Multisection CT: scanning techniques and clinical applications

Four-section multidetector computed tomographic imaging of bowel obstruction: usefulness of axial and coronal plane combined reading

OBJECTIVE

To compare the diagnostic performance of axial and coronal views in multidetector-row computed tomography (MDCT) of patients with small-bowel obstruction (SBO) or large-bowel obstruction (LBO).

MATERIALS AND METHODS

Among 157 patients with clinical and radiographic findings of BO, 73 patients, who underwent MDCT and were found to have surgically proven SBO (49/73) or LBO (24/73), were retrospectively evaluated. Portal-enhanced MDCT was performed using 4 x 2.5-mm collimation; 3-mm-thick axial images were reconstructed with 2 mm of increment. Coronal views were reformatted using 3-mm-thick sections with 1 mm of increment. Three radiologists analyzed axial (session A), coronal (session B), and axial plus coronal images (session C) to identify the site, cause, and type of BO. To correlate surgical findings and MDCT results, the bowel was divided into duodenum, oral jejunum, aboral jejunum, oral ileum, aboral ileum, cecum/ascending colon, transverse colon, descending colon, and sigmoid colon/rectum. The mean diagnostic accuracy and the mean confidence score of each reader and each reading session were calculated.

RESULTS

The diagnostic accuracy of axial images was higher than that of coronal views (P = 0.014) in SBO, whereas no significant differences were found in LBO. The definition of the SBO cause was correctly assessed in 45 of 49 patients during session A, in 40 of 49 during session B, and in 45 of 49 during session C. In patients with LBO, the cause was correctly assessed in 21 of 24 patients during session A and in 22 of 24 patients during sessions B and C. All readers interpreted axial plus coronal images with a significantly higher confidence level than axial or coronal views alone, either for the detection of the site (P = 0.002) or for the identification of the cause (P < 0.001) of SBO and LBO.

CONCLUSION

The MDCT allowed accurate detection of the site and the cause of obstruction. In SBO, axial images yielded a higher diagnostic accuracy than coronal views, whereas in LBO, no differences were found between axial and coronal planes. The reading of axial plus coronal views significantly improved diagnostic confidence.

Imaging in staging of malignant lymphoma: a systematic review

Computed tomography (CT) is currently the most commonly used means for staging malignant lymphoma. 18F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET), FDG-PET/CT fusion, and whole-body magnetic resonance imaging (WB-MRI) are potential alternatives. The purpose of this study was to systematically review published data on the diagnostic performance of CT, FDG-PET, FDG-PET/CT fusion, and WB-MRI in staging of malignant lymphoma. In addition, technical aspects, procedures, advantages, and drawbacks of each imaging modality are outlined. Three CT studies, 17 FDG-PET studies, and 4 FDG-PET/CT fusion studies were included in this systematic review. The studies were of moderate methodological quality and used different scoring systems to stage malignant lymphoma. CT remains the standard imaging modality for initial staging of malignant lymphoma, while FDG-PET has an essential role in restaging after treatment. Early results suggest that FDG-PET/CT fusion outperforms both CT alone and FDG-PET alone. Data on the diagnostic performance of WB-MRI are lacking. Future well-designed studies, expressing their results according to the Ann Arbor staging system, are needed to determine which imaging modality is most accurate and cost-effective in staging malignant lymphoma.

Multidetector-row CT angiography in the study of atherosclerotic carotid arteries

Pathologies of the carotid arteries, and in particular atherosclerosis, are now an important medical problem. Stroke is the third leading cause of severe disability in the Western World leading to millions of deaths every year. Extracranial carotid atherosclerotic disease is the major risk factor for stroke. In years, with the advent of multidetector-row CT (MDCT) scanners and the use of specific angiographic protocols (MDCTA), CT imaging of the carotid arteries has become increasingly effective. In addition, the volume data obtained can be further rendered to generate high-quality two-dimensional and three-dimensional images. The purpose of this study was to review the atherosclerotic carotid arteries, their complications and how MDCTA depicts them, underlining the benefits and pitfalls of this diagnostic technique.

A Pragmatic Protocol for Reduction in the Metal Artifact and Radiation Dose in Multislice Computed Tomography of the Spine

OBJECTIVE

To assess the correlation between the metal artifact degree and the tube voltage (in peak kilovolts; kVp) and tube current (in milliamperes; mA) in multidetector row computed tomography (MDCT) and evaluate the proper protocols for reduction in the metal artifact and the radiation dose.

METHODS

We performed MDCT examinations for 13 cadavers operated for transpedicular screw insertion from C3 to C7, bilaterally. We used 80, 100, and 120 kVp in all cadavers. For the mA, we arbitrarily applied 100, 150, and 200 in 6 cadavers (experiment 1); 140, 180, and 220 in 4 (experiment 2), and randomly used mAs between 60 and 220 in 3 (experiment 3). The lengths of the artifacts emanating from the anterior and posterior tips of the screw were used for the degree of artifact.

RESULTS

In experiment 1, the mA did not significantly affect the metal artifacts (P > 0.05); but the kVp did (P < 0.05). In experiment 2, the mA and kVp did not significantly affect the metal artifact degree (P > 0.05). In experiment 3, the mA did not affect the metal artifacts, but the kVp caused changes in metal artifact degrees (simple quantitative analysis).

CONCLUSIONS

The proper parameters for the simultaneous reduction in the artifact and radiation dose are suggested to be tube voltages from 100 to 120 kVp and tube currents lower than the generally used values of 200 to 220 mA.

Imaging in local staging of gastric cancer: a systematic review

PURPOSE

Endoscopic ultrasound (EUS) has been established as the diagnostic modality of choice in local (T) staging of gastric cancer. Multidetector row computed tomography (MDCT) and magnetic resonance imaging (MRI) are promising alternatives. The aim of this study was to systematically review the literature regarding the performance of each of these imaging modalities.

METHODS

A systematic search for relevant studies was performed in the PubMed/MEDLINE and EMBASE databases. Two reviewers independently assessed the methodological quality of each study. Local staging performance of included studies was calculated.

RESULTS

Twenty-two EUS studies, five MDCT studies, one combined EUS and MDCT study, and three MRI studies met the inclusion criteria. The studies were of moderate methodological quality. Diagnostic accuracy of overall T staging for EUS, MDCT, and MRI varied between 65% to 92.1%, 77.1% to 88.9%, and 71.4% to 82.6%, respectively. Sensitivity for assessing serosal involvement for EUS, MDCT, and MRI varied between 77.8% to 100%, 82.8% to 100%, and 89.5% to 93.1%, respectively. Specificity for assessing serosal involvement for EUS, MDCT, and MRI varied between 67.9% to 100%, 80% to 96.8%, and 91.4% to 100%, respectively.

CONCLUSION

EUS, MDCT, and MRI achieve similar results in terms of diagnostic accuracy in T staging and in assessing serosal involvement. Most experience has been gained with EUS. Few MDCT studies and even fewer MRI studies are available. Thus, EUS remains the first-choice imaging modality in preoperative T staging of gastric cancer.

Hereditary hemorrhagic telangiectasia: clinical features in ENG and ALK1 mutation carriers

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by epistaxis, mucocutaneous telangiectases and visceral arteriovenous malformations (AVMs), particularly in the brain (CAVMs), lungs (PAVMs), liver (HAVMs) and gastrointestinal tract (GI). The identification of a mutated ENG (HHT1) or ALK-1 (HHT2) gene now enables a genotype-phenotype correlation.

