Transverse Computed Tomography Research Articles

Computed tomographic, magnetic resonance imaging, and cross-sectional anatomic features of the manus in cadavers of dogs without forelimb disease

OBJECTIVE-To provide a detailed description of cross-sectional anatomic structures of the manus in canine cadavers in association with corresponding features in computed tomographic (CT) and magnetic resonance (MR) images. SAMPLE POPULATION-7 cadavers of adult large-breed-type dogs (weight range, 25 to 30 kg) without forelimb disease. PROCEDURES-Forelimbs were removed from the cadavers within 4 hours after euthanasia and frozen. The right forelimbs of 3 cadavers were cut into 4-mm sections by use of a band saw; 1 limb each was sectioned in the transverse, dorsal, or sagittal plane. Sections were cleaned and then photographed. After thawing, transverse CT images of the right forelimbs of 3 additional cadavers were obtained, and the right forelimb of a seventh cadaver underwent MR imaging in the transverse, sagittal, and dorsal planes. The evaluated regions extended from the digits to the carpus. Features in CT and MR images that corresponded to clinically important anatomic structures in tissue sections were identified. RESULTS-For most of the anatomic structures evident in tissue sections, corresponding CT and MR imaging features were identified. Osseous and musculotendinous structures of the manus were readily detected in CT and MR images, whereas vascular structures were only rarely identified by use of the imaging techniques. CONCLUSIONS AND CLINICAL RELEVANCE-Results of the detailed assessment of anatomic structures of the canine manus in association with corresponding features in CT and MR images will facilitate detection of pathological conditions and be beneficial in planning surgical procedures for diseases of the manus in dogs.

64-Section multi-detector row CT in the preoperative diagnosis of peritoneal carcinomatosis: correlation with histopathological findings

To prospectively investigate the diagnostic accuracy of a 64-section multi-detector row computed tomography (CT) for the detection of peritoneal metastases, with the use of surgery and histopathological findings as the reference standard. The study cohort comprised 18 patients with peritoneal carcinomatosis who underwent multiphasic CT with a 64-section CT, 0-119 days before cytoreductive surgery. Transverse CT images along with isotropic reformatted coronal and sagittal images were prospectively and independently evaluated by one of the five staff radiologists in an unblinded fashion. The overall sensitivity, specificity, positive, and negative predictive values of CT for the detection of peritoneal metastases were, respectively, 75% (93 of 124 lesions; confidence interval [CI] 68-84), 92% (118 of 128; CI 85-96), 90% (93 of 103; CI 83-95), and 79% (118 of 149; CI 72-86). For lesions 0.5 cm in diameter or larger, CT yielded a mean sensitivity of 89% (77 of 87; CI 75-97), although sensitivity decreased to only 43% (16 of 37; CI 28-56) for lesions <0.5 cm in diameter. 64-Section CT with the addition of isotropic reformatted coronal and sagittal images is a very effective technique in the detection of peritoneal metastases of 0.5 cm in diameter or larger, although sensitivity decreases remarkably for lesions <0.5 cm in diameter.

EVALUATION OF A HEAD‐REPOSITIONER AND Z‐PLATE SYSTEM FOR IMPROVED ACCURACY OF DOSE DELIVERY

Radiation therapy requires accurate dose delivery to targets often identifiable only on computed tomography (CT) images. Translation between the isocenter localized on CT and laser setup for radiation treatment, and interfractional head repositioning are frequent sources of positioning error. The objective was to design a simple, accurate apparatus to eliminate these sources of error. System accuracy was confirmed with phantom and in vivo measurements. A head repositioner that fixates the maxilla via dental mold with fiducial marker Z-plates attached was fabricated to facilitate the connection between the isocenter on CT and laser treatment setup. A phantom study targeting steel balls randomly located within the head repositioner was performed. The center of each ball was marked on a transverse CT slice on which six points of the Z-plate were also visible. Based on the relative position of the six Z-plate points and the ball center, the laser setup position on each Z-plate and a top plate was calculated. Based on these setup marks, orthogonal port films, directed toward each target, were evaluated for accuracy without regard to visual setup. A similar procedure was followed to confirm accuracy of in vivo treatment setups in four dogs using implanted gold seeds. Sequential port films of three dogs were made to confirm interfractional accuracy. Phantom and in vivo measurements confirmed accuracy of 2 mm between isocenter on CT and the center of the treatment dose distribution. Port films confirmed similar accuracy for interfractional treatments. The system reliably connects CT target localization to accurate initial and interfractional radiation treatment setup.

