High-resolution Multidetector Computed Tomography Research Articles

Computed Tomography Density as a Bio-marker for Histologic Grade of Otosclerosis: A Human Temporal Bone Pathology Study.

Computed tomography (CT) density measurement can be used to objectively distinguish otosclerosis from normal bone and to determine histologic grades of otosclerosis. Otosclerosis can be seen on CT as subtle radiolucent areas. An objective radiologic measurement that corresponds to known otosclerosis pathology may improve diagnostic accuracy, and could be used as a radiologic biomarker for otosclerosis grade. A blinded, randomized evaluation of both histologic grade on histopathology slides and CT density measurement was performed on 78 human temporal bone specimens (31 with otosclerosis and 47 controls) that had undergone high-resolution multi-detector CT before histologic processing. Assessments were performed at 11 regions of interest (ROIs) in the otic capsule for each specimen. The CT density measurement mean (Hounsfield Units) ± standard deviation for all ROIs (Nos. 1-9) was 2245 ± 854 for grade 0 (no otosclerosis, n = 711), 1896 ± 317 for grade 1 (inactive otosclerosis, n = 109), and 1632 ± 255 for grades 2 and 3 combined (mixed/active otosclerosis, n 35). There was a strong inverse correlation of CT density to histologic grade at ROIs Nos. 1-5 (ANOVA, p < 0.0001). The inter-rater reliability for CT density was very good (correlation coefficient 0.87, p < 0.05). ROC curves suggested a cut-off of 2,150HU to distinguish otosclerosis from normal bone, and 1,811HU to distinguish low grade from mixed/high grade otosclerosis. In human temporal bone specimens, CT density may be used to distinguish normal bone from bone involved by otosclerosis. A higher histologic grade (i.e., indicating a more active otosclerotic focus) correlated with lower density.

Diagnostic usefulness of cone-beam computed tomography versus multi-detector computed tomography for sinonasal structure evaluation.

ObjectiveCone‐beam computed tomography (CBCT) is a promising imaging modality for sinonasal evaluation, with advantages of relatively low radiation dose, low cost, and quick outpatient imaging. Our study aimed to compare the diagnostic performance and image quality of CBCT with those of multi‐detector computed tomography (MDCT) with different slice thickness.MethodsWe retrospectively reviewed 60 consecutive patients who had undergone both CBCT and MDCT. MDCT images was reconstructed with 1 and 3 mm slice thickness. The quantitative image quality parameters (image noise, signal‐to‐noise ratio [SNR], and contrast‐to noise ratio [CNR] were calculated and compared between the two imaging modalities. Two observers (ENT surgeon and neuroradiologist) evaluated the presence of seven sinonasal anatomic variations in each patient and interobserver agreements were analyzed. The diagnostic performance of CBCT (0.3 mm) and MDCT (3 mm) was assessed and compared with that of high resolution MDCT (1 mm), which is considered as the gold standard.ResultsThe image noise was significantly higher and SNR and CNR values were lower in the CBCT (0.3 mm) group than in the MDCT groups (1 and 3 mm). The diagnostic performance of CBCT (0.3 mm) was similar to that of MDCT (1 mm) and superior to that of MDCT (3 mm). The highest interobserver agreement was for high resolution MDCT (1 mm), followed by CBCT (0.3 mm), and MDCT (3 mm).ConclusionConsidering its low radiation dose, low cost, and ease of clinical access, CBCT may be a useful imaging modality for as first line sinonasal evaluation and repeated follow up.Study design: Retrospective study in a tertiary referral university center.Level of evidence: NA.

