Predictive factors of diagnostic accuracy of CT-guided transthoracic fine-needle aspiration for solid noncalcified, subsolid and mixed pulmonary nodules

Purpose

The aim of this study was to analyse factors predicting the diagnostic accuracy of computed tomography (CT)-guided transthoracic fine-needle aspiration (TTFNA) for solid noncalcified, subsolid and mixed pulmonary nodules, with particular attention to those responsible for false negative results with a view to suggesting a method for their correction.

Materials and methods

From January 2007 to March 2010, we retrospectively reviewed the CT images of 198 patients of both sexes (124 males and 74 females; mean age, 70 years; range age, 44–90) used for the guidance of TTFNA of pulmonary nodules. Aspects considered were: lesion size and density, distance from the pleura, and lesion site. Multiplanar reformatted images (MPR) were retrospectively obtained in the sagittal and axial oblique planes relative to needle orientation.

Results

The overall diagnostic accuracy of TTFNA CTguided biopsy was 86% for nodules between 0.7 and 3 cm, 83.3% for those between 0.7 and 1.5 cm, and 92% for those between 2 and 3 cm. Accuracy was 95.1% for solid pulmonary nodules, 84.6% for mixed nodules, and 66.6% for subsolid nodules. The diagnostic accuracy of CT-guided TTFNA in relation to the distance between the nodule and the pleural plane was 95.6% for lesions adhering to the pleura and 83.5% for central ones. The diagnostic accuracy was 84.2% for the pulmonary upper lobe nodules, 85.3% for the lower lobe and 90.9% for those in the lingula and middle lobe. In 75% of false negative and inadequate/insufficient cases the needle was found to lie outside the lesion, after reconstruction of the needle path by MPR.

Conclusions

The positive predictive factors of CT-guided TTFNA are related to the nodule size, density and distance from the pleural plane. The most common negative predictive factor of CT-guided TTFNA is the wrong position of the needle tip, as observed in the sagittal and axial oblique sections of the MPR reconstructions. The diagnostic accuracy of CT-guided TTFNA can therefore be improved by using the MPR technique to plan the needle path during the FNA procedure.     

Atypical appendicitis: diagnostic value of volume-rendered reconstructions obtained with 16-slice multidetector-row CT

Purpose

This study was done to assess the possible clinical value of volume-rendered (VR) and curved volume-rendered (cVR) reconstructions obtained from isotropic data in the diagnosis of atypical appendicitis.

Materials and methods

Forty-five patients with suspected acute appendicitis were examined with 16-slice multidetector computed tomography (MDCT) before and after contrast material injection. A diagnosis of atypical appendicitis was made in 33 cases. Two independent blinded radiologists with 2 and 9 years of CT experience assessed the axial scans and 2 months later the VR and cVR reconstructions. The following parameters were considered: presence, location, and wall thickness of the appendix; wall enhancement; distension; periappendiceal fat attenuation; presence of appendicolith; and free air and/or periappendiceal fluid collections. Sensitivity, specificity, and diagnostic accuracy values were calculated for each reader. The concordance between the two radiologists was analysed by using Cohen’s kappa statistic.

Results

Mean sensitivity, specificity and accuracy for the less experienced radiologist were, respectively, 82%, 91% and 84% for the axial scans and 94%, 91% and 93% for the VR and cVR images, whereas the values for the more experienced reader were 94%, 100% and 95% for axial scans, and 97%, 100% and 98% for VR and cVR images.

Conclusions

In patients with atypical appendicitis, VR and cVR reconstructions increase the accuracy of MDCT in relation to the reader’s experience and reduce the number of false negative results.     

Assessment of pulmonary melanoma metastases with 18F-FDG PET/CT: which PET-negative patients require additional tests for definitive staging?

Objectives

To determine, in patients with melanoma, the dependence of PET sensitivity on pulmonary metastasis size, and to determine patients who require further evaluation for definite staging.