OBJECTIVE

To determine the incidence of visceral localizations and evaluate phenotypic differences between ENG and ALK1 mutation carriers.

METHODS

A total of 135 consecutive adult patients were subjected to mutational screening in ENG and ALK1 genes and instrumental tests to detect AVMs, such as chest-abdomen multislice computed tomography (MDCT), brain magnetic resonance imaging and magnetic resonance angiography (MRI/MRA), upper endoscopy, were offered to all patients, independent of presence of clinical symptoms. The 122 patients with identified mutations were enrolled in the study and genotype-phenotype correlations were established.

RESULTS

PAVMs and CAVMs were significantly more frequent in HHT1 (75% vs. 44%, P < 0.0005; 20% vs. 0%, P < 0.002, respectively) and HAVMs in HHT2 (60% vs. 84%, P < 0.01). No age difference was found for PAVMs whereas HAVMs were significantly higher in older patients in both HHT1 and HHT2. Neurological manifestations secondary to CAVMs/PAVMs were found only in HHT1 patients, whereas severe liver involvement was detected only in HHT2. Respiratory symptoms were mainly detected in HHT1.

CONCLUSIONS

Our study evidences a higher visceral involvement in HHT1 and HHT2 compared with previous reports. HHT1 is more frequently associated with congenital AVM malformations, such as CAVMs and PAVMs whereas HHT2 predominantly involves the liver. The ENG gene should be first targeted for mutational screening in the presence of large PAVM in patients < 45 years.

Diagnosis and management of blunt pancreatic ductal injury in the era of high-resolution computed axial tomography

BACKGROUND

Blunt pancreatic ductal injury is an uncommon but potentially morbid injury that can be difficult to diagnose and manage. Computed axial tomography (CAT) scan has historically been unreliable for the detection of ductal injury, but the advent of high-resolution CAT should improve diagnostic accuracy.

METHODS

From our prospectively maintained trauma registry, consecutive patients who had a diagnosis of blunt pancreatic injury with or without a subsequent laparotomy during the time period from January 1995 through December 2004 were retrospectively reviewed. Pancreatic ductal injury was treated exclusively with distal pancreatic resection (DPR) without adjunctive endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography.

RESULTS

Of 50 patients with blunt pancreatic injury, 33 patients had both preoperative CAT scan and laparotomy. Although the CAT scan interpretation and operative findings corresponded precisely for all pancreatic injuries in only 55% of cases, CAT scan was 91% sensitive and 91% specific for identifying pancreatic ductal injury. Eleven patients with confirmed pancreatic ductal injury underwent DPR. There were no postoperative pancreas-related deaths and only 1 pancreas-related complication among survivors, a patient with a low-output pancreatic fistula that resolved after 5 weeks.

CONCLUSIONS

Blunt pancreatic ductal injury may be accurately diagnosed with preoperative CAT scan, without adjunctive endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography, and is effectively and safely treated with DPR.

MDCT diagnosis of appendicitis using only coronal reformations

The purpose of this study was to assess the feasibility of diagnosing appendicitis based on coronal reformations without the aid of transverse images. Abdominal and pelvic computed tomography (CT) scans of 53 patients (27 with appendicitis and 26 without appendicitis) were reviewed. All scans were obtained using a four-slice multi-detector row CT. The radiologists were not aware of the final diagnosis. Cases were reviewed for the visualization of the appendix and presence of appendicitis. All images were reviewed on picture archiving and communication systems. There were no false positives for diagnosing appendicitis when using either the transverse or coronal reformations. Appendicitis was not seen on the coronal images in one case, and there were no false negatives when transverse reformations alone were used. This difference was not statistically significant (p < 0.0001 for both modes of display). The sensitivity for diagnosing appendicitis based on the coronal images alone was 96%, the specificity was 100%, and the accuracy was 98%. Coronal reformations decreased the number of images reviewed by 19%. CT diagnosis of appendicitis based on the coronal images is accurate.

Disorders of acetabular labrum and articular cartilage in hip dysplasia: evaluation using isotropic high-resolutional CT arthrography with sequential radial reformation

OBJECTIVE

Acetabular labral tear may predispose to adjacent articular cartilage disorder and hip osteoarthritis in patients with hip dysplasia. We evaluated the diagnostic ability of isotropic computed tomography (CT) arthrography with radial reformation technique for detection of acetabular labral and articular cartilage disorders, and evaluate those interactions in hip dysplasia.

METHODS

Forty-one hips in 29 patients with hip dysplasia received CT arthrography with isotropic spatial resolution of 0.5mm. After processing of multiplanar radial reformation over the whole acetabular circumference, frequencies of labral tear and acetabular cartilage disorder were evaluated at six divided zones of the weight-bearing areas. Of the 41 hips, 20 hips underwent arthroscopic examinations, and sensitivity, specificity and accuracy for detecting labral tear and acetabular cartilage disorder by CT arthrography were calculated using the arthroscopic findings as the standard of reference.

RESULTS

The sensitivity, specificity and accuracy of CT arthrography were 97%/87%/92% for labral tear and 88%/82%/85% for acetabular cartilage disorder, respectively, using arthroscopic findings as the reference. The CT arthrography showed significantly higher frequency of labral and acetabular cartilage disorders at the anterior zones. Those zones with labral tear had significantly higher frequency of adjacent cartilage disorder than zones without labral tear.

CONCLUSIONS

Isotropic CT arthrography with radial reformation technique allowed simultaneous, accurate assessment of labral and cartilage disorders in the whole acetabular circumference. Our findings indicated that labral tear is closely associated with adjacent cartilage disorder in hip dysplasia.

Multi-detector computed tomography demonstrates smoke inhalation injury at early stage

A multitrauma victim was transported to our trauma centre. Smoke inhalation injury was suspected based on trauma history and clinical examination. The first trauma computer tomography (CT) obtained 2.8 h after the injury revealed subtle ground-glass opacifications with mainly peribronchial distribution and patchy peribronchial consolidations centrally in the left lung. A repeated scan showed a more distinctive demarcation of the peribronchial opacities, further substantiating the clinically verified smoke inhalation injury. The golden standard for diagnosing smoke inhalation injury still is fibroptic bronchoscopy examination. This paper shows that lesions typical to smoke inhalation injury appear much earlier than previously reported. Whether assessment of smoke inhalation injury severity using CT could clinically benefit patients is controversial and still requires further research. Multi-detector computed tomography is readily available in trauma centres and to simply neglect its potential as a diagnostic tool in some inhalation injury would be unwise.

Preoperative RFA simulation for liver cancer using a CT virtual ultrasound system

We developed a computed tomography (CT) virtual ultrasound system (CVUS) as an imaging system to support treatment under percutaneous ultrasound (US) guidance. This prototype clinical system, produced in collaboration with Tokyo Medical University, uses display software developed by Toshiba Medical Systems. We examined the utility of this system by scheduling treatment plans preoperatively and simulating puncture and radiofrequency ablation (RFA) for liver cancer. The study enrolled 51 liver cancer patients with 66 nodules 0.8-8cm in diameter in which RFA was performed between June 2004 and December 2004. Virtual US and multiplanar reconstruction (MPR) images were constructed on the basis of DICOM CT data and puncture and ablation of liver cancer were simulated. The following were evaluated: (1) how to avoid complications and determine an appropriate puncture route by simulating puncture with C-mode MPR images; (2) determination of the three-dimensional location of the tumor for ablation, as well as the adjacent organs and vessels, by MPR rotation 360 degrees around the center of the tumor (center lock); and (3) how to determine the center and volume of ablation and avoid injuries to nearby organs and vessels by simulating ablation procedures. C -mode MPR images were effective for (1) determining and modifying the puncture route in 35 of 51 cases (69.6%) and (2) determining the spatial location of vessels and nearby organs in 50 of 51 cases (98.0%) by the center lock; and (3) simulating the ablation helped determine the center and volume of ablation by avoiding injuries to vessels and nearby organs in 45 or 51 cases (88.2%). Taken together, the CVUS allowed easy simulation of local treatment of liver cancer under US guidance using CT data alone and the preoperative simulation predicted an improvement in the safety of local therapy of liver cancer.