Staging of T3 and T4 Gastric Carcinoma with Multidetector CT: Added Value of Multiplanar Reformations for Prediction of Adjacent Organ Invasion

To determine the added value of multiplanar reformation (MPR) images combined with computed tomographic (CT) images in staging of T4 gastric cancers. The institutional review board approved this retrospective study and waived informed consent. One hundred forty-nine consecutive patients (99 men [age range, 33-85 years; mean age, 63.1 years] and 50 women [age range, 30-85 years; mean age, 57.1 years]; age range, 30-85 years; mean age, 61.1 years) with pathologically and/or surgically confirmed T3 (n = 110) or T4 tumors (n = 39), with invasion of the transverse colon or mesocolon (n = 23), pancreas (n = 16), diaphragm (n = 4), liver (n = 3), and/or spleen (n = 1) were included. Two experienced radiologists independently reviewed 4-mm-thick transverse CT images and, 10 weeks later, reviewed both transverse CT and additional coronal and sagittal MPR images to assess tumor invasion in each of the aforementioned five adjacent organs. Receiver operating characteristic (ROC) analyses and weighted kappa statistics were obtained to evaluate reader performance and agreement in identifying tumor invasion. With addition of MPR images, the area under the ROC curve (AUC) led to a significant increase in the prediction of adjacent organ invasion in per-organ analyses (0.88 vs 0.95 for reader 1 [P = .01], 0.88 vs 0.98 for reader 2 [P < .001]) and identification of T4 tumors in per-patient analyses (0.79 vs 0.91 for reader 1 [P = .006], 0.78 vs 0.96 for reader 2 [P < .001]). In the five analyzed organs, AUC was significantly increased in regard to invasion of the transverse colon or mesocolon and pancreas; separate analysis was not performed for the diaphragm, liver, and spleen because of the small number of true invasions. Interobserver agreement increased in per-organ (kappa = 0.43 vs 0.67) and per-patient (kappa = 0.42 vs 0.62) analyses. Adding MPR images to transverse CT images improves the capability for distinguishing T3 from T4 gastric cancer and prediction of adjacent organ invasion. http://radiology.rsnajnls.org/cgi/content/full/2502071872/DC1.

Extrahepatic Collateral Artery Supply to the Tumor Thrombi of Hepatocellular Carcinoma Invading Inferior Vena Cava: The Prevalence and Determinant Factors

To retrospectively evaluate the prevalence of extrahepatic collateral artery supply to tumor thrombi of hepatocellular carcinomas (HCCs) invading the inferior vena cava (IVC) and to assess the determining factors. From February 1998 to June 2007, 82 patients with IVC tumor thrombi on computed tomography (CT) underwent angiographic evaluation of their extrahepatic collateral artery supply. Potential determining factors for extrahepatic collateral artery supply to the IVC tumor thrombi included sex, age, Child-Pugh class, history of chemoembolization, tumor factors (ie, size, number, and growth pattern), distance from primary tumor to IVC thrombi, portal vein invasion, and extent of IVC thrombi (ie, occupying more than half the IVC lumen on transverse CT image, completely filling and distending IVC lumen, or extending into the right atrium). Univariate analysis and multiple logistic regression analysis were performed. Fifty-four of the 82 patients (65.9%) had extrahepatic collateral artery supply: 47 from the right inferior phrenic artery, four from the right adrenal artery, two from the right internal mammary artery, and one from the right renal artery. The presence of extrahepatic collateral artery supply to IVC tumor thrombi showed a significant relationship with a history of chemoembolization (P = .001, odds ratio [OR] = 22.4) and distension of IVC by tumor thrombi (P = .005, OR = 9.1). IVC tumor thrombi of HCCs are frequently supplied by extrahepatic collateral arteries, the most common of which is the right inferior phrenic artery. The significant determining factors are a history of chemoembolization and the extent of IVC tumor thrombi.

