMT and SYNTAX score (P=0.0002).

CONCLUSIONS

Results of our study using an automated algorithm showed a statistical significant association between CIMT and SYNTAX score and indicated that CIMT may be considered a reliable parameter for prediction of SYNTAX score in coronary artery disease patient population from Japan.

Carotid artery plaque characterization using CT multienergy imaging

BACKGROUND AND PURPOSE

Carotid artery plaque types can be categorized with CT according to their HU values. The purpose of this work was to analyze carotid artery plaque characteristics by using multienergy imaging.

METHODS AND MATERIALS

Thirty-two consecutive patients (23 men; median age, 70 years) were retrospectively analyzed. Carotid arteries were studied with a multienergy CT scanner. All patients received a 15-mL timing bolus of contrast medium to synchronize the data acquisition followed by an injection of 60 mL of contrast medium at a 5-mL/s flow rate. Plaque analysis in 64 carotid arteries was performed, and datasets were reconstructed by using a dedicated workstation. For each plaque, the HU value was quantified with a 2-mm-square region of interest at monoenergy values of 66, 70, 77, and 86 keV. The Wilcoxon test was used to test the differences in HU values in the plaques at different kiloelectron volts.

RESULTS

Four carotid arteries were excluded due to the absence of plaque, and another 7, because of the presence of calcified plaques. In the remaining 53 carotid arteries, Wilcoxon analysis showed a statistically significant difference in HU values among the monoenergy values of 66, 70, 77, and 86 keV (P=.0001). In particular, we found that with the increase in monochromatic kiloelectron volt values, there is a statistically significant reduction in the HU value of the plaque.

CONCLUSIONS

Results of this study suggest that the HU values of plaque may significantly change according to the selected kiloelectron volt; therefore, the HU-based plaque type (fatty, mixed, calcified) should be classified according to the energy level applied.

Tissue characterization using mean gray value analysis in deep infiltrating endometriosis

OBJECTIVES

To investigate differences in tissue characterization using three-dimensional sonographic mean gray value (MGV) between retrocervical and rectosigmoid deeply infiltrating endometriosis, and to assess intra- and interobserver concordance in MGV quantification.

METHODS

In this retrospective study, stored ultrasound volumes from 50 premenopausal women (mean age, 32 years) with 57 histologically confirmed nodules of deep endometriosis were retrieved from our database for analysis. A single experienced operator had acquired all volumes. For each nodule, the MGV was evaluated using virtual organ computer-aided analysis (VOCAL) software with semiautomated sphere-sampling (1 cm3) from the central part of the nodule. In these patients the MGV was also quantified from the myometrium of the fundal part of the uterus. In addition, two observers calculated the MGV in a subset of 24 volumes in order to quantify inter- and intraobserver agreement using intraclass correlation coefficients (ICC).

RESULTS

Mean MGV was significantly higher in rectosigmoid nodules (n = 34) than in nodules with a retrocervical location (n = 23) (23.863 vs. 17.705; P < 0.001). MGV of the myometrium was significantly higher in comparison with that of nodules in both locations (P < 0.001 for both). Intra- and interobserver measurement reproducibility was excellent (ICC > 0.95).

CONCLUSIONS

Retrocervical and rectosigmoid endometriotic nodules display significantly different MGVs. Measurement of MGV is highly reproducible and its clinical value in the diagnosis and assessment of distribution of deep endometriosis should be assessed in future studies.

Role of imaging in the management of endometriosis

The imaging techniques have a fundamental role in the diagnosis of endometriosis. Ovarian endometriosis (endometrioma) and deep endometriosis can be recognized using transvaginal ultrasound and/or magnetic resonance imaging (MRI). Although transvaginal ultrasound is the first choice of imaging modality when investigating women with pelvic pain, MRI have a role for the wider field of visions. The reproducibility of both techniques has been investigated. The three-dimensional ultrasonography has been proposed. Also studies regarding unusual localizations are reported in the literature. New insights are present about the role of imaging in the detection of the malignant transformations. This review summarizes the current evidence on the diagnostic accuracy of these two techniques in the pre-surgical assessment of endometriosis.

Computed tomography carotid wall plaque characterization using a combination of discrete wavelet transform and texture features: A pilot study

In 30% of stroke victims, the cause of stroke has been found to be the stenosis caused by plaques in the carotid artery. Early detection of plaque and subsequent classification of the same into symptomatic and asymptomatic can help the clinicians to choose only those patients who are at a higher risk of stroke for risky surgeries and stenosis treatments. Therefore, in this work, we have proposed a non-invasive computer-aided diagnostic technique to classify the detected plaque into the two classes. Computed tomography (CT) images of the carotid artery images were used to extract Local Binary Pattern (LBP) features and wavelet energy features. Significant features were then used to train and test several supervised learning algorithm based classifiers. The Support Vector Machine (SVM) classifier with various kernel configurations was evaluated using LBP and wavelet features. The SVM classifier presented the highest accuracy of 88%, sensitivity of 90.2%, and specificity of 86.5% for radial basis function (RBF) kernel function. The CT images of the carotid artery provide unique 3D images of the artery and plaque that could be used for calculating percentage of stenosis. Our proposed technique enables automatic classification of plaque into asymptomatic and symptomatic with high accuracy, and hence, it can be used for deciding the course of treatment. We have also proposed a single-valued integrated index (Atheromatic Index) using the significant features which can provide a more objective and faster prediction of the class.