Bone structure determined by HR-MDCT does not correlate with micro-CT of lumbar vertebral biopsies: a prospective cross-sectional human in vivo study

BackgroundOsteoporosis is characterized by a deterioration of bone structure and quantity that leads to an increased risk of fractures. The primary diagnostic tool for the assessment of the bone quality is currently the dual-energy X-ray absorptiometry (DXA), which however only measures bone quantity. High-resolution multidetector computed tomography (HR-MDCT) offers an alternative approach to assess bone structure, but still lacks evidence for its validity in vivo. The objective of this study was to assess the validity of HR-MDCT for the evaluation of bone architecture in the lumbar spine.MethodsWe conducted a prospective cross-sectional study to compare the results of preoperative lumbar HR-MDCT scans with those from microcomputed tomography (μCT) analysis of transpedicular vertebral body biopsies. For this purpose, we included patients undergoing spinal surgery in our orthopedic department. Each patient underwent preoperative HR-MDCT scanning (L1-L4). Intraoperatively, transpedicular biopsies were obtained from intact vertebrae. Micro-CT analysis of these biopsies was used as a reference method to assess the actual bone architecture. HR-MDCT results were statistically analyzed regarding the correlation with results from μCT.ResultsThirty-four patients with a mean age of 69.09 years (± 10.07) were included in the study. There was no significant correlation for any of the parameters (bone volume/total volume, trabecular separation, trabecular thickness) between μCT and HR-MDCT (bone volume/total volume: r = − 0.026 and p = 0.872; trabecular thickness: r = 0.074 and r = 6.42; and trabecular separation: r = − 0.18 and p = 0.254).ConclusionTo our knowledge, this is the first study comparing in vivo HR-MDCT with μCT analysis of vertebral biopsies in human patients. Our findings suggest that lumbar HR-MDCT is not valid for the in vivo evaluation of bone architecture in the lumbar spine. New diagnostic tools for the evaluation of osteoporosis and preoperative orthopedic planning are urgently needed.

3D cone-beam CT with a twin robotic x-ray system in elbow imaging: comparison of image quality to high-resolution multidetector CT

BackgroundElbow imaging is challenging with conventional multidetector computed tomography (MDCT), while cone-beam CT (CBCT) provides superior options. We compared intra-individually CBCT versus MDCT image quality in cadaveric elbows.MethodsA twin robotic x-ray system with new CBCT mode and a high-resolution clinical MDCT were compared in 16 cadaveric elbows. Both systems were operated with a dedicated low-dose (LD) protocol (equivalent volume CT dose index [CTDIvol(16 cm)] = 3.3 mGy) and a regular clinical scan dose (RD) protocol (CTDIvol(16 cm) = 13.8 mGy). Image quality was evaluated by two radiologists (R1 and R2) on a seven-point Likert scale, and estimation of signal intensity in cancellous bone was conducted. Wilcoxon signed-rank tests and intraclass correlation coefficient (ICC) statistics were used.ResultsThe CBCT prototype provided superior subjective image quality compared to MDCT scans (for RD, p ≤ 0.004; for LD, p ≤ 0.001). Image quality was rated very good or excellent in 100% of the cases by both readers for RD CBCT, 100% (R1) and 93.8% (R2) for LD CBCT, 62.6% and 43.8% for RD MDCT, and 0.0% and 0.0% for LD MDCT. Single-measure ICC was 0.95 (95% confidence interval 0.91–0.97; p < 0.001). Software-based assessment supported subjective findings with less “undecided” pixels in CBCT than dose-equivalent MDCT (p < 0.001). No significant difference was found between LD CBCT and RD MDCT.ConclusionsIn cadaveric elbow studies, the tested cone-beam CT prototype delivered superior image quality compared to high-end multidetector CT and showed a potential for considerable dose reduction.

