Multisection CT: scanning techniques and clinical applications

Visualization of the segment IV hepatic artery using 128-section MDCT angiography

AIM

To visualize the segment IV hepatic artery and to evaluate the variations in anatomy using multidetector computed tomography (MDCT) angiography.

MATERIALS AND METHODS

Six hundred and seventeen patients (381 men and 236 women; mean age 62.7 ± 8.1 years; age range 22-92 years) who underwent MDCT angiography performed using a 128-section MDCT system were included in the study. The segment IV hepatic arteries of 453 patients with adequate image quality were displayed using volume rendering (VR), maximum intensity projection (MIP), and multiplanar reconstruction (MPR), and were analysed regarding the origination and variation of the arteries by two radiologists and an anatomist retrospectively.

RESULTS

Segment IV arteries were categorized into five different types according to their points of origin: left hepatic artery (LHA, 51.66%), right hepatic artery (RHA, 30.68%), proper hepatic artery (PHA, 5.3%), dual (12.14%), and triple (0.22%). Segment IV arteries arising from normal LHA, RHA, and PHA were found in 73.73% of patients, and those arising from variant LHA or RHA were found in 26.27%. The patterns RN2, LA2, LA3, LA4, PN2, PV1, DA1, DA2, DV3, and DV4 were first reported in the present study.

CONCLUSIONS

MDCT angiography can evaluate normal as well as anatomical variants of segment IV arteries. Predicting arterial patterns of segment IV of the liver is important in planning and performing all radiological and surgical procedures in the liver, especially in hemi-liver graft procedures.

MDCT of Small Bowel Obstruction: How Reliable Are Oblique Reformatted Images in Localizing Point of Transition?

The goal of this study is to prospectively assess the additional value of oblique reformatted images for localizing POT, having surgery as a reference standard. Materials and Methods. 102 consecutive patients with suspected small bowel obstruction (SBO) underwent 64-slice multidetector row CT (MDCT) using surgical findings as reference standard. Two independent GI radiologists reviewed the CT scans to localize the exact POT by evaluating axial images (data set A) followed by axial, coronal, and oblique MPR images. CT findings were compared to surgical findings in terms of diagnostic performance. McNemar's test was used to detect any statistical difference in POT evaluation between datasets A and B. Kappa statistics were applied for measuring agreement between two readers. Results. There was a diagnostic improvement of 9.9% in the case of the less experienced radiologist in localizing POT by using oblique reformatted images. The more experienced radiologist showed diagnostic improvement by 12.9%.

Reliability of preoperative multidetector computed tomography scan in patients with chronic otitis media

OBJECTIVE

The objectives of this study were to specify the objective criteria of existence of cholesteatoma in chronic otitis media on the preoperative multidetector computed tomography (MDCT) and to evaluate the complications of disease.

METHODS

We compared the results of preoperative MDCT scan with intraoperative findings in 71 patients (22 women, 49 men; mean age, 16-73 years) who had mastoidectomy operation between January 2008 and May 2012. Multidetector computed tomography evaluations of temporal bone were performed on a workstation using high-spatial-resolution magnified images with intended angle and plane.

RESULTS

We observed cholesteatoma formation in all patients with scutum erosion (n = 11), dural exposure (n = 6), and lateral semicircular canal fistula (n = 5). Computed tomography revealed these findings with 100% sensitivity. Distortion of ossicular integrity (n = 11) and facial canal dehiscence (n = 5) was significantly higher in cholesteatoma patients. Using the criteria of osteolysis, the sensitivity, specificity, and the accuracy rates of MDCT in detecting cholesteatoma were 71%, 93%, and 88%, respectively. The best diagnostic clue of a cholesteatoma was a mass-like soft tissue located in a retraction pocket in the posterosuperior quadrant of the Shrapnell membrane, causing widening of Prussak space and scutum erosion. Evaluation of computed tomography scan showed nearly 100% sensitivity in detecting tympanic opacification, dural height, dehiscence of lateral semicircular canal, tegmen tympani erosion, and deformation of malleoincudal articulation. However, its contribution to detecting minor ossicular erosion, facial canal dehiscence, and incudostapedial joint evaluation was limited.

CONCLUSIONS

Preoperative assessment of chronic otitis media via MDCT with intended angle and plane produces important guidance to understand the extent of disease and to prevent possible intraoperative complications.