Parotid gland atrophy in patients with chronic trigeminal nerve denervation

BACKGROUND AND PURPOSE

Trigeminal nerve injury or dysfunction is associated with denervation atrophy of muscles innervated by the mandibular branch of the trigeminal nerve. The purpose of our study was to evaluate the association between chronic CN V denervation and parotid gland atrophy.

MATERIALS AND METHODS

Twenty-six patients with chronic masticator muscle atrophy were retrospectively identified and evaluated for the presence of ipsilateral parotid gland atrophy. Twenty-six age-matched control subjects with no clinical or imaging evidence of chronic masticator space atrophy were also identified. Segmentation of the parotid gland was performed to calculate a parotid asymmetry index. The Fisher exact test and t test were respectively used to determine the correlation between parotid gland atrophy and ipsilateral masticator muscle atrophy and to evaluate any difference in the size of the involved parotid gland when compared with that in the control subjects.

RESULTS

Ipsilateral parotid gland atrophy was seen in 9/26 (42.8%) patients with fatty replacement of the masticator group of muscles, suggesting a correlation between parotid gland atrophy and CN V denervation (P<.001). The parotid asymmetry index was significantly different in patients with CN V denervation (0.59±0.25) compared with control subjects (0.92±0.03) (P<.001).

CONCLUSIONS

Ipsilateral parotid gland atrophy can accompany chronic CN V denervation change, and its clinical significance remains to be determined.

What is the correct distance measurement metric when measuring carotid ultrasound intima-media thickness automatically?

AIM

The aims of this study were: 1) to analyze the interobserver carotid intima-media thickness (CIMT) variability using three different measurement metrics on large multi-institutional databases; 2) to evaluate the three kinds of metrics when comparing completely automated CIMT measurement (Auto Edge CIMT) to two manually derived CIMT (manual CIMT).

METHODS

Two expert sonographers manually analyzed 665 carotid B-Mode ultrasound images collected from five institutions and using four different scanners. The two readers traced the lumen-intima (LI) and media-adventitia (MA) interfaces. The manual CIMT was computed from the LI/MA tracings by using three different distance measurement metrics: the Hausdorff, the PolyLine, and the Centerline distance metrics. The LI/MA tracings of a completely automated method we previously developed were then compared to manual CIMT.

RESULTS

The average CIMT values of Readers 1 and 2 were 1.904±0.650 mm and 1.421±0.394 using Hausdorff, 0.808±0.269 mm and 0.790±0.227 mm using Polyline, and 0.762±0.266 mm and 0.782±0.228 mm using Centerline, respectively. The correlation coefficients were 0.14 (0.07-0.22) for Hausdorff, 0.77 (0.74-0.80) for Polyline, and 0.82 (0.79-0.84) for Centerline. The variation coefficients (CV) were equal to 46.4% (Hausdorff), 2.6 % (Polyline), and 14.1% (Centerline). The Auto Edge CIMT values were: 1.655±0.676 mm using Hausdorff, 0.808±0.282 mm using Polyline, and 0.776±0.275 mm using Centerline.

CONCLUSION

Centerline and Polyline yield very close results and are clinically suitable distance measurement techniques for computing the CIMT from LI/MA profiles.

Association between carotid artery plaque type and cerebral microbleeds

BACKGROUND AND PURPOSE

CMBs have become increasingly recognized with the widespread use of MR imaging techniques that are sensitive to iron deposits. The purpose of this study was to correlate the presence of CMBs and carotid plaque characteristics.

MATERIAL AND METHODS

Seventy consecutive patients (47 men; 23 women; mean age, 65 years) were prospectively analyzed. Carotid arteries were studied using a 16-detector row CT scanner, whereas the brain was explored with an MR imaging 1.5T system. CMBs were studied using a T2*-weighted GRE sequence. CMBs were classified by an ordinal scale and carotid plaques were characterized based on their composition as fatty, mixed, or calcified. Patients were classified as symptomatic and asymptomatic. Chi-square and multiple logistic regression analyses, as well as ROCs, were calculated.

RESULTS

The prevalence of CMBs was 30%. A statistically significant difference in CMB prevalence was observed between symptomatic (46%) and asymptomatic (19%) patients (P value = .0021; OR = 3.7). Correlation analysis demonstrated an association between the number of CMBs and the symptoms (P = .0001). A statistically significant association was observed between the presence of fatty plaque and CMBs (P = .0019).

CONCLUSIONS

The results of this study suggest an association between the presence of carotid artery fatty plaque, symptoms, and CMBs. Moreover, we found that the presence (and entity) of CMBs may represent an indicator of cerebrovascular symptom severity.