Methods

Of 183 melanoma patients who underwent ¹⁸F-fluorodeoxyglucose PET/computed tomography (CT) for staging or follow-up between January 2008 and June 2011, 38 patients (18 women and 20 men; mean age 62.0?±?14.7?years) with one or more pulmonary metastases visible on CT were included in the retrospective study. Each pulmonary metastasis was rated as positive or negative on PET, and lesion size (maximum transverse diameter) was assessed on CT. PET sensitivity was calculated according to the lesions’ size, in 2-mm steps.

Results

A total of 181 pulmonary metastases were analysed. PET sensitivity was 7.9?% for lesions of 4–5?mm; 33.3?% for lesions of 6–7?mm; 56.8?% for lesions of 8–9?mm; 63.6?% for lesions of 10–11?mm; 100?% for lesions of 12–14?mm; and 100?% for lesions of at least 15?mm. The differences in sensitivity between the size groups were significant (P?<?0.001)

Conclusions

With current state-of-the-art PET/CT technology, additional tests are necessary for definitive staging of melanoma patients who have one or more PET-negative lung nodules less than 12?mm in diameter on expiratory CT.

Key Points

? PET cannot rule out malignancy in pulmonary nodules less than 12?mm on expiratory CT. ? Melanoma patients with PET-negative pulmonary nodules less than 12?mm require additional tests. ? Knowledge of these factors can help interpretation of PET and PET/CT findings.     

Comparison between 2D and 3D computed tomography evaluation of glenoid bone defect in unilateral anterior gleno-humeral instability

Purpose

This study evaluated the agreement between 2D and 3D computed tomography (CT) measurements in identifying the size and type of glenoid-bone defect in anterior glenohumeral instability.

Materials and methods

One hundred patients affected by unilateral anterior glenohumeral instability underwent a CT of both shoulders. Images were processed with both 2D [multiplanar reconstruction (MPR)] and 3D [volumerendering (VR)] methods. The area of the missing glenoid was calculated in comparison with the healthy glenoid and expressed as a percentage. Agreement between the two measurements was assessed according to the Bland-Altman method; a 5% mean difference was considered as clinically relevant.

Results

Analysis of agreement between MPR and VR measurements of the percentage of missing glenoid showed a mean difference equal to 0.62%±1.96%. Percent agreement between the two measurements in detecting the presence of bone defect was 97% (p<0.0001). Percent agreement between the two measurements in discriminating the type of bone defect was 97% (p<0.0001).

Conclusions

Agreement between 2D (MPR) and 3D (VR) CT measurements to identify the size and type of glenoid-bone defect in anterior glenohumeral instability was so high that the two measurements can be considered interchangeable.     

Optimal image reconstruction for detection and characterization of small pulmonary nodules during low-dose CT

Objectives

To optimize the slice thickness/overlap parameters for image reconstruction and to study the effect of iterative reconstruction (IR) on detectability and characterization of small non-calcified pulmonary nodules during low-dose thoracic CT.

Materials and methods

Data was obtained from computer simulations, phantom, and patient CTs. Simulations and phantom CTs were performed with 9 nodules (5, 8, and 10 mm with 100, ?630, and ?800 HU). Patient data were based on 11 ground glass opacities (GGO) and 9 solid nodules. For each analysis the nodules were reconstructed with filtered back projection and IR algorithms using 10 different combinations of slice thickness/overlap (0.5–5 mm). The attenuation (CT#) and the contrast to noise ratio (CNR) were measured. Spearman’s coefficient was used to correlate the error in CT# measurements and slice thickness. Paired Student’s t test was used to measure the significance of the errors.

Results

CNR measurements: CNR increases with increasing slice thickness/overlap for large nodules and peaks at 4.0/2.0 mm for smaller ones. Use of IR increases the CNR of GGOs by 60 %. CT# measurements: Increasing slice thickness/overlap above 3.0/1.5 mm results in decreased CT# measurement accuracy.