Trends in oncological CT imaging: clinical application of multidetector-row CT and 3D-CT imaging

Computed tomography (CT) plays an essential role in oncological imaging as the modality of screening for malignancies, mapping out the treatment strategy at staging, assessing response to the treatment, and following up patient outcome after the treatment. The advent of multidetector-row CT (MDCT) has brought about dramatic changes in clinical oncological imaging. The very superior temporal and spatial resolution of MDCT has transformed CT imaging from a transaxial cross-sectional technique into an isotropic volume-imaging technique. MDCT facilitates multiphasic contrast-enhanced study for a wide range of body scanning in a single examination, as well as providing flexibility of multidirectional reconstruction and high-quality three-dimensional imaging. With increases in the number of detector rows year by year, systems with 64-detector rows have become commercially available in 2006. The purpose of this article is to review the status of CT imaging in oncological imaging: (1) to outline the impact of MDCT, focusing on oncological imaging and (2) to review the clinical applications of oncological CT imaging with MDCT.

Diagnostic value of micro-CT in comparison with histology in the qualitative assessment of historical human skull bone pathologies

Cases of pathologically changed bone might constitute a diagnostic pitfall and frequently need histological methods to be etiologically properly evaluated. With micro-computed tomography (microCT), a new epoch of 2D and 3D imaging has been launched. We evaluated the diagnostic investigation of this analytical method versus well established histological investigations of historical human bone. Pathological changes due to various etiologies (infectious, traumatic, endocrinological, neoplasia) observed in autopsy-based macerated human skulls (Galler Collection, Natural History Museum Basel, Switzerland) were investigated by microCT and compared with histological thin ground sections using polarized light. Micro-CT images visualize the architecture of the bone with high spatial resolution without preparation or destruction of the sample in the area to be sectioned. Changes in the bone surfaces as well as alterations of the diploë can be assessed. However, morphological patterns caused by reactive response, such as typical arrangements of collagen fibers, can only be visualized by the microscopic investigation of thin ground sections using polarized light. A great advantage of microCT is the high number of slices obtained so that spatial differences within the areas of the specimen become visible. Micro-CT is a valuable tool for the diagnosis of vestiges of skull bone diseases. Its advantages over histology are the fast, automated image acquisition and the fact that the specimen is not completely destroyed. Only excision of the area to be scanned is necessary, if the specimen is too large to be scanned as a whole. Further, the 3D visualization of the micro-architecture allows an easy orientation within the sample, for example, for the choice of the location of the histological slices. However, the need to differentiate woven from lamellar bone still makes histology an indispensable method.

CT Cystography with Multiplanar Reformation for Suspected Bladder Rupture: Experience in 234 Cases

OBJECTIVE

CT cystography has replaced conventional cystography in the evaluation of patients with suspected bladder rupture in most trauma centers. We performed this retrospective review to determine the accuracy of CT cystography and the role of multiplanar reformation in the diagnosis of bladder injury.

MATERIALS AND METHODS

The patient cohort was composed of trauma patients with clinically or CT-suspected bladder ruptures who were evaluated with CT cystography using two different MDCT scanners at our level 1 trauma center. The patients were identified through Folio, a radiology research tool software system. The CT cystography results were compared with the findings at surgery, clinical follow-up, or both.

RESULTS

Between January 1, 2000, and December 31, 2004, 234 patients were examined in our level 1 trauma center with CT cystography. From the total of 234 examinations, 216 (92.3%) were interpreted as negative and 18 examinations (7.7%) were interpreted as positive. On the 18 positive examinations, 11 were extraperitoneal bladder rupture, five were intraperitoneal bladder rupture, and two were combined intraperitoneal and extraperitoneal bladder rupture. Surgical bladder exploration and repair were performed in nine of the 18 cases. Seven (77.8%) of the nine cases had operative findings consistent with the CT cystogram findings. The overall sensitivity and specificity of CT cystography in diagnosing bladder rupture were each 100%. For extraperitoneal bladder rupture, the sensitivity and specificity were 92.8% and 100%, respectively. For intraperitoneal rupture, the sensitivity and specificity were 100% and 99%, respectively.

CONCLUSION

CT cystography is accurate for diagnosing bladder rupture. Sagittal and coronal multiplanar reformations may be helpful in identifying most sites of bladder rupture.

Increased Radiodensity of the Proximal Pole of the Scaphoid

OBJECTIVES

To determine whether the proximal pole (PP) of the scaphoid is denser than the distal pole (DP) in a diverse population of patients undergoing computed tomography (CT) imaging of the wrist.

METHODS

Sixty-nine patients who had CT of the wrist were retrospective reviewed. We measured CT density of the medullary bone of PP and DP of the scaphoid and calculated PP/DP ratio. To evaluate the variability of PP/DP ratio, we compared the ratios of these 3 groups. These patients were separated into 3 groups based on their diagnoses: group 1, healed scaphoids treated by casting; group 2, scaphoid nonunions; group 3, intact scaphoids.

RESULTS

Proximal pole was denser than DP in most subjects. Proximal pole/distal pole ratio was similar among groups (P < 0.05). Fracture healing, sex, and age did not affect this ratio. However, we did not study scaphoids with avascular necrosis.

CONCLUSIONS

Proximal pole was denser than DP in most of our subjects, including those with intact scaphoids, healing scaphoid fractures, and nonunions.

Multidetector-row computed tomography diagnosis of small bowel obstruction: can coronal reformations replace axial images?

Feasibility of diagnosing small bowel obstruction on multidetector-row computed tomography (MDCT) using coronal reformations alone is evaluated. Three radiologists with subspecialty training in abdominal imaging reviewed abdominopelvic CT of 67 patients in consensus. Thirty-four patients had surgically proven small bowel obstruction. The remaining 33 patients had CT for other reasons and had no intestinal obstruction. The images were displayed in either axial or coronal planes and were reviewed on separate days . Each CT was evaluated for the presence of small bowel obstruction and its etiology when applicable. Thirty-three (100%) of 33 patients were correctly diagnosed not to have intestinal obstruction on coronal images. Thirty-four (100%) of 34 patients were correctly diagnosed to have small bowel obstruction on both forms of image display. There were five patients where the final surgical diagnosis for the etiology of small bowel obstruction did not agree with the interpretation of either the coronal or axial images; however, in all five patients, the interpretations of axial and coronal images were similar. In only one patient, the etiology of small bowel obstruction based on the coronal images did not agree with that of axial images and the surgical result; however, the site of small bowel obstruction was correctly diagnosed. There were approximately 20% fewer images in the coronal reformation data set, and the radiologists found review of these images to be easier for localizing the zone of transition in small bowel obstruction. Very high diagnostic accuracy can be achieved based on coronal reformations alone, and this form of image display may potentially be substituted for the conventional axial images. Since there are fewer images to review when the studies are displayed in coronal plane, this may positively impact radiologist workflow.