Carotid artery plaque classification: does contrast enhancement play a significant role?

BACKGROUND AND PURPOSE

Previous articles have demonstrated that carotid artery plaques may have enhancement after administration of contrast material. The purpose of this study was to evaluate the effect of enhancement in carotid artery classification.

MATERIALS AND METHODS

Three hundred eighty consecutive patients (235 men, 145 women; median age 64, age range 32-87 years) were analyzed using a multidetector row CT scanner. Examinations were performed before and after CM administration. Carotid artery plaques with a attenuation value <60 HU were considered fatty, those from 60-130 HU were considered mixed, and those >130 HU were considered calcified. χ(2) tests, Student t tests, and Cohen analyses were performed.

RESULTS

Before CM administration, we observed 226 calcified, 175 mixed, and 206 fatty plaques; after CM administration, 229 calcified, 213 mixed, and 165 fatty plaques were observed. A statistically significant difference between these 2 groups was observed (P = .016). We found that 19.9% of fatty plaques become mixed (n = 41), whereas 1.7% of the mixed plaques become calcified (n = 3). All calcified plaques remained in the same category. Fatty plaques that changed type showed a larger enhancement compared with those that remained in the same class (P = .001). Cohen analyses showed very good agreement between observers before (κ = 0.834) and after contrast material administration (κ = 0.86).

CONCLUSIONS

The results of this study indicate that the carotid artery plaques (fatty and mixed) significantly change according to whether analysis is performed before or after administration of contrast material.

Automated carotid IMT measurement and its validation in low contrast ultrasound database of 885 patient Indian population epidemiological study: results of AtheroEdge™ Software

AIM

The aim of this paper was to demonstrate the usage of an automated computer-based IMT measurement system called - CALEX 3.0 (a class of patented AtheroEdge™ software) on a low contrast and low resolution image database acquired during an epidemiological study from India. The image contrast was very low with pixel density of 12.7 pixels/mm. Further, to demonstrate the accuracy and reproducibility of the AtheroEdge™ software system we compared it with the manual tracings of a vascular surgeon--considered as a gold standard.

METHODS

We automatically measured the IMT value of 885 common carotid arteries in longitudinal B-Mode images. CALEX 3.0 consisted of a stage for the automatic recognition of the carotid artery and an IMT measurement modulus made of a fuzzy K-means classifier. Performance was assessed by measuring the system accuracy and reproducibility against manual tracings by experts.

RESULTS

CALEX 3.0 processed all the 885 images of the dataset (100% success). The average automated obtained IMT measurement by CALEX 3.0 was 0.407±0.083 mm compared with 0.429 ± 0.052 mm for the manual tracings, which led to an IMT bias of 0.022±0.081mm. The IMT measurement accuracy (0.022 mm) was comparable to that obtained on high-resolution images and the reproducibility (0.081 mm) was very low and suitable to clinical application. The Figure-of-Merit defined as the percent agreement between the computer-estimated IMT and manually measured IMT for CALEX 3.0 was 94.7%.

CONCLUSION

CALEX 3.0 had a 100% success in processing low contrast/low-resolution images. CALEX 3.0 is the first technique, which has led to high accuracy and reproducibility on low-resolution images acquired during an epidemiological study. We propose CALEX 3.0 as a generalized framework for IMT measurement on large datasets.

Carotid artery wall thickness measured using CT: inter- and intraobserver agreement analysis

SUMMARY

The purpose of this work was to compare inter- and intraobserver agreement in the analysis of CAWT by using MDCTA. The CAWT in 35 patients was quantified by 4 observers. Bland-Altman statistics were used to measure the agreement between observers. The results of our study demonstrated that the CAWT measured by using MDCTA shows a good reproducibility between observers by considering inter- and intraobserver agreement.

Low-dose contrast-enhanced time-resolved MR angiography at 3T: diagnostic accuracy for treatment planning and follow-up of vascular malformations

AIM

To assess the accuracy of low-dose contrast-enhanced time-resolved 3T magnetic resonance angiography (MRA) for the morphological and functional assessment of vascular malformations (VM), and to evaluate its diagnostic potential for the depiction of treatment-induced changes.

MATERIALS AND METHODS

Twenty-five patients with known VM underwent MRA to evaluate the location and extent of lesions and their haemodynamic characteristics. Three-dimensional (3D) T1-weighted time-resolved sequences were acquired following the administration of 0.05mmol/kg of gadobenate dimeglumine. VM were classified according to their morphology and haemodynamic characteristics. All patients thereafter underwent conventional angiography to confirm the diagnosis and to treat the lesions (embolization or sclerotherapy). Follow-up MRA was performed 30 days after treatment to assess morphological and functional changes. A visual analogue scale (VAS) was used to clinically assess the severity of symptoms before and after therapy.