Imaging of Cystic and Cyst-like Lesions of the Mediastinum with Pathologic Correlation

Cystic masses of the mediastinum are a heterogenous group of asymptomatic or symptomatic, congenital, infectious, or neoplastic lesions. For early and correct diagnosis, evaluation, and optimal patient management of cystic mediastinal masses in infants, children, or adults imaging plays an important role. A non-invasive and sensitive imaging modality is an efficient and cost-effective tool. Multidetector computed tomography (MDTC) with volumetric acquisition provides fast acquisition of high resolution images and multiplanar reconstruction. Both 2D and 3D imaging in mediastinal imaging help in surgical planning and assessing resectability of mediastinal lesions. MR imaging has many advantages over other modalities for detecting and identifying cystic, or fluid-filled mediastinal masses, because of its intrinsic high soft tissue contrast and direct multiplanar imaging capabilities. However, histological tissue analysis may be required to differentiate a cystic lesion from other cyst-like or low-attenuation lesions.

Experimental study and optimization of scan parameters that influence radiation dose in temporal bone high-resolution multidetector row CT

BACKGROUND AND PURPOSE

MDCT has some specific scan parameters that may systematically increase or decrease radiation dose to patients. This study explored the scan protocol parameters that impact radiation dose in temporal bone MDCT and determined the optimal scan parameters that balance radiation dose with diagnostic image quality.

MATERIALS AND METHODS

Using exsomatized cadaveric heads, traditional axial scanning, and helical scanning were performed with different detector collimations. Helical scans of the same scan region were then acquired by using the determined optimal detector collimation and various tube voltages, whereas other scan parameters remained fixed. Next, the scans were repeated by using various tube current-time products by using the determined optimal tube voltage. Last, with fixed tube current-time product, the scans were repeated with various pitches. All thin-section, helically acquired scans were reformatted to axial and coronal images with respect to the relevant scanning baseline. In each of the image volumes, the mean and SD HU values in regions of interest were measured in the central section of the internal auditory canal, and CNR values were calculated.

RESULTS

In agreement with theory, wider detector collimations such as 16 × 0.625 mm and 64 × 0.625 mm were associated with lower radiation doses than narrower collimations due to their lower overbeaming and higher geometric efficiency. In helical scanning, the detector collimation of 16 × 0.625 mm had higher image quality and the minimum DLP. Axial and coronal images acquired by using a 140-kVp tube voltage had significantly lower noise than scans acquired at 120 or 80 kVp with equivalent volume CT dose index. Diagnostic image quality was achieved when using a minimum tube current-time product of 120 mAs. Noise, CNR, and dose were jointly optimized with a pitch of 0.685.

CONCLUSIONS

Temporal bone CT scanning parameters may be optimized by following a systematic procedure that allows for the optimization of diagnostic image quality and the minimization of radiation dose. One such procedure for a particular 64-section MDCT scanner has been presented.

Bladder trauma: multidetector computed tomography cystography

Multidetector computed tomography (MDCT) cystography is rapidly becoming the most recommended study for evaluation of the bladder for suspected trauma. This article reviews the bladder trauma with emphasis on the application of MDCT cystography to traumatic bladder injuries using a pictorial essay based on images collected in our level I trauma center.

Glenohumeral joint instability

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician.

Do characteristics of pulmonary nodules on computed tomography in children with known osteosarcoma help distinguish whether the nodules are malignant or benign?

PURPOSE

To determine if selected computed tomography (CT) characteristics of pulmonary nodules in pediatric patients with osteosarcoma can help distinguish the nodules as benign or malignant.

METHODS

The institutional review board approved this HIPAA (Health Insurance Portability and Accountability Act-compliant, retrospective study of 30 pediatric osteosarcoma patients (median age 14 years, range 8-22) who underwent chest CT with resection of 117 pulmonary nodules from January 2001 to December 2006. Two pediatric radiologists and one chest radiologist independently and retrospectively reviewed the CT scans and classified nodules as benign, malignant, or indeterminate on the basis of nodule size, laterality, number, location, growth, density, margin appearance, and calcification. Generalized estimating equations were used to examine which characteristics were independent predictors of nodule malignancy.

RESULTS

Of the 117 nodules, 80 (68%) were malignant and 37 (32%) were benign by pathologic review. The readers correctly classified 93% to 94% of the malignant nodules. For benign lesions, the results were not as accurate, with the readers correctly classifying only 11% to 30% of lesions. Most of the benign lesions were classified as indeterminate by the readers (54%-65%). Nodule size (≥5 mm) and the presence of calcifications were associated with an increased probability of malignancy (P b .05).