Impact of the introduction of 16-row MDCT on image quality and patient dose: phantom study and multi-centre survey

The purpose was to compare the image quality and patient dose between 4- and 16-row MDCT units and to evaluate the dispersion of the dose delivered for common clinical examinations. Four 4- and 16-row MDCT units were used in the study. Image noise levels from images of a CatPhan phantom were compared for all units using a given CTDI(vol) of 15.0+/-1.0 mGy. Standard acquisition protocols from ten centres, shifted from 4- to 16-row MDCT (plus one additional centre for 16-row MDCT), were compared for cerebral angiography and standard chest and abdomen examinations. In addition, the protocols used with 16-row MDCT units for diagnosis of the unstable shoulder and for cardiac examinations were also compared. The introduction of 16-MSCT units did not reduce the performance of the detectors. Concerning the acquisition protocols, a wide range in practice was observed for standard examinations; DLP varied from 800 to 5,120 mGy x cm, 130 to 860 mGy x cm, 410 to 1,790 mGy x cm and 850 to 2,500 mGy x cm for cerebral angiography, standard chest, standard abdomen and heart examinations, respectively. The introduction of 16-row MDCT did not, on average, increase the patient dose for standard chest and abdominal examinations. However, a significant dose increase has been observed for cerebral angiography. There is a wide dispersion in the doses delivered, especially for cardiac imaging.

MDCT in the evaluation of skeletal trauma: principles, protocols, and clinical applications

Multidetector computed tomography (MDCT) scanners have made volume imaging possible and are used extensively to study polytrauma patients, especially in the evaluation of the spine and peripheral skeleton. An MDCT scanner coupled with a modern workstation has become an essential diagnostic tool for any emergency department. Familiarity with the basic physical principles of MDCT such as projection data, section collimation, and beam collimation is important to achieve high-quality imaging while keeping unnecessary radiation to a minimum. After a polytrauma MDCT examination, images can be reconstructed to obtain different slice thickness, slice interval, fields of view, or reconstruction kernels. No additional scanning is needed for imaging the thoracolumbar spine or bony pelvis. High-quality multiplanar reformation (MPR) and three-dimensional (3-D) images can be created at the workstation using the volumetric data. However, MDCT is a high-dose examination, and care should be taken to use as low a dose as possible. In the musculoskeletal system, MDCT has long been used for evaluation of spinal and pelvic trauma; however, the frequency of its use in extremity trauma has been low. In the extremities, radiography seems to underestimate the extent and severity of injury, especially in complex areas such as the shoulder, elbow, wrist, knee, and ankle. MDCT in the extremities is helpful in fracture detection, evaluation, characterization, and treatment planning. The MPR images give excellent structural detail, and the 3-D images help in understanding the spatial relations, which is important for fracture classification and for preoperative planning. MDCT is also helpful in the follow-up of postoperative results, even in the presence of hardware. Tendon injuries can also be evaluated with MDCT.

Coronal reformations of the chest on 64-row multi-detector row CT: Evaluation of image quality in comparison with 16-, 8- and 4-row multi-detector row CT

PURPOSE

To evaluate image quality of coronal reformations of chest performed on 64-row MDCT in comparison with 16-, 8- and 4-row MDCT.

MATERIALS AND METHODS

Consecutive patients who underwent pulmonary CT angiography using four different MDCT scanners were retrospectively studied with IRB approval: (1) n=30, 64-row MDCT; (2) n=30, 16-row MDCT; (3) n=30, 8-row MDCT; (4) n=30, 4-row MDCT. Coronal reformatted images (2 mm thickness and 2mm intervals for 64-row MDCT; 5 mm thickness and 5 mm intervals for 16-, 8- and 4-row MDCT) were evaluated by consensus reading of two board-certified radiologists who were blinded to scanner type. The image quality of overall chest appearance and individual thoracic structures including heart, aorta and pulmonary arteries was graded using five-point scale. Grades from four different scanners were compared using Kruskal-Wallis test. A second evaluation was performed in 48 randomly selected patients (12 patients for each scanner). Reproducibility was assessed using weighted-kappa analysis.

RESULT

Significant reproducibility was observed between the first and second evaluations in 48 patients both for image quality of overall chest (weighted kappa=0.826) and each thoracic structure (mean weighted kappa=0.803; range, 0.729-0.858). Image quality of overall chest and individual thoracic structures differed significantly among four different MDCT groups, with 64-row MDCT having the highest grades, followed by 16-, 8- and 4-row MDCT (mean grades for overall chest in each scanner: 3.9, 3.0, 2.4 and 1.9, respectively) (P<0.0001 for overall chest and each thoracic structure).

CONCLUSION

When comparing coronal reformations of chest using four different MDCT scanners, the 64-row MDCT had the highest image quality for overall chest appearance and individual thoracic structures, followed by 16-, 8- and finally 4-row MDCT.

Maximizing clinical information obtained by CT

CT scanning is an integral part of the urologist's practice today. It is the most commonly used imaging modality and the one with which urologists are most familiar. CT urography, CT angiography, and 3D reconstruction enable the urologist to perform comprehensive evaluations of patients who have different urologic diseases, using a single imaging modality. It is thus prudent that urologists become familiar with CT applications, to maximize the clinical information available from them.

Three-dimensional visualization of the nasal cavity and paranasal sinuses. Clinical results of a standardized approach using multislice helical computed tomography

OBJECTIVE

The aim of this study was to introduce 3-dimensional (3D) visualization of the nasal cavity and paranasal sinuses as a diagnostic tool and to examination the clinical results of its standardized application.

METHODS

One hundred sixty patients with chronic or acute nasal symptoms underwent helical computed tomography scanning and fiberoptic endoscopy of the sinuses, and 120 of them underwent endoscopic sinus surgery. The 3D images were compared with the axial and multiplanar reconstructed images using a checklist comprising important anatomic landmarks. After qualitative assessment of the representation of anatomic structures in healthy subjects, the method was applied to pathologic cases. The 3D images of these patients were correlated with the preoperative and intraoperative findings.

RESULTS

Six hundred virtual endoscopies (VEs) were performed. The VE views allowed a realistic illustration of the various pathologic findings, except from cases with highly obstructive sinonasal disease. The correlation between the preoperative fiberoptic endoscopy and the intraoperative findings was significant (r = 0.83, P = 0.001).

CONCLUSION

The standardized clinical application of this method serves as an important supplement to 2-dimensional slices and conventional endoscopy.

Evaluation of Living Renal Donors: Accuracy of Three-dimensional 16-Section CT

PURPOSE

To retrospectively assess the sensitivity and specificity of three-dimensional (3D) 16-section computed tomography (CT) in the evaluation of vessels, pelvicalyceal system, and ureters in living renal donors, with surgical findings as the reference standard.

MATERIALS AND METHODS

This was a HIPAA-compliant study. Institutional review board approval was obtained for the review of subjects' medical records and data analysis, with waiver of informed consent. Forty-six renal donors (18 men, 28 women; mean age, 42 years) were examined with 16-section CT. Two blinded reviewers independently studied renal vascular and urographic anatomy of each donor CT scans by fist using 3D images alone, then transverse images alone, and finally transverse and 3D data set. Image quality, degree of diagnostic confidence, and time used for review were recorded. Sensitivity and specificity were calculated.