RESULTS

Based on haemodynamic characteristics, VM were classified as predominantly arterial [4 (16%)], artero-venous [19 (76%)] or venous [2 (8%)]. Twenty-three (92%) lesions were classified as high-flow VM and two (8%) as low-flow VM. Intralesional thrombosis was present in 17 (68%) lesions before therapy and in 10 lesions (40%) after therapy. The median VAS scores were 5±1 before treatment and 4±2 after treatment. Very good correlation (Spearman's correlation coefficient: rho=0.87; p=0.000) was noted between the reduction of lesion size on follow-up MRA and pain relief as assessed by VAS.

CONCLUSION

Low-dose contrast-enhanced time-resolved 3T MRA can be used to define morphological and functional aspects of VM accurately during treatment planning and follow-up, and can identify post-therapy changes that positively correlate with treatment outcome.

Carotid plaque enhancement and symptom correlations: an evaluation by using multidetector row CT angiography

BACKGROUND AND PURPOSE

The identification of plaque characteristics that determine its vulnerability is extremely important. The purpose of this work was to evaluate CPE after administration of contrast material and to assess whether there is a statistical association between CPE and cerebrovascular symptoms.

MATERIALS AND METHODS

Ninety-seven consecutive patients (69 men, 28 women; mean age, 62 years; age range, 39-82 years), studied by using an MDCT scanner, were retrospectively analyzed. Examinations were performed before and after administration of contrast medium. Plaque enhancement was analyzed, and the obtained data were compared with the patient's symptoms. Patients were classified as symptomatic (TIA or stroke with a temporal window of 6 months) or asymptomatic according to neurologic assessment and the TOAST criteria. The ROC curve and Az were calculated, and multiple logistic regression analysis was performed.

RESULTS

Thirty-nine patients were excluded because they had calcified plaques (40.2%). CPE was observed in 74% of the remaining 58 patients. A statistically significant difference was observed between symptomatic and asymptomatic patients for the presence of CPE (P = .0013; OR = 7.5). Moreover, we observed that CPE was higher in fatty plaques (P = .035) than in mixed ones and more frequent in the former (P = .0119). The ROC curve demonstrated that a threshold of 15 HU is associated with a specificity and sensitivity of 83.33% and 76.47%, respectively. Multiple logistic regression showed that CPE and symptoms are associated (P = .0315).

CONCLUSIONS

The results of our study suggest that for noncalcified carotid plaques, the presence of CPE is associated with cerebrovascular symptoms. Fatty plaques are more likely to have CPE compared with mixed plaques.

Carotid artery wall thickness and leukoaraiosis: preliminary results using multidetector row CT angiography

BACKGROUND AND PURPOSE

LA is a condition caused by chronic cerebral ischemia and it represents an independent risk for stroke. The purpose of this work was to determine whether CAWT studied by using MDCTA is correlated with LA and its severity.

MATERIALS AND METHODS

Ninety-eight patients ≥60 years of age were retrospectively studied by using multidetector row CT. Supra-aortic vessel analysis and brain CT were performed in the same procedure. In each patient, CAWT was measured with an internal digital caliper, and the presence and severity of LA were assessed. Correlation coefficients by using Spearman statistics and ROC curves were calculated. A P value < .05 was considered statistically significant.

RESULTS

Measurements of the distal common CAWT ranged from 0.5 to 1.53 mm. A correlation between LA and increased CAWT was observed (Pearson correlation, 0.33; P < .001). On the basis of a threshold of 0.9 mm, an important statistical association between increased CAWT and LA (P < .0001) was found. With the same threshold, ROC curve analysis indicated a sensitivity of 55% and a specificity of 75% for LA.

CONCLUSIONS

The results of this study show a statistically significant correlation between increased CAWT and LA (and its severity).

Pros and cons of dexamethasone suppression test for screening of subclinical Cushing's syndrome in patients with adrenal incidentalomas

The results of dexamethasone suppression tests (DST) in the screening of subclinical hypercortisolism are not readily comparable. Aim of the present study was to review the effectiveness of overnight 1-mg DST and 8-mg DST to look for functional autonomy of clinically inapparent adrenal adenomas. Sixty-eight consecutive patients with clinically inapparent adrenal adenomas were enrolled. All patients underwent 1-mg DST. The 8-mg DST was performed in the 11 patients who had post 1-mg DST cortisol >138 nmol/l and in 11 patients who had post 1-mg DST cortisol between 50 and 138 nmol/l. The a priori probability to have autonomous cortisol secretion was defined by the presence of at least two alterations of the hypothalamic-pituitary-adrenal axis among reduced ACTH concentrations, elevated urinary free cortisol (UFC) or elevated midnight serum cortisol. Cortisol levels >138 nmol/l after the 1-mg DST increases the post-test probability of adrenal functional autonomy to 55%, whereas cortisol levels <50 nmol/l reduce the post-test probability to 8%. Cortisol levels recorded after the 8-mg DST were nonsignificantly lower than after the 1-mg DST and all the patients with cortisol >138 nmol/l after the 1-mg DST maintained cortisol above this cut-point. The 1-mg DST should be considered as the more effective test to detect autonomous cortisol secretion by a clinically inapparent adrenal adenoma when cortisol levels are >138 nmol/l, while cortisol levels <50 nmol/l reduce remarkably the post-test probability of this event. The 8-mg DST seems to replicate by large the results of the 1-mg DST.