Conclusion

Optimal detection of small pulmonary nodules requires slice thickness/overlap of 4.0/2.0 mm. Slice thickness/overlap of 2.0/2.0 mm is required for optimal nodule characterization. IR improves conspicuity of small ground glass nodules through a significant increase in nodule CNR.

Key Points

? Slice thickness/overlap affects the accuracy of pulmonary nodule detection and characterization. ? Slice thickness ≥3 mm increases the risk of misclassifying small nodules. ? Optimal nodule detection during low-dose CT requires 4.0/2.0-mm reconstructions. ? Optimal nodule characterization during low-dose CT requires 2.0/2.0-mm reconstructions. ? Iterative reconstruction improves the CNR of ground glass nodules by 60 %.     

Sensitivity and accuracy of volumetry of pulmonary nodules on low-dose 16- and 64-row multi-detector CT: an anthropomorphic phantom study

Objective

To assess the sensitivity of detection and accuracy of volumetry by manual and semi-automated quantification of artificial pulmonary nodules in an anthropomorphic thoracic phantom on low-dose CT.

Methods

Fifteen artificial spherical nodules (diameter 3, 5, 8, 10 and 12?mm; CT densities -800, -630 and +100 HU) were randomly placed inside an anthropomorphic thoracic phantom. The phantom was examined on 16- and 64-row multidetector CT with a low-dose protocol. Two independent blinded observers screened for pulmonary nodules. Nodule diameter was measured manually, and volume calculated. For solid nodules (+100 HU), diameter and volume were also evaluated by semi-automated software. Differences in observed volumes between the manual and semi-automated method were evaluated by a t-test.

Results

Sensitivity was 100?% for all nodules of >5?mm and larger, 60?C80?% for solid and 0?C20?% for non-solid 3-mm nodules. No false-positive nodules but high inter-observer reliability and inter-technique correlation were found. Volume was underestimated manually by 24.1?±?14.0?% for nodules of any density, and 26.4?±?15.5?% for solid nodules, compared with 7.6?±?8.5?% (P?<?0.01) semi-automatically.

Conclusion

In an anthropomorphic phantom study, the sensitivity of detection is 100?% for nodules of >5?mm in diameter. Semi-automated volumetry yielded more accurate nodule volumes than manual measurements.

Key Points

? Computed tomography has become the definitive investigation of the chest. ? Low-dose CT techniques have recently been introduced. ? Low-dose CT is reliable for detecting spherical pulmonary nodules of >5?mm. ? Semi-automated volumetry is more accurate than manual measurement for pulmonary nodules. ? No difference in the accuracy of volumetry was found between 16- and 64- MDCT.     

Assessment of ureteric obstruction with 16-MDCT: Curved planar reformats versus three-dimensional volume-rendered images and their corresponding maximum intensity projections

Aim

To compare the sensitivity and diagnostic accuracy of curved planar reformation (CPR) image on the one hand versus combined volume-rendered (VR) image and its corresponding maximum intensity projection (MIP) image on the other hand for determination of the cause and level of ureteral obstruction.

Materials and methods

The study included 60 patients with clinical and sonographic manifestations of ureteral obstruction who underwent two-phase multidetector CT urography (MDCTU) using a 16-slice machine. A total of 82 ureters were examined. CPR images were performed to display the entire course of ureters in the same image. 3D VR reformats and their corresponding MIP were used to enhance visualization of opacified ureters. The sensitivity and accuracy of CPR, and combined 3D VR and MIP for diagnosis of ureteral obstruction were calculated and compared in reference to the gold standard.

Results

The cause of ureteral obstruction was calculous in 28/82 ureters (34.14%), and noncalculous in 50/82 (61%). The lower third ureter was the most affected level in 48/82 ureters (58.5%). The total sensitivity and accuracy of CPR for the cause of the ureteric obstruction (97.5% and 95.3%, respectively) were higher than those of 3D VR and its corresponding MIP (75% and 73.2%, respectively). CPR also was more sensitive and accurate (total sensitivity of 100% and accuracy of 100%) compared with those of combined 3D VR and its corresponding MIP (79.5% and 75.9%, respectively) for the level of ureteral obstruction.