CONCLUSION

On chest CT, nodule size 5 mm or greater and the presence of calcifications are associated with an increased probability of malignant nodule histology in pediatric patients with osteosarcoma. However, nodule characteristics, apart from size and calcification, at chest CT cannot reliably distinguish benign from malignant pulmonary nodules in these patients.

Adult patient radiation doses from non-cardiac CT examinations: a review of published results

OBJECTIVES

CT is a valuable tool in diagnostic radiology but it is also associated with higher patient radiation doses compared with planar radiography. The aim of this article is to review patient dose for the most common types of CT examinations reported during the past 19 years.

METHODS

Reported dosimetric quantities were compared with the European diagnostic reference levels (DRLs). Effective doses were assessed with respect to the publication year and scanner technology (i.e. single-slice vs multislice).

RESULTS

Considerable variation of reported values among studies was attributed to variations in both examination protocol and scanner design. Median weighted CT dose index (CTDI(w)) and dose length product (DLP) are below the proposed DRLs; however, for individual studies the DRLs are exceeded. Median reported effective doses for the most frequent CT examinations were: head, 1.9 mSv (0.3-8.2 mSv); chest, 7.5 mSv (0.3-26.0 mSv); abdomen, 7.9 mSv (1.4-31.2 mSv); and pelvis, 7.6 mSv (2.5-36.5 mSv).

CONCLUSION

The introduction of mechanisms for dose reduction resulted in significantly lower patient effective doses for CT examinations of the head, chest and abdomen reported by studies published after 1995. Owing to the limited number of studies reporting patient doses for multislice CT examinations the statistical power to detect differences with single-slice scanners is not yet adequate.

Adaptive statistical iterative reconstruction technique for pulmonary CT: image quality of the cadaveric lung on standard- and reduced-dose CT

RATIONALE AND OBJECTIVES

To evaluate thin-section computed tomography (CT) images of the lung reconstructed using adaptive statistical iterative reconstruction (ASIR) on standard- and reduced-dose CT.

MATERIALS AND METHODS

Eleven cadaveric lungs were scanned by multidetector-row CT with two different tube currents (standard dose, 400 mA; reduced dose, 10 mA). The degree of ASIR was classified into six different levels: 0% (non-ASIR), 20%, 40%, 60%, 80%, and 100% (maximum-ASIR). The ASIR (20%, 60%, and 100%) images were compared with the ASIR (0%) images and assessed visually by three independent observers for image quality using a 7-point scale. The evaluation items included abnormal CT findings, normal lung structures, and subjective visual noise. The median scores assigned by the three observers were analyzed statistically. Quantitative noise was calculated by measuring the standard deviation in a circular region of interest on each selected image of ASIR (0%-100%).

RESULTS

On standard-dose CT, the overall image quality significantly improved with increasing degree of ASIR (P ≤ .009, Wilcoxon signed-ranks test with Bonferroni correction). As ASIR increased, however, intralobular reticular opacities and peripheral vessels tended to be obscure. On reduced-dose CT, the overall image quality of ASIR (100%) was significantly better than that of ASIR (20%) (P ≤ .009). As ASIR increased, however, intralobular reticular opacities tended to be obscure. Using ASIR significantly reduced subjective and quantitative image noise on both standard- and reduced-dose CT (P < .001, Bonferroni/Dunn's method).

CONCLUSION

ASIR improves the image quality by decreasing image noise. Maximum-ASIR may be needed for improving image quality on highly reduced-dose CT. However, excessive ASIR may obscure subtle shadows.

Multislice CT in congenital bronchopulmonary malformations in children

Congenital bronchopulmonary malformations encompass a wide spectrum of pathologies involving the lungs, trachea and bronchi, pulmonary vessels, and oesophagus. These developmental lesions are often isolated, but the association of two or more anomalies is not infrequent. Contrast-enhanced multidetector computed tomography (MDCT), thanks to multiplanar and 3D reconstructions, allows for detailed studies of these malformations, achieving better accuracy compared with conventional techniques such as chest X-ray, fluoroscopy, ventilation and perfusion scintigraphy and ultrasonography. MDCT is characterised by fast data acquisition and does not require sedation in the majority of cases. The main drawbacks of MDCT are the use of ionising radiation and - in many cases -contrast media. Recently, improved CT scanners and optimised CT protocols have made available to children all the benefits of MDCT, thanks to a significant reduction in radiation dose and an improved risk-benefit ratio. The aim of our paper was to evaluate MDCT in children with bronchopulmonary malformations by reporting our experience (about 2,400 studies in 30 months with a 64-slice MDCT scanner) and comparing it with the available literature.