Role and application of hysterosalpingography and Fallopian tube recanalization

AIM

The prevalence of infertility in the United States is 15-20% and this condition represents an important medical problem. The purpose of this work was to evaluate therapeutical efficacy of 2 consecutive hysterosalpingography (HSG) followed each other after 4 week compared with the fallopian tube recanalization (FTR).

METHODS

Two groups of 80 patients paired for mean age and age range (age range, 23-37 years; mean age, 30 years), were assessed for pregnancy rate (two-year follow-up) by using two consecutive HSG in one group and HSG and tube recanalization in the second group. Pain perception and dose delivered were assessed. Statistical analysis was performed to evaluate significant differences between the two approaches.

RESULTS

Pregnancy rate after TFR was 51% whereas pregnancy rate after two consecutive HSG was 31.3% (P= 0.016; OR 2.31) and all the pregnancies were observed in those women that showed a positive variation in second HSG with a pregnancy rate of 47% (P=0.776; OR=1.18). In one case a serious complication was observed (1.25%): a tubal perforation. Minor bleeding sometimes lasted for as long as 48 h but never required any medical treatment. Pain assessment and dose delivered were statistically different by using these two methods (P= 0.027 and P<0.001, respectively)

CONCLUSION

Therapeutical efficacy of two consecutive HSG followed each other after four week compared with the FTR are similar when the second HSG shows the presence of Fallopian tube patency.

Associations between carotid artery wall thickness and cardiovascular risk factors using multidetector CT

BACKGROUND AND PURPOSE

It has been demonstrated that the increase in CAWT is associated with an increased risk of stroke and its severity. The aim of this study was to determine whether CAWT evaluated by MDCTA is associated with the following cardiovascular risk factors: hypertension, diabetes mellitus, dyslipidemia, and smoking.

MATERIALS AND METHODS

This was a retrospective study. One hundred sixty-eight patients (120 men; mean age, 68.96 years ± 11.2 years SD) were analyzed by using a multidetector row CT scanner. In each patient, CAWT was measured by using an internal digital caliper. Continuous data were described as the mean value ± SD and were compared by using the Student t test. We performed simple logistic regressions to evaluate the association between CAWT and the following: hypertension, diabetes mellitus, dyslipidemia, and smoking. A P value < .05 indicated statistical significance.

RESULTS

The distal common CAWT varied from 0.5 to 1.5 mm. We observed that hypertension and diabetes mellitus were associated with increased (>1 mm) CAWT (P = .0041 and P = .0172, respectively). There was no significant association between increased CAWT and dyslipidemia or smoking.

CONCLUSIONS

In our selected group, the results of this work show that an increased CAWT is associated with the cardiovascular risk determinants hypertension and diabetes. Further studies are necessary to evaluate whether it is possible to apply our observations to the general population.

Study of endoleaks after endovascular repair by using MDCTA

PURPOSE

Our purpose was to investigate the multi-detector-row CT angiography (MDCTA) application in endoleak detection.

METHODS

Fifty-nine patients that underwent endovascular aneurysm repair (EVAR) of an infrarenal abdominal aortic aneurysm with endoluminal stent graft were retrospectively studied. MDCTA scans were obtained after administration of 110-130 mL of contrast material using a 4-6 mL/sec flow rate. We made unenhanced, arterial (15-20 sec) and delayed (100 sec) acquisitions. For each patient four MDCTA datasets (pre-EVAR, 1, 6, and 12 months follow-up) were obtained. Each examination was studied by two observers. Kappa value was calculated in order to evaluate inter-observer agreement.

RESULTS

Twenty-one endoleaks were detected in eighteen patients. Fifteen and eighteen endoleaks were detected by using biphasic arterial CT and biphasic delayed CT respectively (sensitivity of 71.4% and 85.7% respectively). We observed a positive correlation between the presence of endoleak and the increasement in aneurysm size. Interobserver agreement was 88.1% and kappa value was 0.685.

CONCLUSIONS

Biphasic CT for endoleak detection is significantly superior to arterial and delayed phases respectively. We observed a good interobserver agreement.

Superior mesenteric artery spontaneous and isolated dissection diagnosed by using MDCTA

We report the case of a 49-year-old man admitted to our Institute because he suffered acute abdominal pain induced by eating. Sonography don't revealed pathological findings. Then underwent a multi-detector row computed tomography angiography (MDCTA) that revealed an intimal flap separating true and false lumens that was located 2 cm from the origin of the superior mesenteric artery (SMA) and with an extension of 8 cm. Since the dissection was limited without occlusion of the SMA and the mesenteric marginal artery served as a collateral vessel on the distal side of the SMA, the treatment has been conservative. Improved CT technology facilitates the diagnosis of superior mesenteric artery dissection. Prompt diagnosis and treatment result in the lowest mortality rate and minimize the prevalence of intestinal infarction. Only 107 cases (including the present case) of isolated spontaneous SMA dissection without associated aortic dissection were identified from the literature.