Correlation of intraoperative and HRCT of temporal bone findings in CSOM

Introduction: The aim of the study was to assess diagnostic role of High Resolution Multi-detector Computed Tomography (HRMDCT) of temporal bone in the evaluation of Chronic Suppurative Otitis Media (CSOM) and to correlate intraoperative and HRCT findings in CSOM in selective cases. Material and Methods: 57 patients presented with CSOM in ENT department, referred to Radio diagnosis department were included in this study. The suspected patients were subjected to HRCT of Temporal bone using GE Bright speed Elite16 multi slice CT machine with 0.6mm plain axial and coronal slices with multi planar reformations. Results: The reported findings were correlated with clinical and surgical findings in subset of cases. Sensitivity, Specificity of HRMDCT with respect to clinical and surgical correlation in selective cases was evaluated. Among 30 surgical cases, most of them were atticoantral (53.4%) followed by tubotympanic CSOM (46.6%). On surgical correlation, HRCT has a high sensitivity (84.36%), specificity (80%), PPV of 90.4% and accuracy of 90% in the diagnosis of type of CSOM. A significant association with p value Conclusion: a good sensitivity, specificity of HRCT of temporal bone has a major role in the diagnosis of type of CSOM with respect to surgical correlation. HRCT of Temporal bone affords essential information regarding the disease extent, associated complications, aiding clinicians in deciding the appropriate surgical planning and management, thereby making HRMDCT an essential pre workup diagnostic tool. Keywords: Temporal bone, Cholesteatoma, HRCT, Facial canal dehiscence.

High-Resolution Bone Imaging for Osteoporosis Diagnostics and Therapy Monitoring Using Clinical MDCT and MRI

Osteoporosis is classified as a public health problem due to its increased risk for fragility fractures. Osteoporotic fractures, in particular spine and hip fractures, are associated with a high morbidity and mortality, and generate immense financial cost. The World Health Organisation (WHO) based the diagnosis of osteoporosis on the measurement of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA). However, BMD values of subjects with versus without osteoporotic fractures overlap. Furthermore, it was reported that the anti-fracture effects of drugs could be only partially explained by their effects on BMD. Bone strength reflects the integration of BMD and bone quality. The later can be partly determined by measurements of bone microstructure. Therefore, substantial research efforts have been undertaken to assess bone microstructure by using high-resolution imaging techniques, including high-resolution peripheral quantitative computed tomography (hr-pQCT), high-resolution multi-detector computed tomography (MDCT), and high-resolution magnetic resonance imaging (MRI). Clinical MDCT and MRI systems are broadly available and allow an adequate depiction of the bone microstructure at the clinically most important fracture sites, i.e. radius, spine and hip. Bone microstructure parameters and finite element models can be computed in high-resolution MDCT and MR images. These measurements improved the prediction of bone strength beyond the DXA-derived BMD and revealed pharmacotherapy effects, which are partly not captured by BMD. Therefore, high-resolution bone imaging using clinical MDCT and MRI may be beneficial for osteoporosis diagnostics and allow a highly sensitive monitoring of drug treatment, which plays an important role in the prevention of fragility fractures.

Radiological diagnosis and staging of hilar cholangiocarcinoma

Hilar cholangiocarcinoma is a rare malignant tumor arising from the epithelium of the bile ducts. Surgery is still the only chance of potentially curative treatment in patients with perihilar cholangiocarcinoma. However, radical resection requires aggressive surgical strategies that should be tailored optimally according to the location, size and vascular invasion of the tumors. Accurate diagnosis and staging of these tumors is therefore critical for optimal treatment planning and for determining a prognosis. Multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and MR cholangiography are useful tools, both to diagnose and stage hilar cholangiocarcinoma. Modern imaging techniques allow accurate detection of the level of obstruction and the longitudinal and radial spread of the tumor. In addition, high-resolution MDCT and MR provide specific radiographic features to determine vascular involvement of anatomic structures, such as the hepatic artery or the portal vein, which are critical to decide the surgical strategy. Finally, radiological staging allows detection of patients with distant metastasis in the liver or peritoneum who will not benefit from a surgical approach.