Update on multidetector computed tomography imaging of the airways

Recent advances in multidetector computed tomography (MDCT) technology have transformed the imaging evaluation of the trachea and bronchi. Multiplanar 2-dimensional and 3-dimensional volume reconstruction techniques, including external rendering and virtual bronchoscopy, can be generated in mere minutes, thereby complementing conventional axial CT imaging in the depiction of various central airway disease processes including airway stenoses, central airway neoplasms, and congenital airway disorders. Paired inspiratory and dynamic expiratory MDCT imaging, along with newer cine CT imaging methods, have enhanced the assessment of tracheobronchomalacia in both adults and the pediatric population. In addition, MDCT imaging plays an essential complementary role to conventional bronchoscopy, facilitating planning and guidance of bronchoscopic interventions, and providing a noninvasive method for postprocedural surveillance.

Battery ingestion in children

INTRODUCTION

Ingestion of batteries by children became more frequent in recent years, due to the increasing accessibility of electronic toys and devices to children. Due to their electrochemical composition, impacted batteries in the esophagus may cause an extensive damage. Following the removal of a battery, the post-esophagoscopy management is still controversial.

CASE PRESENTATION

An otherwise healthy 8 year-old boy presented to the pediatric emergency room 3h after the unintentional swallowing of a lithium battery. On examination, the patient was diaphoretic and tachypneic. Plain PA chest film revealed a 2.5 cm diameter radiopaque round object in the upper esophagus. The patient was scheduled for an urgent rigid esophagoscopy which was performed 2h after admission. Esophagoscopy findings included an impacted lithium battery in an advanced emptying process at a level of 17 cm from the incisor teeth, with a 3rd degree ulcerative esophagitis. It was not possible to visualize either the distal esophagus or the stomach. A nasogastric tube was not inserted because of a significant risk for esophageal perforation if bluntly passed. Post-operative medical therapy included fasting, administration of intravenous antibiotic therapy, antacids, and steroids. Flexible esophagoscopy superior to the level of the mucosal injury performed one day later, revealed erosive esophagitis, without evidence of perforation. Upper digestive tract gastrografin swallow test performed 2 days after esophagoscopy did not demonstrate a leak from the esophagus, and oral feeding was carefully re-initiated. Treatment was discontinued the following day. Follow up on days 10 and 14 revealed a healthy child with normal swallowing.

DISCUSSION

Battery ingestion-related injury results from direct pressure necrosis, local electrical currents and alkali leakage. Signs and symptoms of ingested battery are related to impaction duration, size of battery, battery content and peristaltic waves of the esophagus. Appropriate imaging studies should be performed to maximize identification of the foreign body before esophagoscopy. Esophageal stenting and adjuvant medical therapy (steroid therapy, antibiotic therapy and anti-reflux therapy) have a low evidence level of clinical benefit following caustic injuries from impacted batteries and spillage of their content to the esophagus. A judicious management should be tailored in each patient. Increased public and health personnel awareness is necessary to diminish the incidence of battery ingestion.

Multidetector CT of the lung: image quality with garnet-based detectors

PURPOSE

To evaluate the image quality of both standard- and reduced-dose computed tomography (CT) by comparing multidetector CT with garnet-based detectors with multidetector CT with conventional detectors.

MATERIALS AND METHODS

The study was approved by the internal ethics review board. Informed consent was obtained. Eleven cadaveric lungs inflated and fixed by using the Heitzman method were scanned by using both CT with garnet-based detectors and CT with conventional detectors. Tube current was 400 mA for standard-dose and 10 mA for reduced-dose CT, and voltage was 120 kVp. Either normal scan mode with 984 views (conventional and garnet-based detectors) or high-resolution mode with 2496 views was used. Image quality at conventional-detector CT and garnet-based-detector CT in all modes was graded by two independent observers with a five-point scale. The evaluation items included normal lung structures, subjective visual noise, and abnormal CT findings. Quantitative image noise measurements were calculated by measuring the standard deviations in a circular region of interest on each selected image.

RESULTS

At standard-dose CT, image quality at CT with garnet-based detectors (high-resolution mode) was significantly improved (P < .001, Tukey-Kramer). However, there was no significant difference between quantitative image noise measurements (P > or = .24). At reduced-dose CT, only noise differed significantly, with both subjective visual noise and quantitative image noise measurements significantly greater at CT with garnet-based detectors (high-resolution mode) (P < or = .01). There was no significant difference in image quality except for noise between conventional-detector CT and garnet-based-detector CT (P > or = .06).