Assessment of intracranial arterial stenosis with multidetector row CT angiography: a postprocessing techniques comparison

BACKGROUND AND PURPOSE

It was demonstrated the some patients with stroke have intracranial stenosis of 50% or greater and the identification of intracranial arterial stenosis is extremely important in order to plan a correct therapeutical approach. The aim of this study was to assess the image quality and intertechnique agreement of various postprocessing methods in the detection of intracranial arterial stenosis.

MATERIAL AND METHODS

Eighty-five patients who were studied by using a multidetector row CT scanner were retrospectively analyzed. A total of 2040 segments were examined in the 85 subjects. Intracranial vasculature was assessed by using MPR, CPR, MIP, and VR techniques. Two radiologists reviewed the CT images independently. Cohen weighted kappa statistic was applied to calculate interobserver agreement and for image accuracy for each reconstruction method. Sensitivity, specificity, PPV, and NPV were also calculated by using the consensus read as the reference.

RESULTS

Two hundred fifteen (10.5%) stenosed artery segments were identified by the observers in consensus. The best intermethod kappa values between observers 1 and 2 were obtained by VR and MIP (kappa values of 0.878 and 0.861, respectively), whereas MPR provided the lowest value (kappa value of 0.282). VR showed a sensitivity for detecting stenosed segments of 88.8% and 91.6% for observers 1 and 2, respectively. The highest positive predictive value was also obtained by VR at 95% and 99% for observers 1 and 2, respectively. Image accuracy obtained by using VR was the highest among all reconstruction methods in both observers (185/255 and 177/255 for observers 1 and 2, respectively).

CONCLUSIONS

The results of our study suggest that VR and MIP techniques provide the best interobserver and intertechnique concordance in the analysis of intravascular cranial stenosis.

Imaging of the endoleak after endovascular aneurysm repair procedure by using multidetector computer tomography angiography

Abdominal aortic aneurysms (AAA) are an important cause of death in elderly men. Most used treatment options are endovascular aneurysm repair (EVAR) and open surgical repair. After the endovascular stent graft placement, however, several complications may occur and an important complication of EVAR is endoleak formation which occurs in approximately one-fourth of patients. Endoleak represents a blood flow outside the stent graft lumen but within the aneurysm sac. For these reasons, unlike the minimal imaging follow-up that is typically performed after surgical repair, patients undergoing EVAR require a life-long postoperative surveillance imaging. In the last years, with the advent of multidetector-row CT (MDCT) scanners and the use of specific angiographic protocols (multidetector CT angiography, MDCTA), CT imaging became the most commonly used examination for endoleak detection. Moreover, the volume data obtained can be further rendered to generate high quality two-dimensional (2D) and three-dimensional (3D) images, that allow a better distinction between Endoleak type II, III and IV. Purpose of this study was to review and describe MDCTA potentialities in the detection of endoleak after EVAR procedures.

Window settings for the study of calcified carotid plaques with multidetector CT angiography

SUMMARY

CT angiography (CTA) shows high sensitivity in detecting calcified plaques, but sometimes a bias in the exact quantification of stenosis degree occurs, mainly caused by the high linear attenuation coefficient of the calcified plaques. The purpose of this technical study was to evaluate the most appropriate CT window parameters for the assessment of calcified plaques stating which of them can provide the best inter-observer agreement. Scatter-plots and regression results showed the correlation between both width and level respectively depending on intraluminal Hounsfield units (HU) value (width = intraluminal HU x 2.07; level = intraluminal HU x 0.72). Obtained data indicated that the presence of different stenosis degrees did not modify visualization parameters.

Surgical correction and MR imaging of double lip in Ascher syndrome: record of a case and a review of the literature

A double-lip is an infrequent anomaly which may occur either isolated or as a component of Ascher's syndrome. Apart from a deformity that may interfere with speech and mastication, surgery may be indicated for cosmetic reasons. We present a case of a male patient with an acquired double lip and blepharochalasis. In order to make the differential diagnosis a magnetic resonance imaging (MRI) was performed. The mass was removed by a transverse elliptical incision under local anesthesia. No post-operative problems occurred and the cosmetic result was good.

Multidetector row CT of the brain and carotid artery: a correlative analysis

AIM

To evaluate the association between types of carotid plaque, the presence of prior ischaemic events detectable with CT, and patient's symptoms.

MATERIALS AND METHODS

Between January 2004 and May 2006, 112 patients were evaluated using multidetector row computed tomography angiography (MDCTA) of the carotid arteries and computed tomography (CT) of the brain. Carotid arteries were categorized by evaluating the degree of stenosis according to North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria, the type of plaque, and the presence of plaque ulceration. The brain was assessed via CT for the presence, type, and position of lesions. Chi-square tests, Student's t test, and simple logistic regression analysis were performed and the Cohen kappa test was applied for interobserver variability measurement.