Computed tomographic anatomy of the temporomandibular joint in the young horse

The equine temporomandibular joint (TMJ) and its surrounding structures can be difficult to investigate in cases with a clinical problem related to the region. Little previous attention has been given either to a computed tomographic (CT) imaging protocol for the joint or an interpretation of the structures displayed in CT images of the normal joint. To provide a CT atlas of the normal cross-sectional anatomy of the equine TMJ using frozen and plastinated sections as anatomical reference. Eight TMJs from 4 immature pure-bred Spanish horses were examined by helical CT. Scans were processed with a detailed algorithm to enhance bony and soft tissue. Transverse CT images were reformatted into sagittal and dorsal planes. Transverse, sagittal and dorsal cryosections were then obtained, photographed and plastinated. Relevant anatomic structures were identified in the CT images and corresponding anatomical sections. In the CT images, a bone window provided excellent bone detail, however, the soft tissue components of the TMJ were not as well visualised using a soft tissue window. The articular cartilage was observed as a hyperattenuating stripe over the low attenuated subchondral bone and good delineation was obtained between cortex and medulla. The tympanic and petrous part of the temporal bone (middle and inner ear) and the temporohyoid joint were seen in close proximity to the TMJ. Helical CT provided excellent images of the TMJ bone components to characterise the CT anatomy of the normal joint. Detailed information is provided that may be used as a reference by equine veterinarians for the CT investigation of the equine TMJ and serve to assist them in the diagnosis of disorders of the TMJ and related structures (middle and inner ear). The study was performed at an immature stage and further studies of mature individuals are required in order to confirm that the clinical interpretation is not affected by changes occurring with age.

A NURBS-based technique for subject-specific construction of knee bone geometry

Subject-specific finite element (FE) models of bones that form the knee joint require rapid and accurate geometry construction. The present study introduces a semi-automatic non-uniform rational B-spline (NURBS) technique to construct knee bone geometries from computed tomography (CT) images using a combination of edge extraction and CAD surface generation. In particular, this technique accurately constructs endosteal surfaces and can accommodate thin cortical bone by estimating the cortical thickness from well-defined surrounding bone. A procedure is also introduced to overcome the bifurcation at the femoral condyles during surface generation by combining transverse and sagittal plane CT data. Available voxel- and NURBS-based subject-specific construction techniques accurately capture periosteal surfaces but are limited in their ability to capture endosteal geometry. In this study, the proposed NURBS-based technique and a typical voxel mesh technique captured periosteal surfaces within an order of magnitude of image resolution. The endosteum of diaphyseal bone was also captured with similar accuracy by both techniques. However, the voxel mesh model failed to accurately capture the metaphyseal and epiphyseal endosteum due to the poor CT contrast of thin cortical bone, resulting in gross overestimation of cortical thickness. The proposed technique considered both the local and global nature of CT images to arrive at a description of cortical bone thickness accurate to within 2 pixel lengths.