CONCLUSION

The image quality of standard-dose garnet-based-detector CT (high-resolution) was significantly improved. Although highly reduced-dose garnet-based-detector CT (high-resolution mode) provided more image noise, overall image quality was not different between conventional-detector CT and garnet-based-detector CT.

Violence-related facial trauma: analysis of multidetector computed tomography findings of 727 patients

OBJECTIVES

The multidetector CT (MDCT) findings of facial trauma in victims of interpersonal violence were assessed.

METHODS

All MDCT requests for suspected facial injury during a 62 month period were retrieved; 727 cases met the inclusion criteria. Images were interpreted by two researchers by consensus.

RESULTS

Of the 727 patients (aged 15-86 years old, mean 37), 583 (80.2%) were male and 144 (19.8%) female. Of all the patients, 74% had a fracture, and of these 44% had multiple non-contiguous fractures.

CONCLUSIONS

Violence is a very common cause of facial injury. Nasal and orbital fractures predominate. Males are more often involved; they are younger, sustain fractures more often and significantly more often present with high-energy fracture patterns. LeFort fractures are often unilateral or asymmetrical, and are frequently accompanied by other, clinically significant fractures. Up to 25% of patients with fractures do not have paranasal sinus effusions.

Single-phase 16-slice multidetector computed tomographic angiography in the evaluation of the venous system in potential laparoscopic renal donors

OBJECTIVE

Our objective was to assess the efficacy of single-arterial-phase, 16-slice multidetector computed tomographic (16-MDCT) angiography in the evaluation of both the renal arterial and venous systems in prospective renal donors with surgical (laparoscopic) correlation.

METHODS

Fifty-one consecutive renal donors (age range, 20-62 years; 12 men and 39 women) underwent 16-MDCT angiography followed by laparoscopic donor nephrectomy. Approval from institutional review board was obtained with waiver of consent. The arterial-phase image data set was reviewed independently by 2 abdominal radiologists for the number of renal arteries and veins, anomalies, and degree of opacification of the renal veins. Computed tomographic angiography results were compared with the surgical findings. Interobserver agreement was assessed using kappa statistics.

RESULTS

The sensitivity, specificity, and accuracy for identifying the number of renal veins in the arterial phase on 16-MDCT angiography were 96.3%, 96.07%, and 96.2% for reviewer 1 and 94.44%, 94.11%, and 94.3% for reviewer 2, respectively. Both reviewers correctly identified all venous anomalies and had substantial interobserver agreement (kappa coefficient = 0.68).

CONCLUSIONS

A single-arterial-phase image data set is sufficient for evaluation of both the renal arterial and venous anatomy in potential renal donors before laparoscopic nephrectomy. Venous-phase acquisition is not necessary, thereby substantially reducing the radiation burden on the donor.

Carotid artery wall thickness: comparison between sonography and multi-detector row CT angiography

INTRODUCTION

Prospective studies have shown that an increased thickness of the carotid wall is a significant predictor of coronary and cerebrovascular complications. Our purpose was to assess the agreement between multi-detector row computed tomography (CT) angiography (MDCTA) and colour Doppler ultrasound (CD-US) in measuring carotid artery wall thickness (CAWT) and the intima-media thickness (IMT).

METHODS

Altogether, 97 subjects (age range 64-84 years) were prospectively analysed using a four-detector row CT and a sonographic scanner. In total, 46 subjects had shown cerebral ischaemic symptoms. CAWT and IMT were measured in each patient using MDCTA and CD-US (by applying a digital calliper), respectively. Continuous data were described as the mean value +/- standard deviation and were compared using the Mann-Whitney U test. A p value <0.05 was considered significant. Bland-Altman statistics was employed to measure the agreement between MDCTA and CD-US.

RESULTS

CAWT ranged from 0.5 to 1.53 mm, with a mean value of 0.9072 mm. IMT ranged from 0.46 to 1.5 mm, with a mean value of 0.8839 mm. By analysing the Bland-Altman plot, we observed an excellent agreement between CD-US and MDCTA with a bias between methods of 0.023 +/- 0.0424 mm. A limit of agreement from -0.06 to 0.106 was recorded. Correlation coefficient r was 0.9855 (95% confidence interval 0.9808-0.989). Mann-Whitney U test indicated a p value of 0.377.