Conclusions

CPR had superior diagnostic accuracy than 3D VR and MIP in detecting the cause and level of ureteral obstruction.     

Computer-assisted solid lung nodule 3D volumetry on CT: influence of scan mode and iterative reconstruction: a CT phantom study

Objective

To evaluate the effect of high-resolution scan mode and iterative reconstruction on lung nodule 3D volumetry.

Methods

Solid nodules with various sizes (5, 8, 10 and 12 mm) were placed inside a chest phantom. CT images were obtained with various tube currents, scan modes (conventional mode, high-resolution mode) and iterative reconstructions [0, 50 and 100 % blending of adaptive statistical iterative reconstruction (ASiR) and filtered back projection]. The nodule volumes were calculated using semiautomatic software and compared with the assumed volume from the nodules.

Results

The mean absolute and relative percentage error improved when using iterative reconstruction especially when using the conventional scan mode; however, this effect was not significant. Significant reduction in volume overestimation was observed when using high-resolution scan mode (P = 0.011).

Conclusion

The high-resolution mode significantly reduces the volume overestimation of 3D volumetry. Iterative reconstruction shows a reduction in volume overestimation and error margin especially with the conventional scan mode; however, this effect was not significant.     

Biliary anatomy on 3D MRCP: Comparison of volume‐rendering and maximum‐intensity‐projection algorithms

Purpose

To compare volume‐rendering (VR) and maximum‐intensity‐projection (MIP) of three‐dimensional T2‐weighted turbo spin‐echo magnetic resonance cholangiopancreatography using a free‐breathing navigator‐triggered prospective acquisition correction (3D‐TSE‐PACE‐MRCP) to define biliary anatomies.

Materials and Methods

VR and MIP images of 3D‐TSE‐PACE‐MRCP for 102 patients were retrospectively evaluated. Interpretation of cystic duct variation and biliary branching patterns of each image were recorded independently by two radiologists in a blinded fashion. Interpretation confidence on a five‐point scale was compared using the Wilcoxon signed‐rank test. The McNemar test was used to compare the accuracies of each reformation with the reference standard obtained by consensus interpretation of both the images and source images.

Results

The reference standard identified all biliary bifurcations and 95 of 102 cystic duct confluences (93.1%). VR findings agreed with the reference standard findings more often than MIP with regard to cystic duct variation (94 [92.2%] vs. 76 [74.5%], P < 0.01) while there was no significant difference for biliary branching patterns (99 [97.1%] vs. 92 [90.2%], P = 0.092). The mean confidence score was significantly higher with VR than MIP with regard to both cystic duct variation and biliary branching patterns (3.7 vs. 2.4; P < 0.01; 4.1 vs. 3.3; P < 0.01).

Conclusion

VR reformation of 3D‐TSE‐PACE‐MRCP defines biliary anatomies more accurately than MIP. J. Magn. Reson. Imaging 2009;29:601–606. © 2009 Wiley‐Liss, Inc.

     

Benefits of 3D technique in guiding percutaneous retroperitoneal biopsies

Purpose

This study aimed to assess the usefulness and advantages of multiplanar reformations (MPR) during multidetector-row computed tomography (MDCT)-guided percutaneous fine-needle aspiration biopsy (FNAB) and core biopsy of retroperitoneal lesions that are difficult to access with the guidance of ultrasound and axial CT alone owing to overlying bony structures, large vessels or abdominal organs.

Materials and methods

MDCT-guided retroperitoneal FNAB and core biopsy was performed on 14 patients with suspected retroperitoneal neoplasm. We used MPR images (sagittal and coronal) obtained with a six-detector-row MDCT scanner and 20?C22 gauge Chiba needles.

Results

Using MDCT with 3D MPR allowed biological samples to be obtained in all cases (ten cytological and four histological) and diagnostic samples in 11/14 cases (78.5%). Histological samples were deemed adequate for diagnostic assessment in all cases and cytological samples in 7/10 cases (70%).