Three-dimensional reconstruction of multidetector computed tomography images of paranasal sinuses of New Zealand rabbits

This study was conducted to produce a 3-dimensional reconstruction using multidetector computed tomography (MDCT) images of the anatomic structures forming the paranasal sinuses of New Zealand rabbits and to present biometric properties of the sinuses and conchae. A total of 16 adult New Zealand rabbits, comprising 8 males and 8 females, were included in the study. After high-resolution MDCT images of the paranasal sinuses were obtained, they were reconstructed using a 3-dimensional modeling program (Mimics) by overlapping the images and the biometric measurements of the structures forming the paranasal sinuses. The maxillary sinuses of New Zealand rabbits were made up of 2 compartments. It was also observed that their conchae were more developed with an uneven structure. The frontal sinus and sphenoid sinus were not seen and the ethmoid sinus was not observed. There was not a significant statistical difference between sinus and conchae constituting the right and left paranasal sinuses of the same sex; however, a significant statistical difference was observed between the sexes (P < 0.05). This study’s data can be used for purposes of modern anatomy education and research and may form a basis as a model for future studies to be performed on the paranasal sinuses.

High Resolution Multi Detector Computed Tomography of Temporal Bone: Our Experience in a Tertiary Care Service Hospital

High resolution multi detector computed tomography (HRMDCT) is an excellent tool for evaluation of a variety of congenital and acquired conditions affecting the temporal bones. We describe our experience of HRMDCT of temporal bones of 145 patients in a tertiary care and teaching hospital of Armed Forces Medical Services of India over a period of three and half years. Hearing loss was the most frequent indication for HRMDCT and congenital bilateral profound sensorineural hearing loss for evaluation prior to possible cochlear implant formed the single largest group (62, 42%) among all indications for HRMDCT of temporal bones. Major vestibule-cochlear and semicircular canal anomalies were noted in 11 such cases. Seven patients of microtia were studied and all had positive CT scan findings. All patients of vertigo had normal HRCT study. Extent of temporal bone injuries and inflammatory conditions were clearly delineated in all cases. Thinner collimations allowing image reconstructions in planes of anatomical interest with near isotropic resolution has been a major advantage of HRMDCT of temporal bones.

Automatic definition of the central-chest lymph-node stations

Lung cancer remains the leading cause of cancer death in the United States. Central to the lung-cancer diagnosis and staging process is the assessment of the central-chest lymph nodes. This assessment requires two steps: (1) examination of the lymph-node stations and identification of diagnostically important nodes in a three-dimensional (3D) multidetector computed tomography (MDCT) chest scan; (2) tissue sampling of the identified nodes. We describe a computer-based system for automatically defining the central-chest lymph-node stations in a 3D MDCT chest scan. Automated methods first construct a 3D chest model, consisting of the airway tree, aorta, pulmonary artery, and other anatomical structures. Subsequent automated analysis then defines the 3D regional nodal stations, as specified by the internationally standardized TNM lung-cancer staging system. This analysis involves extracting over 140 pertinent anatomical landmarks from structures contained in the 3D chest model. Next, the physician uses data mining tools within the system to interactively select diagnostically important lymph nodes contained in the regional nodal stations. Results from a ground-truth database of unlabeled lymph nodes identified in 32 MDCT scans verify the system's performance. The system automatically defined 3D regional nodal stations that correctly labeled 96% of the database's lymph nodes, with 93% of the stations correctly labeling 100% of their constituent nodes. The system accurately defines the regional nodal stations in a given high-resolution 3D MDCT chest scan and eases a physician's burden for analyzing a given MDCT scan for lymph-node station assessment. It also shows potential as an aid for preplanning lung-cancer staging procedures.

Quantification of regional calcium burden in chronic total occlusion by 64-slice multi-detector computed tomography and procedural outcomes of percutaneous coronary intervention