CONCLUSIONS

Obtained results indicated a significant agreement between MDCTA and CD-US in the measurement of CAWT and IMT.

CT arthrography, MR arthrography, PET, and scintigraphy in osteoarthritis

CT arthrography and MR arthrography are accurate methods for the study of surface cartilage lesions and cartilage loss. They also provide information on subchondral bone and marrow changes, and ligaments and meniscal lesions that can be associated with osteoarthritis. Nuclear medicine also offers new insights in the assessment of the disease. This article discusses the strengths and limitations of CT arthrography and MR arthrography. It also highlights nuclear medicine methods that may be relevant to the study of osteoarthritis in research and clinical practice.

Location of the transition zone in CT of small-bowel obstruction: added value of multiplanar reformations

PURPOSE

To assess the additional value of multiplanar reformations (MPR) in comparison with axial images alone for location of the transition zone in CT of mechanical small-bowel obstruction (SBO).

MATERIALS AND METHODS

Sixty-nine consecutive patients with mechanical SBO underwent 16-slice multi detector row CT (MDCT). The gold standard for the precise location of the transition zone was established by two experienced abdominal radiologists, unblinded to clinical and surgical reports, reviewing all CT examinations. On a workstation, two blinded readers independently located the transition zone using first axial slices alone and then 1 month later MPR (axial, coronal, sagittal and oblique views) according to a three-point confidence scale. Diagnostic accuracy and mean confidence score were evaluated for both the transverse and multiplanar data sets.

RESULTS

Accuracy of transition zone location for reader 1 and reader 2 was 86% and 84% with axial slices alone, and by using MPR 93% (significant: P = 0.03) and 90% (not significant: P = 0.08), respectively. Mean confidence score was significantly increased for both readers using MPR: 0.3 higher (P = 0.0001) and 0.37 higher (P = 0.0001) respectively.

CONCLUSION

MPR can increase both accuracy and confidence in the location of the transition zone in CT of SBO.

Comparison of effects of ProTaper, HeroShaper, and Gates Glidden Burs on cervical dentin thickness and root canal volume by using multislice computed tomography

The purpose of this study was to compare the effects of 3 different instruments used to prepare curved root canals on the remaining cervical dentin thickness and total amount of dentin removed from root canals during instrumentation by using multislice computed tomography. Mesiobuccal canals of 45 mandibular first molars with curvature between 30-40 degrees were divided into 3 equal groups: ProTaper, Hero Shaper, and Gates Glidden Bur with Flex-R hand file. Cervical dentin thickness and canal volume were measured before and after instrumentation by using multislice computed tomography and image analysis software. The results indicated that ProTaper removed significantly less cervical dentin from distal wall of the root (dangerous zone) than HeroShaper and Gates Glidden Bur (P < .05). The total dentin removed during canal instrumentation was significantly more with ProTaper system (P < .05).

CT of the musculoskeletal system: what is left is the days of MRI?

Magnetic resonance imaging (MRI) plays a central role in the modern imaging of musculoskeletal disorders, due to its ability to produce multiplanar images and characterise soft tissues accurately. However, computed tomography (CT) still has an important role to play, not merely as an alternative to MRI, but as being the preferred imaging investigation in some situations. This article briefly reviews the history of CT technology, the technical factors involved and a number of current applications, as well as looking at future areas where CT may be employed. The advent of ever-increasing numbers of rows of detectors has opened up more possible uses for CT technology. However, diagnostic images may be obtained from CT systems with four rows of detectors or more, and their ability to produce near isotropic voxels and therefore multiplanar reformats.

Risks associated with magnetic resonance imaging and cervical collar in comatose, blunt trauma patients with negative comprehensive cervical spine computed tomography and no apparent spinal deficit

INTRODUCTION

In blunt trauma, comatose patients (Glasgow Coma Scale score 3 to 8) with a negative comprehensive cervical spine (CS) computed tomography assessment and no apparent spinal deficit, CS clearance strategies (magnetic resonance imaging [MRI] and prolonged cervical collar use) are controversial.

METHODS

We conducted a literature review to delineate risks for coma, CS instability, prolonged cervical collar use, and CS MRI.