RESULTS

The Chi-square test indicated a statistically significant association between the presence of fatty plaques (p=0.005) and CT-detectable lesions in the brain (p=0.004). Moreover, the number of patients with CT-detectable brain lesions was greater in patients with >70% stenosis than in those with <70% stenosis (p=0.007). Logistic regression confirmed the association between fatty plaque and symptoms (p=0.001), between >70% stenosis and symptoms (p=0.041), and an inverse association between calcified plaque and symptoms (p=0.009).

CONCLUSION

MDCTA allows adequate evaluation of the type of plaque. The results of the present study indicate that there is an association between cerebral lesions, symptoms, and fatty plaque in the carotid artery. The degree of stenosis also correlated with cerebral lesions and symptoms. According to the obtained data, the type of carotid plaque should be included among primary parameters in the classification of patients' risk class.

Multi-detector-row CT of muscles with volume rendering technique

The aim of this paper was to analyze the concept of volume rendering (VR) technique in order to define and visualize the muscles by using multi-detector-row computed tomography (MDCT) scanner. Second, to understand the current indications for performing MDCT study of the muscles underlining radiation exposure and diagnostic efficacy. Thanks to the use of fast scanning and thin collimation, MDCT can obtain near-isotropic voxels, providing an excellent image detail. Moreover, with the use of postprocessing procedures it is possible to obtain volumetric images with an impressive visual impact (dissection-like images). With the use of correct techniques, in particular VR reconstruction, it is currently possible to define body musculature detecting pathological alterations. The aim of this review was to describe the procedure to obtain a correct visualization of the body muscles and to show volume rendered images supplied by this postprocessing technique. The authors retrospectively studied 30 patients by using a MDCT. Each time projection data were reconstructed to generate section thickness as thinnest as possible which were then reprocessed to obtain VR images. For the whole patient cohort the authors generated multiple VR reconstructed images in order to define the most efficient strategies to evaluate the different types of muscles. MDCT can provide excellent visualization of the superficial musculature, in particular it defines with accuracy normal anatomy. A correct reconstruction of projectional data is important to achieve high quality images.

Diagnostic sensitivity of multidetector-row spiral computed tomography angiography in the evaluation of type-II endoleaks and their source: comparison between axial scans and reformatting techniques

BACKGROUND

After endovascular stent-graft placement, several complications may occur. Retrograde filling of the aneurysm (type-II endoleak) is the most common.

PURPOSE

To evaluate the accuracy, image quality, and interobserver agreement of multidetector-row spiral computed tomography angiography (MDCTA) in the diagnosis of type-II endoleak, by using various types of reformatting techniques in comparison to regular axial images.

MATERIAL AND METHODS

Twenty-four patients who had had endovascular repair of an infrarenal abdominal aortic aneurysm with stent graft were retrospectively studied. In 12 of 24 patients, a type-II endoleak was found. CT scans were obtained after intravenous administration of 130 ml of nonionic contrast material using a 4-6-ml/s flow rate. All patients were investigated with axial scans, multiplanar reconstruction (MPR), maximum intensity projection (MIP), shaded-surface display (SSD), and volume-rendering (VR) techniques. For each patient and for each reconstruction method, the image quality of the scans was scored as 0 for bad quality, 1 for poor quality, 2 for good quality, and 3 for excellent quality images. Two radiologists reviewed the CT images independently. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each reconstruction method, with the axial images as the reference method. Interobserver agreement and kappa value were also recorded.

RESULTS

MPR showed the highest sensitivity (83% and 67% for observers 1 and 2, respectively), PPV (91% and 80% for observers 1 and 2, respectively), and NPV (85% and 71% for observers 1 and 2, respectively), whereas VR showed the highest specificity (92% for both observer 1 and 2).

CONCLUSION

Reformatting techniques provide good-quality images; nevertheless, their efficacy in the study of type-II endoleak was found to be suboptimal in comparison to regular axial images. The MPR technique is probably the best choice in conjunction with axial images.

Osteoma of the mandible: case report and application of multi-detector-row CT rendering technique

Osteoma is an uncommon benign slow growing neoplasm of the bone, characterized by proliferation of osteoblasts forming bone trabeculas in a connective tissue stroma. After paranasal sinus, mandible is its second most frequent location. The osteoma can be central, peripheral or of extraskeletal type. Peripheral osteomas are quite uncommon. This fact suggests that peripheral osteoma of the mandible may be traumatically damaged, mostly because of muscle traction. This paper reports a case of peripheral osteoma located in the mandible. The patient underwent a multi-detector-row computed tomography (MDCT) in order to plan corrective surgery. MDCT images were post-processed with volume rendering techniques.

Accessory renal artery stenosis and hypertension: are these correlated? Evaluation using multidetector-row computed tomographic angiography

BACKGROUND

Renal artery stenosis may produce hypertension, and this condition is referred to as renovascular hypertension (RVH).