One of the most important reasons for failure of percutaneous coronary intervention (PCI) in chronic total occlusion (CTO) is calcified plaque, which either prevents passage of guide wire or ruptures after balloon inflation. We sought to evaluate whether quantified calcium contents of CTO on multi-detector computed tomography (MDCT) correlate with immediate procedural outcomes. Sixty-four patients with 72 CTO lesions who underwent 64-slice MDCT prior to PCI were investigated. The lesions were divided into 2 groups according to procedural outcomes (55 lesions with PCI-success group, 17 lesions with PCI-failure group). Clinical, angiographic and MDCT parameters, including regional calcium volume (RCaV), regional calcium score (RCaS), regional calcium equivalent mass (RCaEq), and relative calcium area at the most calcified cross section of CTO (%CaS/CSA), were compared between the two groups. The duration of CTO was shorter in PCI-success group than PCI-failure group (7.16 ± 10.5 vs 15.59 ± 14.92 months, p=0.011), and the procedural success rate was 76.3%. Regional calcium-related parameters (RCaV 52.86 ± 58.39 vs 7.26 ± 15.27 mm(3), p<0.001; RCaS 72.71 ± 78.4 vs 9.66 ± 20.2, p<0.001; RCaEq 12.58 ± 12.97 vs 1.84 ± 3.716 mgCaHA, p<0.001; %CaS/CSA 53.9 ± 20.3 vs 30.4 ± 17.1%, p=0.009) in the occluded segment were higher and the occlusion length was longer (37.44 ± 27.48 vs 22.00 ± 18.04 mm, p<0.021) in PCI-failure group compared to PCI-success group. Multivariate regression analysis showed that only %CaS/CSA was a significant determinant of PCI-failure. Precise quantification of regional calcification and measurement of the occluded segment by high resolution MDCT can deliver important information for predicting procedural outcomes in PCI of CTO.

Conventional High-resolution CT Versus Contiguous Multidetector CT in the Detection of Bronchiolitis Obliterans Syndrome in Lung Transplant Recipients

To compare the detection rate of pulmonary abnormalities between conventional high-resolution computed tomography (HRCT) and high-resolution multidetector computed tomography (MDCT) in lung transplant recipients and to correlate a composite computed tomography (CT) score with bronchiolitis obliterans syndrome (BOS) stage. Twenty-four lung transplant recipients (12 single/12 double lung transplants, 13 males/11 females, mean age: 53 y, range: 28 to 71) underwent contiguous 16-slice high-resolution MDCT of the lungs at maximal inspiration and maximal expiration. Eight reformatted image sets were reconstructed: (i) contiguous 1-mm slice MDCT image set in the transverse, sagittal, and coronal image planes at maximal inspiration; (ii) contiguous 1-mm slice MDCT image set in the transverse, sagittal, and coronal image planes at maximal expiration; (iii) conventional HRCT image set of 1-mm slices every 10 mm at maximal inspiration; and (iv) conventional expiratory HRCT of 1-mm slices at 3 selected levels at maximal expiration. Individual pulmonary abnormalities were added to give a composite CT score. Individual abnormalities and the composite CT score were correlated with BOS stage, as based on functional testing of airflow obstruction, for each of the 8 image sets. Transverse, sagittal, and coronal MDCT correlated significantly with BOS stage (R=0.46, 0.49, 0.52, respectively), whereas conventional HRCT did not. Multiple regression analysis demonstrated that transverse MDCT was the only independent predictor of BOS stage (R=0.33, P<0.01). Interobserver agreement for composite CT scores for HRCT, transverse, sagittal, and coronal MDCT were R2=0.89, 0.87, 0.83 and 0.80, respectively. Interobserver agreement for individual abnormalities was better with MDCT than with conventional HRCT. In lung transplant recipients, high-resolution MDCT detects significantly more pulmonary abnormalities and has better interobserver agreement than conventional HRCT and is an independent predictor of BOS stage.

Stereolithographic reproduction of complex cardiac morphology based on high spatial resolution imaging