RESULTS

Based on our search of the literature, the numbers of functional survivor patients among those who had sustained blunt trauma were as follows: 350 per 1,000 comatose unstable patients (increased intracranial pressure [ICP], hypotension, hypoxia, or early ventilator-associated pneumonia); 150 per 1,000 comatose high-risk patients (age > 45 years or Glasgow Coma Scale score 3 to 5); and 600 per 1,000 comatose stable patients (not unstable or high risk). Risk probabilities for adverse events among unstable, high-risk, and stable patients were as follows: 2.5% for CS instability; 26.2% for increased intensive care unit complications with prolonged cervical collar use; 9.3% to 14.6% for secondary brain injury with MRI transportation; and 20.6% for aspiration during MRI scanning (supine position). Additional risk probabilities for adverse events among unstable patients were as follows: 35.8% for increased ICP with cervical collar; and 72.1% for increased ICP during MRI scan (supine position).

CONCLUSION

Blunt trauma coma functional survivor (independent living) rates are alarming. When a comprehensive CS computed tomography evaluation is negative and there is no apparent spinal deficit, CS instability is unlikely (2.5%). Secondary brain injury from the cervical collar or MRI is more probable than CS instability and jeopardizes cerebral recovery. Brain injury severity, probability of CS instability, cervical collar risk, and MRI risk assessments are essential when deciding whether CS MRI is appropriate and for determining the timing of cervical collar removal.

Multidetector-row CT angiographic imaging of the celiac trunk: anatomy and normal variants

PURPOSE

To evaluate the ability of MDCT reformations in describing the celiac trunk vascular anatomy and variations.

MATERIALS AND METHODS

A total of 555 MDCT angiographies of the abdominal aorta performed between January 2002 and July 2005 were retrospectively reviewed to assess the celiac trunk vascular anatomy and variations. All the patients with pathological condition likely to affect normal vascular anatomy as well as CT exams technically inadequate were excluded from our study.

RESULTS

A total of 524 MDCT angiographies of abdominal aorta were included in our study. The classical configuration of the celiac trunk was detected in 72.1%. The hepato-splenic trunk was detected in 50.4% of cases; the hepato-gastro-splenic trunk was detected in 19.4% of cases; the gastro-splenic trunk was detected in 2.3% of cases. The hepato-spleno-gastric trunk associated with hepatic arteries variants were found in 15.4%. The hepato-splenic trunk, the hepato-gastric trunk, the hepato-splenic-mesenteric trunk, and the spleno-gastric trunk were found in 2.7, 5, 0.4, and 3.6%, respectively. In 0.6%, we found an absent celiac trunk.

CONCLUSION

The knowledge of the type of anatomical variants and their subtypes is fundamental for a correct pre-operative vascular planning in surgical or radiological abdominal procedures. Multidetector-row CT (MDCT) provides high-quality 3D-reconstructed images and allows non-invasive assessment of normal anatomy and anatomic variants of celiac trunk.

Virtual three-dimensional computed tomography assessment of the gastric pouch following laparoscopic Roux-Y gastric bypass

BACKGROUND

The construction of the gastric pouch during surgery is largely based on the prevailing dogma of Roux-Y gastric bypass (RYGB) surgery. The scarce data that exist suggest that the smaller the gastric pouch, the greater the weight loss after surgery. Current estimations of pouch volume have inherent limitations. We describe the use of virtual three-dimensional computed tomography (3D CT) to assess pouch volume in the immediate postoperative period.

METHODS

We performed 3D CT on three patients 1 day after laparoscopic RYGB using a 16-channel multidetector CT scan. Effervescent granules were administered, along with 1 oz of water, orally to achieve gastric pouch distension. Transaxial images were transferred to the 3D workstation (Vitrea, Vital Images, Inc.) and endoluminal views of the gastric pouch were generated with perspective volume rendering. Pouch area was also measured from the standard postoperative upper gastrointestinal (UGI) contrast study.

RESULTS

All three patients were female, with a mean preoperative body mass index (BMI) of 43.7 kg/m(2) and a mean age of 44.3 years. Mean pouch height was 4.07 cm, mean pouch width was 3.79 cm, and mean pouch depth was 2.1 cm. The mean calculated pouch volume was 31.6 cm(3). The calculated pouch area using 3D CT was statistically indistinct from the pouch area calculated using the UGI study (15.2 cm(2) vs 16.9 cm(2); p = 0.549.)

CONCLUSION

For the first time, we describe the use of 3D CT to accurately measure postoperative pouch volume. In addition, we were able to confirm the utility of area (postoperative UGI) as an accurate surrogate for pouch volume.