RESULTS

For 3D images, transverse images, and transverse in conjunction with 3D data sets, the respective sensitivity and specificity of CT in evaluation of accessory arteries by reviewer 1 were 100% and 100%, 89% and 100%, and 100% and 100%, and those by reviewer 2 were 89% and 97%, 89% and 100%, and 89% and 100%; the respective sensitivity and specificity in evaluation of venous anomalies by reviewer 1 were 100% and 98%, 100% and 98%, and 100% and 98%, and those by reviewer 2 were 100% and 98%, 100% and 95%, and 100% and 98%. For focused comprehensive assessment of renal donors with 3D scans alone, a reviewer on average (average of reviewers 1 and 2) used 2.4 minutes per scan, demonstrated full confidence in 93%, and rated the quality as excellent in 76%.

CONCLUSION

For focused assessment of renal vascular and urographic anatomy, review of 3D data set alone provides high sensitivity and specificity with regard to findings seen at surgery.

Evaluation of thoracic abnormalities on 64-row multi-detector row CT: Comparison between axial images versus coronal reformations

PURPOSE

To evaluate the capability of coronal reformations of chest on 64-row MDCT in demonstrating thoracic abnormalities in comparison with axial images.

MATERIALS AND METHODS

Thirty-eight consecutive patients who underwent pulmonary CTA on 64-row MDCT were retrospectively studied with institutional review board (IRB) approval. Contiguous 2 mm axial and coronal images were reviewed independently with a 1-week interval, by consensus reading of two board-certified radiologists. Overall image quality was graded using a five-point scale. Abnormalities in mediastinum, hilum, pulmonary vessels, aorta, heart, esophagus, pleura, chest wall, and lung parenchyma were scored: 1 = definitely absent, 2 = probably absent, 3 = equivocal, 4 = probably present, 5 = definitely present. Scores on axial and coronal images were compared using weighted kappa analysis.

RESULTS

Overall image quality was not different with statistical relevance between axial and coronal images (mean/median scores; 3.7/4; 3.6/4, respectively, P = 0.286, Wilcoxon signed-rank test). Significant agreement was observed between axial and coronal scores (mean weighted kappa, 0.661; range, 0.362-1). Agreement was almost perfect for pneumothorax, lung and pleural mass, effusion and consolidation (weighted kappa=0.833-1); substantial for pulmonary embolism, trachea, mediastinal lymphadenopathy and non-skeletal chest wall lesion, heart, esophagus, and emphysema (weighted kappa, 0.618-0.799); moderate for atelectasis, mediastinum, hilar nodes, aorta, other lung lesions, skeletal chest wall lesions, linear scarring, nodules > 1 cm, pulmonary artery abnormalities and pleural thickening (weighted kappa, 0.405-0.592); and fair for nodules < 1 cm (weighted kappa = 0.362).

CONCLUSION

Coronal reformations on 64-row MDCT had substantial agreement with axial images for evaluation of the majority of thoracic abnormalities.

CT Histogram Analysis in Pathologically Proven Adrenal Masses

OBJECTIVE

The purpose of this article is to evaluate a histogram analysis method for distinguishing adrenal adenomas from metastases, pheochromocytomas, and adrenocortical carcinomas on CT.

MATERIALS AND METHODS

A pathology database was searched, and 335 adrenalectomies from 1995 to 2002 were identified. CT images were available for retrospective review in 187 patients (93 males, 94 females; age range, 15-84 years; mean age, 55.2 years) with 208 adrenal masses. This included 112 adenomas in 104 patients, 48 metastases in 39 patients, 40 pheochromocytomas in 36 patients, and eight adrenocortical carcinomas in eight patients. Histogram analysis was performed using a circular region of interest for mean attenuation, number of pixels, number of negative pixels (< 0 H), and percentage of negative pixels by two interpreters. Areas of necrosis were excluded from measurements. Observer agreement was calculated.

RESULTS

In 72 of 76 (94.7%) and 63 of 72 (87.5%) adenomas, respectively, interpreters found attenuation values greater than 10 H contained negative pixels on unenhanced CT scans. None of the enhanced adenomas had mean attenuation less than or equal to 10 H, but 24 (38.7%) and 28 (45.2%), respectively, had negative pixels. Negative pixels were present in unenhanced and enhanced metastases, pheochromocytomas, and carcinomas. Using a 5% or 10% negative pixel threshold value to diagnose adenoma improved specificity but diminished sensitivity. Specificity for a 10% negative pixel threshold was approximately 88% for unenhanced CT scans and 99% for enhanced CT scans, with sensitivities of 71% and 12%, respectively.

CONCLUSION

Although specificity for the diagnosis of adenomas on enhanced CT scans with histogram analysis was high when a 10% negative pixel threshold was used, low sensitivity likely limits clinical usefulness.

Quantitative analysis for computed tomography findings of various diffuse lung diseases using volume histogram analysis

OBJECTIVES

: The aim of this study was to achieve the quantitative analysis of the characteristic computed tomography (CT) findings and course of interstitial pneumonia using the volume histogram method.

METHODS

: Contrast (CNT), variance (VAR), and entropy (EPY) values from whole-lung volume data were compared between normal lungs and 5 diseases that have characteristic CT findings. Thirteen cases with nonspecific interstitial pneumonia (NSIP) were evaluated before and after treatment.

RESULTS

: In cases with thickening of the bronchovascular bundles and interlobular thickening, ground-glass attenuation, airspace consolidation, and honeycombing, the values of VAR and EPY were greater than those in the normal cases (P < 0.05). In the cases with NSIP, the CNT value after treatment was significantly greater and the values of VAR and EPY after treatment were significantly lower than those before treatment (P < 0.05).

CONCLUSIONS

: Volume histogram analysis is a promising method for the evaluation of diffuse lung diseases and the effectiveness of treatment.

[Multislice computed tomographic myelography]

While magnetic resonance imaging (MRI) is the first line modality in depicting intramedullary spinal lesions, computed tomographic (CT) myelography has gained renewed attention due to the introduction of multislice scanning (MS-CT). Compared with conventional CT, MS-CT permits rapid, high-resolution imaging of various spinal pathologies with extended scan length. Although soft tissue contrast is inferior to that with MRI, MS-CT myelography performs best in detailed assessment of osseous pathologies, 3D imaging of orthopedic and anesthesiologic implants, and showing dural leakage and causes of CSF circulation impairment. Whenever MRI is not available or contraindicated, MS-CT myelography is the method of choice for evaluating spinal lesions.

The utility of head computed tomography in the emergency department evaluation of syncope

OBJECTIVE

Current guidelines for evaluation of syncope recommend that in the absence of objective focal neurologic findings, head computed tomography (HCT) may not be necessary. Compliance with this recommendation is highly variable, which may be due in part to the lack of currently available evidence. We undertook the following investigation to determine whether HCT aids in the diagnostic investigation of syncope.

METHODS

This study was a retrospective chart review of all adult patients who presented to an urban emergency department, and who had a HCT ordered for syncope, during a 6-month period in 2001. Patients with competing indications for HCT, or those with a presentation consistent with seizures were excluded. Charts were assigned to the "positive" or "negative" HCT group depending on whether the treating physician considered HCT findings relevant to the syncopal event.

RESULTS

A total of 202 patients had a HCT performed for syncope. Eighty-five patients met one or more of the exclusion criteria. HCT of the remaining 117 patients were analyzed. None of the 117 patients had a HCT finding that was clinically related to the syncopal event.