Conclusions

MPR images allowed sampling of retroperitoneal lesions until now considered unreachable with the guidance of axial MDCT alone. Compared with the conventional procedure, the use of MPR images does not increase the procedure time.     

Volumetric thin-section CT: evaluation of pulmonary interlobar fissures

PURPOSE

We aimed to perform an imaging analysis of interlobar fissures and their variations using thin-section computed tomography (CT).

METHODS

Volumetric thin-section CT scanning was performed in 208 subjects. Interlobar fissures were observed on axial images, and reconstructed coronal and sagittal images were observed by multi-planar reformatting (MPR). The vessel distributions were verified by maximal intensity projection (MIP). On the axial images, the interlobar fissures were characterized by lines of hyperattenuation, bands of hyperattenuation, avascular zones, and mixed imaging. The interlobar fissures were divided into seven grades according to the percentage of defects over the entire fissure.

RESULTS

On the axial images, of all interlobar fissures without avascular zones, 70.2% of the right oblique fissures (ROFs) and 94.2% of the left oblique fissures (LOFs) appeared as lines, and 83.2% of the horizontal fissures (HFs) appeared as bands. All of the interlobar fissures appeared as lines on the coronal and sagittal images. Of all cases, 17.8% showed fully complete interlobar fissures for all three fissures. Incomplete fissures included 41.3% of ROFs, 58.2% of HFs, and 45.2% of LOFs. In ROFs and LOFs, discontinuity was most frequently below 20%, while in HFs discontinuity was most frequently 41%–60%. The most common classification of incomplete interlobar fissures was a discontinuous avascular zone.

CONCLUSION

Incomplete interlobar fissures are common variations of interlobar fissures. Techniques including volumetric thin-section CT, MPR, and MIP can assist in the diagnosis of incomplete interlobar fissures.The pulmonary interlobar fissures are important landmarks for pulmonary anatomy. They adopt a double membrane structure formed by invagination of the visceral pleura. The interlobar fissures are 1–3 mm thick and consist of the right oblique fissure (ROF), horizontal fissure (HF), and left oblique fissure (LOF) (1, 2). The recognition of pulmonary interlobar fissures and their variations is beneficial for identifying pulmonary lesion locations, evaluating disease progression, selecting surgical operations, and applying endoscopic therapy (3–5). With the constant development of imaging techniques, thin-section computed tomography (CT) can provide more detailed information regarding lung structure with respect to the anatomy (5–7). Multiplanar reformatting (MPR) (8) and maximal intensity projection (MIP) are reconstruction techniques based on a noninvasive methodology that detect pulmonary interlobar fissure variations. The results generated by these techniques highly resemble the results of an autopsy (8). In this study, the pulmonary interlobar fissures and their variations were investigated and analyzed by volumetric thin-section MPR and MIP images.     

Performance of computer-aided detection of pulmonary nodules in low-dose CT: comparison with double reading by nodule volume

Objective

To evaluate performance of computer-aided detection (CAD) beyond double reading for pulmonary nodules on low-dose computed tomography (CT) by nodule volume.

Methods

A total of 400 low-dose chest CT examinations were randomly selected from the NELSON lung cancer screening trial. CTs were evaluated by two independent readers and processed by CAD. A total of 1,667 findings marked by readers and/or CAD were evaluated by a consensus panel of expert chest radiologists. Performance was evaluated by calculating sensitivity of pulmonary nodule detection and number of false positives, by nodule characteristics and volume.

Results

According to the screening protocol, 90.9?% of the findings could be excluded from further evaluation, 49.2?% being small nodules (less than 50?mm³). Excluding small nodules reduced false-positive detections by CAD from 3.7 to 1.9 per examination. Of 151 findings that needed further evaluation, 33 (21.9?%) were detected by CAD only, one of them being diagnosed as lung cancer the following year. The sensitivity of nodule detection was 78.1?% for double reading and 96.7?% for CAD. A total of 69.7?% of nodules undetected by readers were attached nodules of which 78.3?% were vessel-attached.