Precise knowledge of cardiac anatomy is mandatory for diagnosis and treatment of congenital heart disease. Modern imaging techniques allow high resolution three-dimensional (3D) imaging of the heart and great vessels. In this study stereolithography was evaluated for 3D reconstructions of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) data. A plastinated heart specimen was scanned with MDCT and after segmentation a stereolithographic (STL) model was produced with laser sinter technique. After scanning the STL model with MDCT these data were compared with those of the original specimen after rigid registration using the iterative closest points algorithm (ICP). The two surfaces of the original specimen and STL model were matched and the symmetric mean distance was calculated. Additionally, the heart and great vessels of patients (age range 41 days-21 years) with congenital heart anomalies were imaged with MDCT (n=2) or free breathing steady, state free-precession MRI (n=3). STL models were produced from these datasets and the cardiac segments were analyzed by two independent observers. All cardiac structures of the heart specimen were reconstructed as a STL model within sub-millimeter resolution (mean surface distance 0.27+/-0.76 mm). Cardiac segments of the STL patient models were correctly analyzed by two independent observers compared to the original 3D datasets, echocardiography (n=5), x-ray angiography (n=5), and surgery (n=4). High resolution MDCT or MRI 3D datasets can be accurately reconstructed using laser sinter technique. Teaching, research and preoperative planning may be facilitated in the future using this technique.

Contrast-Enhanced Multidetector Computed Tomography Viability Imaging After Myocardial Infarction

The ability to distinguish dysfunctional but viable myocardium from nonviable tissue has important prognostic implications after myocardial infarction. The purpose of this study was to validate the accuracy of contrast-enhanced multidetector computed tomography (MDCT) for quantifying myocardial necrosis, microvascular obstruction, and chronic scar after occlusion/reperfusion myocardial infarction. Ten dogs and 7 pigs underwent balloon occlusion of the left anterior descending coronary artery (LAD) followed by reperfusion. Contrast-enhanced (Visipaque, 150 mL, 325 mg/mL) MDCT (0.5 mm x 32 slice) was performed before occlusion and 90 minutes (canine) or 8 weeks (porcine) after reperfusion. MDCT images were analyzed to define infarct size/extent and microvascular obstruction and compared with postmortem myocardial staining (triphenyltetrazolium chloride) and microsphere blood flow measurements. Acute and chronic infarcts by MDCT were characterized by hyperenhancement, whereas regions of microvascular obstruction were characterized by hypoenhancement. MDCT infarct volume compared well with triphenyltetrazolium chloride staining (acute infarcts 21.1+/-7.2% versus 20.4+/-7.4%, mean difference 0.7%; chronic infarcts 4.15+/-1.93% versus 4.92+/-2.06%, mean difference -0.76%) and accurately reflected morphology and the transmural extent of injury in all animals. Peak hyperenhancement of infarcted regions occurred approximately 5 minutes after contrast injection. MDCT-derived regions of microvascular obstruction were also identified accurately in acute studies and correlated with reduced flow regions as measured by microsphere blood flow. The spatial extent of acute and healed myocardial infarction can be determined and quantified accurately with contrast-enhanced MDCT. This feature, combined with existing high-resolution MDCT coronary angiography, may have important implications for the comprehensive assessment of cardiovascular disease.

Noninvasive detection of coronary atherosclerotic plaque by multidetector row computed tomography

Coronary artery disease continues to be one of the leading causes of death and disability around the globe, challenging the efficacy of currently applied schemes to predict the risk for future coronary events. In fact, algorithms such as the Framingham risk score that are based on traditional risk factors like hypertension and dyslipidemia are not very sensitive, leaving a majority of the population at intermediate risk. Advances in multidetector computed tomography (MDCT) technology with submillimeter slice collimation (approximately 0.6 mm) and high temporal resolution now permit contrast-enhanced imaging of the coronary artery lumen and wall in a single breath hold. The current generation of MDCT provided in-plane resolution of 0.5 mm and a temporal resolution of 210 ms. The simultaneous acquisition of 16/64 parallel cross-sections reduces image acquisition time to about 10-20s using 60-80 ml of contrast agents to opacify the coronary artery lumen. CT imaging for coronary calcification is an established method with low radiation exposure. The amount of calcification is expressed as an Agatston Score (AS). The presence and amount of coronary calcification significantly increases the relative risk for future coronary events, independent from traditional risk factors (risk ratio 8.7 [95% Cl, 2.7-28.1]). Especially, individuals with a high AS (>400) who are at intermediate 10-y Framingham event risk may benefit from this additional risk stratification. However, calcification is rarely present in children and adolescents. However, there is a growing body of evidence suggesting that contrast-enhanced MDCT can detect both calcified and noncalcified plaques with high sensitivity and specificity for the detection of plaques > 0.5 mm when compared to intravascular ultrasound. Moreover, initial data suggest that plaque characteristics such as plaque area, volume, quantify and coronary plaque remodeling index can be quantified in good agreement with IVUS. The composition of noncalcified plaque may be further stratified into predominantly fibrous or lipid-rich plaque. Noncalcified plaque may be present already in children and adolescents with multiple risk factors. The available data indicate that high resolution MDCT can reliably detect, quantify and characterize calcified and noncalcified coronary atherosclerotic plaque. With MDCT, we now have a unique opportunity to study the natural history and response to therapy of noncalcified coronary plaques, which may be already present in obese children or children with multiple risk factors.