CONCLUSIONS

HCT yielded no relevant clinical findings in our entire sample of patients with syncope. Our findings combined with previous studies add to the growing body of evidence that HCT for syncope in the absence of focal neurologic findings may not be necessary.

Optimization of Multiplanar Reformations from Isotropic Data Sets Acquired with 16–Detector Row Helical CT Scanner

Institutional review board approval and waiver of consent were obtained for the patient component of this retrospective HIPAA-compliant study. By using an anthropomorphic phantom and metal oxide semiconductor field effect transistor detectors, radiation dose was determined for one eight-detector row and two 16-detector row computed tomographic (CT) protocols. A custom phantom was scanned by using the three protocols to identify isotropy. Contrast-to-noise ratios (CNRs) were determined for the same protocols by using a third phantom. Seven patients had undergone isotropic 16-detector row CT of the abdomen and pelvis. Anonymized coronal reformations at various thicknesses were ranked qualitatively by three radiologists. Effective dose equivalents were similar for the eight- and 16-detector row protocols. When transverse and coronal reformations of data acquired in the custom phantom were compared, coronal reformations obtained with the 16-detector row and 0.625-mm section thickness protocol were found to be nearly identical to the transverse image for all sets of line pairs. CNRs were consistently highest on 5-mm-thick coronal reformations (CNR range, 1.2-3.3). For qualitative assessment, 2- and 3-mm-thick coronal reformations were consistently preferred.

The incidence and distribution of burst fractures

This study was conducted to assess occurrence and distribution of burst fractures as well as common accident mechanisms and the associated neurologic deficit. Using picture archiving and communications system, all emergency multidetector computed tomography studies over 34 months were retrieved and evaluated for burst fractures by two radiologists by consensus. Initial neurological findings were retrieved from patients' medical records. One hundred fifty-two patients (112 male) with a total of 169 burst fractures were found. In both genders, the incidence of burst fractures peaked at the thoracolumbar junction and between levels T5 and T8. In 10% of cases, more than one burst fracture was seen, thereof 53% on noncontiguous levels. Main accident mechanisms were falls, traffic, and sports. Neurological deficit was highest in patients with burst fractures of the cervical spine, independent of accident mechanism, and lowest in thoracolumbar junction fractures. Burst fractures occur frequently in high energy traumas and are most commonly associated with falling and traffic accidents. Multiple burst fractures occur in 10% of cases, half thereof on noncontiguous levels.

Multidetector CT of the central airways

Multidetector CT (MDCT) has revolutionized non-invasive imaging of the central airways. Compared to single-detector helical CT scans, MDCT results in higher spatial resolution, faster speed, greater anatomic coverage, and higher quality multiplanar reformation and 3-D reconstruction images. This article reviews recent advances in central airway imaging with MDCT. A special emphasis is placed upon the role of advanced reconstruction methods and functional imaging.

Principles of tumor imaging

Tumors involving the upper extremity are not uncommon. Although there is a wide variety of lesions that may occur in the hand and wrist, there are certain lesions which have a predilection for this location. This chapter will highlight the spectrum of imaging modalities available for the evaluation of upper extremity tumors, providing imaging guidelines for optimum selection of radiological examinations. It presents an overview of imaging of the hand and wrist, emphasizing the fundamental principles inherent to tumor imaging. Modalities reviewed include nuclear scintigraphy, positron emission tomography, sonography, computed tomography, arteriography, magnetic resonance imaging, and magnetic resonance angiography.

Small-bowel obstruction: coronal reformations from isotropic voxels at 16-section multi-detector row CT

PURPOSE

To retrospectively assess the added value of coronal reformations of the abdomen and pelvis from isotropic voxels by using 16-section multi-detector row computed tomography (CT) for the diagnosis of small-bowel obstruction (SBO).

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the institutional review board of this medical center with a waiver of informed consent. One hundred consecutive patients (40 men and 60 women; mean age, 55 years) suspected of having SBO and abdominal pain underwent 16-section multi-detector row CT with coronal reformations. Twenty-nine patients had a final diagnosis of SBO, and 71 patients did not. Three independent readers blinded to the diagnosis interpreted the CT scout scan, then transverse scans alone, and then transverse plus coronal scans for the presence of SBO and abnormal wall enhancement. Confidence was scored with a 1-5 scale (1 = absent, 5 = present).

RESULTS

Mean sensitivity and specificity of CT scout alone, transverse CT alone, and transverse plus coronal CT for the diagnosis of SBO were 88% and 86%, 87% and 87%, and 87% and 90%, respectively (not significant). In patients without SBO, transverse plus coronal CT enhanced confidence in the exclusion of SBO (P = .01). In patients with SBO, transverse plus coronal CT enhanced confidence in the diagnosis of SBO and identification of abnormal wall enhancement (P = .01).

CONCLUSION

Transverse 16-section multi-detector row CT data sets are an excellent test for the diagnosis of SBO, while the addition of coronal reformations obtained from these isotropic data sets adds confidence to the diagnosis and exclusion of SBO.

Orthopedic Hardware Complications Diagnosed with Multi–Detector Row CT

PURPOSE

To retrospectively evaluate multi-detector row computed tomography (CT) for the depiction of orthopedic hardware complications in the spine and appendicular skeleton.

MATERIALS AND METHODS

This HIPAA-compliant study had institutional review board approval; patient informed consent was not required. Results of 114 multi-detector row CT studies performed because of possible hardware complications in 109 patients (57 men, 52 women; mean age, 44 years; age range, 12-82 years) were available for analysis. The CT studies were retrospectively reviewed and compared with clinical or surgical outcomes, which were used as the reference standard. In another experiment, detection of hardware complications on radiographs and multi-detector row CT images was compared between two readers for selected cases (18 positive and 26 negative) by using receiver operating characteristic (ROC) methods.

RESULTS

For 91 (80%) of 114 multi-detector row CT studies, the complication status could be determined on the basis of clinical or surgical outcomes. Twenty-three multi-detector row CT studies were confirmed to be positive (revealing 10 cases of nonunion, five cases of hardware malplacement, three cases of hardware loosening, three perihardware fractures, and two chronic infections), and 57 were confirmed to be negative. There were three false-positive and eight false-negative multi-detector row CT studies. With clinical or surgical outcomes as the reference standard, the sensitivity, specificity, and positive and negative predictive values of multi-detector row CT were 74% (23 of 31 studies), 95% (57 of 60 studies), 88% (23 of 26 studies), and 88% (57 of 65 studies), respectively. Results of ROC analysis indicated that detection of hardware complications was much lower with radiography than with multi-detector row CT (area under ROC curve, 0.84 vs 1.00; F = 4.69, df = 1, 43; P < .05).

CONCLUSION

Multi-detector row CT is an effective tool for depicting orthopedic hardware complications.

Renal Multidector Row CT

Multidetector row CT is the most recent advance in CT technology. An increased number of detector rows and more powerful x-ray tubes result in faster scanning time, increased volume coverage, and improved spatial and temporal resolution. MDCT technology allows superior image quality, decreased examination time, and the ability to perform complex multiphase vascular and three-dimensional examinations.