Portosystemic shunt on CT during arterial portography: prevalence in patients with and without liver cirrhosis

BACKGROUND

To review various portosystemic shunts (PS) and to evaluate their prevalence by CT during arterial portography (CTAP) using a multidetector-row CT (MDCT).

METHODS

CTAP of 116 patients (liver cirrhosis 70 patients, non-liver cirrhosis 46 patients) was retrospectively reviewed. CTAP was performed with the catheter placed in the superior mesenteric artery using MDCT. Axial CT images of 0.625- and 3.75- or 2.5-mm thickness were obtained. Multiplanar reformation images and maximum intensity projection images were subjected to review.

RESULTS

A part of the veins in the ileocecal region drained into the right renal vein or the inferior vena cava (IVC) via the right gonadal vein in 57 patients (81%). A part of the veins of the ascending colon drained via the right renal capsular vein into the IVC in 37 patients (53%). In 46 patients without liver cirrhosis, the right gonadal and right renal capsular veins were opacified on CTAP in 22 patients (48%) and 20 patients (43%), respectively.

CONCLUSIONS

Portosystemic shunts in retroperitoneum were frequently recognized on CTAP images in patients with liver cirrhosis. The right gonadal vein and the right renal capsular vein were the most frequent routes of the portosystemic shunts. They may exist in physiological condition.

Optimizing computed tomography to reduce artifacts from titanium aneurysm clips: an in vitro study

Object

At many institutions digital subtraction angiography remains the standard imaging procedure for the postoperative evaluation of patients following placement of a cerebral aneurysm clip largely because of the artifacts produced by the clip on computed tomography (CT). The authors evaluated the effect of various imaging parameters on the quality of 3D reconstructions from CT scans while imaging a phantom to optimize the CT angiograms.

Methods

Using multidetector CT scanners with submillimeter detector collimation (0.625 mm), the authors scanned a silicone phantom with attached commercial aneurysm clips. Slice thickness, reconstruction overlap, kilovolt level, milliampere level, and pitch were varied. Neuroradiologists, who were blinded to the scanning parameters, rated the reconstructions for image quality and artifact reduction.

Results

Images of the titanium clip using 140 kV and 380 mA with 0.625-mm overlapping reconstructed slices provided excellent 3D visualization of both the clip and the aneurysm model, even when using two adjacent clips.

Conclusions

Overlapping reconstructions combined with thin-section acquisition can provide detailed images of titanium clips and surrounding tissues without the use of low-pitch values.

A new modality to evaluate the gastric remnant after Roux-en-Y gastric bypass

BACKGROUND

Gastric bypass surgery has become one of the most common operations performed in the United States. Exclusion of the gastric remnant has raised concerns about the difficulty for future evaluation of mucosal-based lesions. Current methods include retrograde endoscopy, which is technically challenging, or a surgically created gastrotomy. Both procedures are invasive. Virtual colonoscopy is becoming an accepted means of colonic mucosal evaluation. Hence, we used virtual three-dimensional computed tomograpy (3D-CT), also referred to as virtual gastroscopy, to evaluate the gastric mucosa in patients who have undergone laparoscopic Roux-en-Y gastric bypass (LRYGB).

METHODS

After institutional review board approval, 3 patients who had undergone LRYGB were consented for evaluation. Virtual gastroscopy was performed using a 16-channel multidetector CT scan, and 3D images were rendered using proprietary software (Vital Images, Inc.).

RESULTS

Endoluminal views of the gastric remnant were generated using perspective volume rendering. Virtual fly-through images were obtained by manipulating data acquired from the 3D-CT. Out of the 3 patients evaluated, we were able to achieve remnant gastric distension in 2 patients with no adverse effects.

CONCLUSION

This is the first report of performing virtual gastroscopy to evaluate the remnant stomach after LRYGB. Variations of this technique may minimize the need for invasive and technically challenging studies in this patient population.

Postnatal maturation and radiology of the growing spine

Postnatal maturation of the spine is marked by the ossification process and by changes in the shape of the vertebrae, spinal curvature, spinal canal, discs, and bone marrow. Different aspects of the spine's maturation process are demonstrated on the three most common radiologic modalities used to evaluate the spine. Conventional plain spine imaging (plain spine radiography) provides a good initial evaluation of the bony spine. CT provides better bone detail and allows finer evaluation of subtle structures, the soft tissues of the spine (discs, ligaments), and the spinal cord. MRI provides excellent resolution of the bone marrow, ligaments, and discs of the spine, and can be used as an adjunct for evaluating the soft tissue of the spine and intraspinal contents.