PURPOSE

To evaluate, by using multidetector-row spiral computed tomographic angiography (MDCTA), whether a relationship between accessory renal artery stenosis and hypertension may be hypothesized.

MATERIAL AND METHODS

214 patients (142 males, 72 females; mean age 66 years) who had previously undergone an MDCTA to study the abdominal vasculature were retrospectively studied. Patients with renal artery stenosis (RAS) were excluded from this analysis. The patients were studied by means of a four-detector-row CT, and scans were obtained after intravenous bolus administration of 110-140 ml of a nonionic contrast material with a 3-6 ml/s flow rate. As a second step, by means of statistical analysis, hypertension data were compared with findings of accessory artery stenosis. Two radiologists first independently reviewed the MDCTA images and then, in case of disagreement, in consensus. Interobserver agreement was calculated for all measurements.

RESULTS

The overall number of detected accessory renal arteries was 74 in 56 of the 214 patients. Accessory renal artery stenosis was detected in 21 of the 56 patients. There was a difference in the prevalence of hypertension between patients with (n = 21) and without (n = 35) accessory renal artery stenosis (P = 0.0187). Interobserver agreement was good (kappa value 0.733).

CONCLUSION

Any statistical association between the presence of accessory renal artery stenosis and hypertension could not be disclosed. However, accessory renal artery stenosis, detected by MDCTA, is an important pathological sign that the radiologist has to assess in the light of its possible association with hypertension.

Differences between MIP and MPR techniques in the carotid artery stenosis degree measurement. Evaluation using multi-detector-row CT angiograph

AIM

Stroke is the third leading cause of mortality in the world and the stenosis degree is considered a fundamental parameter for the definition of the therapeutic approach. With the development of Multi-Detector-Row CT (MDCTA) scanner, computed tomography has become a widely used imaging technique for categorizing carotid artery stenosis degree. The purpose of this paper is to compare two CT post-processing procedures, maximum intensity projection (MIP) and multi planar reconstruction (MPR) in order to evaluate their sensitivity and inter-technique agreement.

METHODS

For the purpose 45 patients (35 males and 10 females), that underwent MDCTA for carotid artery evaluation, have been retrospectively evaluated. Data set were processed with the study group's workstations, by using MPR and MIP algorithms. Each patient was assessed for stenosis degree by using North American Symptomatic Carotid Endarterectomy Trial method. Statistic analysis was performed to determine the sensitivity of the used procedure. The Cohen kappa test was applied to assess the level of intra-observer agreement. Image quality was also evaluated.

RESULTS

MPR sensitivity was 87.8% (95% confidence interval [CI] 81-94.5%) and MIP sensitivity was 91.1% (95% CI 85.2-97%). Agreement in MPR was 0.792 with a standard error (SE) of 0.066, and agreement in MIP was 0.836, with a SE of 0.072.

CONCLUSION

Results of the study indicate the MIP algorithm is more sensitive than MPR. Best intra-observer agreement and image quality results were also observed in the MIP. Data suggest also that MIP should be the post-processing procedure to be utilized in the evaluation of carotid artery stenosis degree, when using MDCTA. Presence of big calcified plaque can determine difficulties in MIP evaluation of stenosis degree.

CT and ultrasound in the study of ulcerated carotid plaque compared with surgical results: potentialities and advantages of multidetector row CT angiography

BACKGROUND AND PURPOSE

Ulceration is a severe complication of carotid plaque. The purpose of this study was to evaluate the role and the diagnostic efficacy of multidetector row CT angiography (MDCTA) and ultrasound (US) echo color Doppler (US-ECD) in the study of patients with carotid plaque complicated by ulceration through the comparison with the surgical observation.

MATERIALS AND METHODS

From January 2004 to October 2005, 237 patients, for a total of 474 carotid arteries, studied at first with color Doppler US, were analyzed using CT angiography. A total of 103 patients underwent a carotid endarterectomy. We analyzed stenosis degree, plaque composition, and presence of ulcerations. In a second phase, the data were compared with the surgical results when the MDCTA indicated surgical intervention.

RESULTS

MDCTA found 31 ulcerations; the surgical confirmation underlined a 93.75% sensitivity and a 98.59% specificity. US-ECD performances were 37.5% and 91.5% for sensitivity and specificity, respectively. The number of patients who showed plaque ulcerations increased with the severity of stenosis. Furthermore, ulcerations of the carotid plaque occurred more often proximal than distal to the point of maximum stenosis, and this trend increased with the severity of the stenosis. We also determined that fatty plaques were more likely to be affected by ulcerations.

CONCLUSIONS

The results of our study suggest that MDCTA detects with higher sensitivity and specificity the presence of ulcerated plaque compared with US-ECD, which has been demonstrated to be less effective in this evaluation. Considering the high MDCTA sensitivity and specificity for detection of plaque ulceration, we therefore recommend MDCTA as a useful step for correct presurgical planning.