Multi-detector row CT scanning in Paleoanthropology at various tube current settings and scanning mode

The purpose of this study was to determine the optimal tube current setting and scanning mode for hominid fossil skull scanning, using multi-detector row computed tomography (CT). Four fossil skulls (La Ferrassie 1, Abri Pataud 1, CroMagnon 2 and Cro-Magnon 3) were examined by using the CT scanner LightSpeed 16 (General Electric Medical Systems) with varying dose per section (160, 250, and 300 mAs) and scanning mode (helical and conventional). Image quality of two-dimensional (2D) multiplanar reconstructions, three-dimensional (3D) reconstructions and native images was assessed by four reviewers using a four-point grading scale. An ANOVA (analysis of variance) model was used to compare the mean score for each sequence and the overall mean score according to the levels of the scanning parameters. Compared with helical CT (mean score=12.03), the conventional technique showed sustained poor image quality (mean score=4.17). With the helical mode, we observed a better image quality at 300 mAs than at 160 in the 3D sequences (P=0.03). Whereas in native images, a reduction in the effective tube current induced no degradation in image quality (P=0.05). Our study suggests a standardized protocol for fossil scanning with a 16 x 0.625 detector configuration, a 10 mm beam collimation, a 0.562:1 acquisition mode, a 0.625/0.4 mm slice thickness/reconstruction interval, a pitch of 5.62, 120 kV and 300 mAs especially when a 3D study is required.

Multidetector computed tomography in acute joint fractures

Conventional radiography plays an essential diagnostic role in the primary evaluation of acute joint trauma. In complex fractures, however, computed tomography (CT) is an imaging modality often used second to radiography. As a result of technical breakthroughs in the field, multidetector CT (MDCT) allows faster imaging and better temporal, spatial, and contrast resolution compared with conventional single-slice spiral CT. MDCT with multiplanar reformation is helpful in disclosing fracture patterns, particularly in complex joint fractures, where they reveal occult fractures and show the exact number of fracture components and their degree of displacement.

Multi-detector row computed tomography: imaging the coronary arteries

Over the last 2 years, multi-detector row computed tomographic (MDCT) cardiac imaging has continued to rapidly develop and evolve from the experimental research setting to become a useful clinical tool. The increasing availability of MDCT presents today's clinicians with an additional non-invasive diagnostic cardiac imaging method, in particular for the coronary arteries. With the advent and increasing clinical use of 16-detector row machines, and now with the imminent clinical emergence of 64-channel machines, the improvements in spatial and temporal resolution and sophisticated ECG-gating are allowing motion-free, fast, accurate, detailed, contrast-enhanced cardiac imaging that begins to approach the accuracy of traditional invasive diagnostic techniques. Additional diagnostic information may also be provided.

CT diagnosis of Meckel diverticulum in a paracolic internal hernia

The autopsy incidence of internal hernia has been reported to be between 0.2% and 0.9%, and these hernias are usually diagnosed on imaging due to their complications or at surgery. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract, occurring in 1% to 3% of the population according to autopsy studies. The condition also is usually diagnosed at surgery, by barium studies or scintigraphy, or on cross-sectional imaging due to complications. We present an unusual case of a large Meckel diverticulum in a right paracolic hernia diagnosed on multidetector computed tomography. This diagnosis was made after attacks of subacute intestinal obstruction with the aid of multiplanar reconstructions. This case emphasizes the role of multidetector computed tomography and postprocessing techniques such as multiplanar reconstruction in the diagnosis of bowel pathology.

Multidetector CT in shoulder fractures

The aim of this study was to assess the multi-detector computed tomography (MDCT) findings in acute shoulder traumas compared to radiographic findings in patients referred to a level one trauma center. Two hundred and ten patients (128 male, 82 female, age 16-95 years, mean age 51.7 years) underwent shoulder MDCT due to acute trauma. Three main mechanisms of injury were established: falling (113 patients, 54%), traffic accidents (36 patients, 17%) and falling from a height (12 patients, 6%). Based on MDCT, a total of 311 fractures--152 in the scapula and 159 in the proximal humerus--occurred in 191 (91%) of the 210 patients. The two most common occult fractures were lesser tubercle and coracoid process fractures. In 20 (63%) of the patients with a comminuted fracture of proximal humerus the exact number of fracture fragments was underestimated in radiographs. MDCT with multiplanar reconstructions (MPR) is a recommended complementary examination in patients with complex proximal humerus fractures where the extent of the fractures and the position or origin of dislocated fragments is not clear on radiography. This may increase the accuracy of the fracture classification and reveal occult fractures in other parts of the shoulder.

Tracheobronchomalacia: Comparison between End-expiratory and Dynamic Expiratory CT for Evaluation of Central Airway Collapse

PURPOSE

To compare dynamic expiratory and end-expiratory computed tomography (CT) for depicting central airway collapse in patients with acquired tracheobronchomalacia (TBM).

MATERIALS AND METHODS

Institutional review board approval was obtained, and informed consent was not needed. Retrospective review was performed of all patients with a CT diagnosis of TBM in a 10-month period (n = 34) who underwent evaluation of airway disease by means of three different sequences at multi-detector row CT: end inspiration, dynamic expiration, and end expiration (the latter was performed only at the levels of the aortic arch, carina, and bronchus intermedius). Fourteen patients (11 men, three women; age range, 19-79 years) who had comparable images obtained with all three sequences at any of these three levels were included in the study. The degree of airway collapse was measured by two thoracic radiologists in consensus by calculating the percentage change in the area of the airway between inspiratory and expiratory scanning. Statistical analysis was performed by using the paired t test.

RESULTS

Dynamic expiratory CT elicited a significantly greater degree of airway collapse than end-expiratory CT at all three levels (P < .005). The mean percentages of airway collapse at each of the three levels were as follows: aortic arch, 53.9% with dynamic expiration versus 35.7% with end expiration (P = .0046); carina, 53.6% with dynamic expiration versus 30.9% with end expiration (P < .0001); and bronchus intermedius, 57.5% with dynamic expiration versus 28.6% with end expiration (P = .0022).

CONCLUSION

Dynamic expiratory CT elicits a significantly greater degree of airway collapse than standard end-expiratory CT in patients with TBM.

Comparison of artifacts on coronal reformation and axial CT pulmonary angiography images using single-detector and 4- and 8-detector multidetector-row helical CT scanners

RATIONALE AND OBJECTIVES

The aim of this study is to compare the degree of stair-step artifact on coronal reformation computed tomographic (CT) pulmonary angiography images obtained using single-detector helical CT (SDCT), four-detector (4-MDCT), and eight-detector multidetector-row CT (8-MDCT) and compare the degree of motion artifact on the corresponding axial CT images.

MATERIALS AND METHODS

Three groups of consecutive patients imaged by means of CT angiography for suspected pulmonary embolus were retrospectively identified by using CT records at our institution: (1) group A (n = 38), SDCT; (2) group B (n = 36), 4-MDCT; and (3) group C (n = 74), 8-MDCT. For each case, coronal multiplanar volume reformation maximal intensity projection images were created by using a standard technique. All images were reviewed in a randomized fashion by two thoracic radiologists who were blinded to the type of CT scanner. Stair-step artifact of pulmonary arteries on coronal reformation images was graded by consensus agreement using a four-point scale (0 = no artifact to 3 = severe artifact). Axial images were assessed for six parameters of motion artifact. The sum of these grades resulted in a total motion score, with a potential range of 0 (no motion) to 12 (severe motion). Statistical analysis was performed using the Mann-Whitney test.