Conclusions

CAD is valuable in lung cancer screening to improve sensitivity of pulmonary nodule detection beyond double reading, at a low false-positive rate when excluding small nodules.

Key Points

? Computer-aided detection (CAD) has known advantages for computed tomography (CT). ? Combined CAD/nodule size cut-off parameters assist CT lung cancer screening. ? This combination improves the sensitivity of pulmonary nodule detection by CT. ? It increases the positive predictive value for cancer detection.     

Diagnostic accuracy of translucency rendering to differentiate polyps from pseudopolyps at 3D endoluminal CT colonography: a feasibility study

Purpose

The aim of this study was to assess the accuracy of translucency rendering (TR) in computed tomographic (CT) colonography without cathartic preparation using primary 3D reading.

Materials and methods

From 350 patients with 482 endoscopically verified polyps, 50 pathologically proven polyps and 50 pseudopolyps were retrospectively examined. For faecal tagging, all patients ingested 140 ml of orally administered iodinated contrast agent (diatrizoate meglumine and diatrizoate sodium) at meals 48 h prior to CT colonography examination and two h prior to scanning. CT colonography was performed using a 64-section CT scanner. Colonoscopy with segmental unblinding was performed within 2 weeks after CT. Three independent radiologists retrospectively evaluated TRCT clonographic images using a dedicated software package (V3D-Colon System). To enable size-dependent statistical analysis, lesions were stratified into the following size categories: small (≤5 mm), intermediate (6–9 mm), and large (≥10 mm).

Results

Overall average TR sensitivity for polyp characterisation was 96.6%, and overall average specificity for pseudopolyp characterisation was 91.3%. Overall average diagnostic accuracy (area under the curve) of TR for characterising colonic lesions was 0.97.

Conclusions

TR is an accurate tool that facilitates interpretation of images obtained with a primary 3D analysis, thus enabling easy differentiation of polyps from pseudopolyps.     

HRCT in detection of pulmonary infections from nontuberculous mycobacteria: personal experience

Purpose

The authors sought to assess the role of highresolution computed tomography (HRCT) in the detection and follow-up of nontuberculous mycobacteria (NTM) pulmonary infection in immunocompetent patients and to identify the most common radiological patterns for diagnosis.

Materials and methods

Plain chest radiographs and HRCT scans of 42 consecutive patients with NTM pulmonary infection (M/F 26/16; mean age 57, range 41–83) were retrospectively reviewed. Ten of these patients were followed up for 18 months after diagnosis. Small nodules (<10 mm), nodules 10- to 30-mm in diameter, lobar/segmental consolidation, cavitations, bronchiectasis and tree-in-bud pattern were analysed.

Results

Small nodules were more frequent than nodules 10- to 30-mm in diameter, and segmental consolidation was more frequent than lobar. Cavitations, tree-in-bud and bronchiectasis were more frequently located in the upper lobes. Four of the followed-up patients had cavitation of preexisting nodules, and five had progression of bronchiectasis.

Conclusions

HRCT allows accurate detection and followup of the most frequent presentation patterns: diffuse small nodules, bronchiectasis, upper lobe segmental consolidation and cavitations. The appearance of new bronchiectasis and progression of old disease are due to pulmonary infection.     

Gadoxetic acid-enhanced MRI for hepatocellular carcinoma and hypointense nodule observed in the hepatobiliary phase

Purpose

The aim of our study was to evaluate the diagnostic accuracy of gadoxetic acid-enhanced magnetic resonance (MR) imaging both in the detection of hepatocellular carcinoma (HCC) and precancerous lesions and in the assessment of their evolution.

Materials and methods

A retrospective study was undertaken on 56 patients with chronic liver disease and suspected liver lesions. We evaluated the number, size and signal intensity of the nodules on dynamic and hepatobiliary MR images. Follow-up studies were carried out every 3 months. Statistical analysis was performed using the Fisher’s exact test.