Failure of Standard Imaging to Detect a Cervical Fracture in a Patient With Ankylosing Spondylitis

Retrospective case study of 38-year-old male with ankylosing spondylitis who presented with a Brown-Séquard syndrome following a fall and an occult fracture on initial spinal imaging studies. To review the recommended imaging protocol in a patient with ankylosing spondylitis and a suspected cervical spine fracture. Plain radiographic imaging using orthogonal views can detect the majority of spinal fractures. However, fracture identification is particularly difficult in patients with ankylosing spondylitis. Of the various contemporary imaging methods, [magnetic resonance imaging (MRI), computed tomography (CT), nuclear scanning] high-definition multidetector CT scanning is the most useful in identifying subtle fractures, but in metabolic bone diseases the utility of these methods is unknown. Retrospective radiographic evaluation of imaging studies of ankylosing spondylitis patient with occult fracture by five spine surgeons and neuroradiologists, followed with detailed review and interpretation of literature concerning present radiology techniques and methods to isolate occult fractures. Initial imaging studies, including plain radiographs of the spinal axis, cervical and thoracic single-detector CT with reconstructed images, and MRI, were unremarkable in detecting an occult cervical spine fracture in a patient with ankylosing spondylitis and a spinal cord injury following a fall. The patient was placed empirically in a halo orthosis and a high definition multidetector CT scan was obtained. This study demonstrated a transverse fracture through the fused C6-C7 spinal level. Occult fractures in ankylosing spondylitis may not be apparent on routine plain radiographic and MRI studies. In the setting of ankylosing spondylitis, a high index of suspicion must be maintained in all patients presenting with spinal pain following even minor trauma. High-resolution multidetector CT imaging appears to be more sensitive and accurate in the diagnosis of fractures in this patient subgroup than other contemporary imaging methods.

Improved pelvicalyceal visualization with multidetector computed tomography urography; comparison with helical computed tomography

Our aim was to compare the quality of pelvicalyceal visualization on computed tomography (CT) urography using a small intravenous contrast material dose, hydration, and high-resolution multidetector CT (MDCT) with that of conventional helical CT. The test (MDCT) group (49 consecutive patients, 98 kidneys) was scanned 5 min following an intravenous bolus of 30 ml of iodinated contrast material. The control (helical CT) group (50 consecutive patients, 95 kidneys) was scanned 5 min following injection of 120-150 ml of intravenous contrast material. Enhancement and quality of calyceal detail were measured using a five-scale grading system (1 for no detail, 5 for cupped calyces). Calyceal attenuation was substantial in both groups (more than 220 Hounsfield units, HU) but less in the test group compared with the control group (mean 475 and 920 HU, respectively), p<0.0001. In the test group, the calyceal attenuation was less than 500 HU in the majority of cases (65/98 kidneys), while the opposite was true for the control group, where calyceal attenuation was more than 750 HU in 50/95 kidneys (p<0.001). The quality of calyceal detail was 3.4/5 in the test group compared with 1.8/5 in the control group (p<0.0001). The combination of hydration, low-contrast dose, and the high image resolution achieved with MDCT significantly improves calyceal visualization in CT urography.