RESULTS

Stair-step artifacts were significantly higher for SDCT (mean, 2.9; median, 3) compared with 4-MDCT (mean, 2.2; median, 2; P < .0001) and 8-MDCT (mean, 1.5; median, 1; P < .0001). Total motion scores were significantly higher for SDCT (mean, 9.3) compared with 4-MDCT (mean, 8.4; P = .03) and 8-MDCT (mean, 6.8; P < .0001).

CONCLUSION

Stair-step artifacts are significantly higher with SDCT compared with MDCT. For MDCT, eight-detector scanners produce images with significantly less artifact than four-detector scanners.

CT colonography using 16-MDCT in the evaluation of colorectal cancer

OBJECTIVE

This study evaluated CT colonography as a method to stage colorectal cancer and detect polyps and cancers in patients with the disease.

SUBJECTS AND METHODS

Fifty-one consecutive patients thought to have colorectal cancer underwent CT colonography, following a colonoscopy, in both the prone and supine positions. The transverse CT images, multiplanar reconstruction, volume rendered, and virtual colonoscopy images, were independently interpreted by two radiologists. Disagreements were resolved by consensus. The diagnostic accuracy of TNM staging was calculated, and the sensitivity of CT colonography for the detection of cancers and polyps, compared with that of colonoscopy, was calculated using repeated colonoscopic and surgical findings as reference standards. The technical result for distention was also graded.

RESULTS

In the 51 patients, surgery and follow-up colonoscopy revealed 21 colorectal cancers (one synchronous cancer) and 41 polyps. The diagnostic accuracies of CT colonography for TNM staging were 95%, 85%, and 100% for tumor, node, and metastasis, respectively. The sensitivity of both CT colonography and initial colonoscopy for cancer detection was 100%. The overall sensitivities of CT colonography and initial colonoscopy for polyp detection were 90% and 78%, respectively (p = 0.001). The sensitivities of CT colonography for detecting polyps of 5 mm or smaller, of 6-9 mm, and of 10 mm or larger were 84%, 94%, and 100%, respectively. The mean overall technical results for the supine and prone positions were ranked as 2.80 (SD, +/- 0.4) and 2.78 (+/- 0.4), respectively, but were without statistical significance (p = 0.781).

CONCLUSION

Our preliminary data suggest that for patients with clinical suspicion of colorectal cancer, CT colonoscopy is valuable in staging the tumor and in detecting additional polyps or cancers in areas not evaluated by conventional colonoscopy.

Multi-detector row CT angiography in patients with abdominal angina

Abdominal angina (AA) is an infrequently occurring syndrome characterized by postprandial abdominal pain due to reduced blood flow to organs in the territory of the celiac trunk, superior mesenteric artery (SMA), and inferior mesenteric artery. Multi-detector row computed tomographic (CT) angiography with four- or 16-row scanners has become a primary tool for the evaluation of patients with suspected steno-occlusive diseases of the abdominal vessels. In patients with suspected AA, multi-detector row CT angiography can help evaluate the presence and degree of stenosis in the celiac trunk and SMA, demonstrate the collateral circulation, and help exclude other causes of vascular obstruction. It also allows visualization of small vessels and of vessel wall abnormalities in the absence of significant stenosis. Vessels with a complex anatomic configuration can easily be visualized with proper postprocessing techniques. This modality can also be used to follow up patients who have undergone percutaneous interventional treatment. Limitations include the lack of dynamic representation of flow abnormalities and difficulty in evaluating heavily calcified vessels. Nevertheless, multi-detector row CT angiography with appropriate postprocessing techniques is highly effective for the diagnosis, evaluation, and treatment of suspected AA. Additional studies will help further evaluate the performance and applications of this modality.

Diagnostic value of pelvic radiography in the initial trauma series in blunt trauma

The purpose of the study was to evaluate the diagnostic value of pelvic radiography in the initial trauma series when compared to multidetector CT (MDCT) findings in serious blunt trauma. Inclusion criteria were blunt trauma and pelvic radiography in the initial trauma series, followed by a whole-body MDCT. A total of 1386 patients (874 male, 512 female, age 16-91 years, mean 41 years) met the inclusion criteria. Imaging studies were evaluated retrospectively by anatomical region and classified, when possible, using the Tile classification. Based on MDCT, a total of 629 injuries occurred in 226 (16%) of these 1386 patients. Radiography depicted 405 fractures in these 226 patients, giving an overall sensitivity of 55%. In 24 patients (11%) radiography was false-negatively normal. The sensitivity of radiography was mainly good in the anteroinferior parts of the pelvis, fair in the acetabulum and ileum, and poor in the posterior ring. By MDCT 141 (62%) patients were classified using the Tile classification and by radiography 133 patients (59%) were classified. MDCT and radiography showed the same type of pelvic injury in 72 patients (59%) and the subtype in 17 patients (14%). In 48 patients (40%) the pelvis was shown to be stable by radiography but unstable by MDCT. In conclusion, the sensitivity of pelvic radiography is low, and it is not reliable for determining if the pelvic injury is stable or not.

Murine orthostatic response during prolonged vertical studies: Effect on cerebral blood flow measured by arterial spin-labeled MRI

High-field MRI scanners are, in principle, well suited for mouse studies; however, many high-field magnets employ a vertical design that may influence the physiological state of the rodent. The purpose of this study was to investigate the orthostatic response of cerebral blood flow (CBF) in mice during a prolonged MR experiment in the vertical position. Arterial spin-labeled (ASL) MRI was performed at 4.7-Tesla with a 15-cm gradient insert that allowed horizontal and vertical CBF measurements to be obtained with the same scanner. For mice in the head-up (HU) vertical position, CBF decreased by approximately 40% compared to the horizontal position, although blood pressure did not differ. Furthermore, CBF values for vertically positioned mice treated with phenylephrine remained constant while blood pressure increased. These results support the conclusion that cerebral autoregulation was intact, albeit at a lower level. Since CBF recovers to near horizontal values by volume loading with saline, it appears that a decrease in central venous pressure (CVP) leading to an increase in sympathetic tone may be a contributing mechanism for lowered CBF. This suggests that using an HU vertical position for MRI in mice may have broader implications, especially for studies that rely on CBF (such as BOLD and fMRI).

Three-dimensional imaging of thoracic diseases with multi-detector row CT

The benefits of multi-detector row CT (MDCT) relative to single-detector row helical CT are considerable. Multi-detector row CT allows shorter acquisition times, greater coverage, and superior image resolution. These factors substantially increase the diagnostic accuracy of the examination. Three-dimensional (3D) volume data from MDCT provides various unique applications on thoracic diseases. These includes isotropic viewings, use of multiplanar reformation (MPR), maximum and minimum intensity projections (MIP and minIP), and volume rendering performed from external and internal perspectives allowing the user to "fly around" and "fly through" the structures. Recent advances in 3D volume rendering put real-time, interactive virtual reality guidance of the procedures such as bronchoscopy and surgery into practice.

Multidetector computed tomography angiography of the abdomen

Multidetector computed tomography (MDCT) angiography has provided excellent opportunities for advancement of computed tomography (CT) technology and clinical applications. It has a wide range of applications in the abdomen including vascular pathologies either occlusive or aneurysmal; enables the radiologist to produce vascular mapping that clearly show tumor invasion of vasculature and the relationship of vessels to mass lesions. MDCTA can be used in preoperative planning for hepatic resection, preoperative evaluation and planning for liver transplantation. MDCTA can also provide extremely valuable information in the evaluation of ischemic bowel disease, active Crohn disease, the extent and location of collateral vessels in cirrhosis.