Results

A total of 120 nodules were identified in 41 patients. Of these, 92/120 nodules (76.6 %; mean diameter 18.4 mm) showed the typical HCC vascular pattern: 90/92 nodules appeared hypointense and 2/92 were hyperintense on hepatobiliary phase images. An additional 28/120 hypointense, nonhypervascular nodules (23.3 %; mean diameter 11 mm) were detected on hepatobiliary phase images, 15 of which showed hypointensity also on the equilibrium phase images. During the 3- to 12-month follow-up, 14/28 nodules (mean diameter 13.3 mm) developed the typical vascular pattern of HCC.

Conclusions

Gadoxetic acid-enhanced MR imaging is useful for detecting HCC as well as hypovascular nodules with potential progression to HCC. Lesions measuring more than 10 mm in diameter are at higher risk of developing into HCC (p = 0.0128).     

Metal artefact reduction from dental hardware in carotid CT angiography using iterative reconstructions

Purpose

To determine the value of a metal artefact reduction (MAR) algorithm with iterative reconstructions for dental hardware in carotid CT angiography.

Methods

Twenty-four patients (six of which were women; mean age 70?±?12 years) with dental hardware undergoing carotid CT angiography were included. Datasets were reconstructed with filtered back projection (FBP) and using a MAR algorithm employing normalisation and an iterative frequency-split (IFS) approach. Three blinded, independent readers measured CT attenuation values and evaluated image quality and degrees of artefacts using axial images, multi-planar reformations (MPRs) and maximal intensity projections (MIP) of the carotid arteries.

Results

CT attenuation values of the internal carotid artery on images with metal artefacts were significantly higher in FBP (324?±?104HU) datasets compared with those reconstructed with IFS (278?±?114HU; P?<?0.001) and with FBP on images without metal artefacts (293?±?106HU; P?=?0.006). Quality of IFS images was rated significantly higher on axial, MPR and MIP images (P?<?0.05, each), and readers found significantly less artefacts impairing the diagnostic confidence of the internal carotid artery (P?<?0.05, each).

Conclusion

The MAR algorithm with the IFS approach allowed for a significant reduction of artefacts from dental hardware in carotid CT angiography, hereby increasing image quality and improving the accuracy of CT attenuation measurements.

Key points

? CT angiography of the neck has proven value for evaluating carotid disease ? Neck CT angiography images are often degraded by artefacts from dental implants ? A metal artefact reduction algorithm with iterative reconstruction reduces artefacts significantly ? Visualisation of the internal carotid artery is improved     

Preoperative vascular mapping with multislice CT of deep inferior epigastric artery perforators in planning breast reconstruction after mastectomy

Purpose

Our aim was to evaluate the usefulness of computed tomography angiography (CTA) in vascular mapping for planning breast reconstruction after mastectomy using a free flap made with the deep inferior epigastric perforators (DIEP).

Materials and methods

We retrospectively evaluated 41 patients, mean age 57 years, scheduled for mastectomy. CTA was performed with a 64-row scanner (Aquilion 64, Toshiba Medical Systems, Japan), with injection of 100 ml of contrast medium (iomeprol 350 mgI/ml, Bracco, Italy) at 4.5 ml/s. Maximum intensity projection (MIP) and threedimensional volume-rendering (VR) reconstructions were made to mark perforator positions. Presentation frequency, anatomy and artery opacification quality were evaluated.

Results

DIEP were always depicted (n=81) and subdivided according to Taylor’s classification into type I (65%), type II (28%), and type III (7%). We observed a mean of three (range, 1–5) DIEP arteries on the right and two (range, 1–5) on the left side. The superficial inferior epigastric artery (SIEA) was depicted in 6/41 patients, bilaterally in three cases. Opacification was optimal in 30/41 cases, venous contamination due to late arterial phase in eight and low opacification due to early scan in three.

Conclusions

Studying DIEP with CTA is useful in the surgical planning of breast reconstruction, even though it requires careful optimisation owing to the critical timing of opacification typical of that vascular district.     

Mycobacterium kansasii pulmonary infection: CT findings in 29 cases

Purpose

Our aim was to assess computed tomography (CT) features of Mycobacterium kansasii pulmonary infection (M. kansasii infection).

Materials and methods

A total of 29 cases confirmed to have M. kansasii infections were analyzed. The main locations of pulmonary changes, incidence, and various imaging features of the cavity (location, maximum diameter, wall thickness, satellite nodules, intracavitary fluid), and other imaging findings such as nodules, consolidation, and bronchiectasis, were visually assessed on CT images.

Results

Locations of the main abnormalities were as follows: right S2 41%; right S1 31%; left S1+S2 2: 21%. A total of 49 cavities were observed in 24 (83%) cases. The mean maximum diameter, wall thickness, and ratio of wall thickness to the maximum diameter were 33.0?mm, 4.7?mm, and 0.19, respectively. Shapes of the cavities were round in nine (18.4%), oval in 17 (34.7%), and tubular/meandering in 23 (47%). Satellite nodules were found in only 30.6% of patients (n?=?15). Small nodules were found in 26 (89.7%) patients, and most of them showed a centrilobular distribution.

Conclusion

The characteristic CT findings suggestive of M. kansasii infection include cavities located in the right posterior or apical segment with a tubular/meandering shape and a thin wall.     

Application of multislice detector spiral computed tomography to intracranial aneurysms: first clinical experience

Purpose. To identify advantages when using the new multislice spiral CT technology (MSCT) for the detection and demonstration of intracranial aneurysms with CT angiography (CTA)? Material and methods. Patients with suspected intracranial aneurysms underwent 4- and 8-slice spiral CTA. Image postprocessing included “maximum intensity projection” (MIP),“volume rendering” (VR) and additionally curved multiplanar reconstructions (MPR) for aneurysms suspected at the carotid siphon.The results were compared with those achieved with digital subtraction angiography (DSA). Results. In 19 patients 21 out of 22 aneurysms were detected by CTA. A high resolution three-dimensional view of the aneurysm morphology in spatial relation to the surrounding structures was achieved.Further information could be gained by making a detailed examination of the inside wall of the aneurysm, using virtual vascular 3D-endoscopy and virtual 3D-craniotomy. Conclusion. Compared to DSA,MS-CTA is a useful additional and in selected cases alternative modality for the detection with marked advantages in the demonstration of intracranial aneurysms.     

Oblique approach for CT-guided liver radiofrequency ablation using multiplanar reformation images in hepatocellular carcinoma

Purpose

To evaluate the feasibility and safety of CT-guided radiofrequency (RF) ablation by caudal-cranial oblique insertion using multiplanar reformation (MPR) images for hepatocellular carcinomas (HCCs).

Materials and methods

Twenty-two HCCs in 19 patients that were difficult to demonstrate on ultrasound (mean tumor diameter was 17.5?mm) were treated with CT-guided RF ablation by caudal-cranial oblique insertion to avoid pneumothorax, using MPR images after transcatheter arterial chemoembolization. The insertion point and direction of insertion, avoiding aerated lung parenchyma, bones, large vessels, and intestine, were sought on the MPR images. Technical success was defined as complete eradication of tumor enhancement in the contrast-enhanced CT. Local tumor progression was defined by the appearance of enhanced tumor adjacent to the zone of ablation. The technical success rate, local tumor progression, and complications were investigated.

Results

The coronal plane was used for insertion in 18 tumors, the sagittal plane in 3 tumors, and the oblique plane in 1 tumor. RF electrode placement was successful and complete necrosis was obtained in all cases. During the mean follow-up period of 38.0?months, local tumor progression was not detected in any of the patients. There were no major complications, including pneumothorax.

Conclusion

CT-guided RF ablation by caudal-cranial oblique insertion using MPR images is a feasible and safe therapeutic option.