Sixty-four–detector CT Angiography of Infrarenal Aortic Neck Length and Angulation: Prospective Analysis of Interobserver Variability

To quantify the interobserver variability of abdominal aortic aneurysm (AAA) neck length and angulation measurements. A total of 25 consecutive patients scheduled for endovascular AAA repair underwent follow-up 64-row computed tomographic (CT) angiography in 0.625-mm collimation. AAA neck length and angulation were determined by four blinded, independent readers. AAA neck length was defined as the longitudinal distance between the first transverse CT slice directly distal to the lowermost renal artery and the first transverse CT slice that showed at least a 15% larger outer aortic wall diameter versus the diameter measured directly below the lowermost renal artery. Infrarenal AAA neck angulation was defined as the true angle between the longitudinal axis of the proximal AAA neck and the longitudinal axis of the AAA lumen as analyzed on three-dimensional CT reconstructions. Mean deviation in aortic neck length determination was 32.3% and that in aortic neck angulation was 32.1%. Interobserver variability of aortic neck length and angulation measurements was considerable: in any reader combination, at least one measurement difference was outside the predefined limits of agreement. Assessment of the longitudinal extension and angulation of the infrarenal aortic neck is associated with substantial observer variability, even if measurement is carried out according to a standardized protocol. Further studies are mandatory to assess dedicated technical approaches to minimize variance in the determination of the longitudinal extension and angulation of the infrarenal aortic neck.

Relationships among measurements obtained by use of computed tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs

To evaluate correlations among measurements on radiographic and computed tomography (CT) images with articular cartilage microdamage in lax hip joints of dogs. 12 adult mixed-breed hounds. Pelvic CT and radiography were performed. Hip joints were harvested following euthanasia. Orthopedic Foundation for Animals (OFA) and PennHIP radiograph reports were obtained. Norberg angle (NA) and radiographic percentage femoral head coverage (RPC) were determined. Center-edge angle (CEA), horizontal toit externe angle (HTEA), ventral acetabular sector angle (VASA), dorsal acetabular sector angle (DASA), horizontal acetabular sector angle (HASA), acetabular index (AI), and CT percentage femoral head coverage (CPC) were measured on 2-dimensional CT images. Femoral head-acetabular shelf percentage was measured on sagittal 3-dimensional CT (SCT) and transverse 3-dimensional CT (TCT) images. Light microscopy was used to score joint cartilage. Relationships of OFA confirmation and PennHIP osteoarthritis scores with radiography, CT, and cartilage variables and relationships of cartilage scores with radiography and CT measurements were evaluated with Spearman rank correlations. Pearson correlation was used for relationships of distraction index (DI) with radiography, CT, and cartilage variables. Significant relationships included PennHIP osteoarthritis score with cartilage score, CEA, HTEA, DASA, AI, CPC, and TCT; OFA confirmation score with cartilage score, NA, RPC, CEA, HTEA, DASA, AI, CPC, and TCT; cartilage score with NA, RPC, CEA, HTEA, DASA, HASA, AI, and TCT; and DI with cartilage score, CEA, HTEA, DASA, HASA, AI, and CPC. CT appeared to be a valuable imaging modality for predicting cartilage microdamage in canine hip joints.

Prospectively Gated Transverse Coronary CT Angiography versus Retrospectively Gated Helical Technique: Improved Image Quality and Reduced Radiation Dose

To retrospectively compare image quality, radiation dose, and blood vessel assessability for coronary artery computed tomographic (CT) angiograms obtained with a prospectively gated transverse (PGT) CT technique and a retrospectively gated helical (RGH) CT technique. This HIPAA-compliant study received a waiver for approval from the institutional review board, including one for informed consent. Coronary CT angiograms obtained with 64-detector row CT were retrospectively evaluated in 203 clinical patients. A routine RGH technique was evaluated in 82 consecutive patients (44 males, 38 females; mean age, 55.6 years). The PGT technique was then evaluated in 121 additional patients (71 males, 50 females; mean age, 56.7 years). All images were evaluated for image quality, estimated radiation dose, and coronary artery segment assessability. Differences in image quality score were evaluated by using a proportional odds logistic regression model, with main effects for three readers, two techniques, and four arteries. The mean effective dose for the group with the PGT technique was 2.8 mSv; this represents an 83% reduction as compared with that for the group with the RGH technique (mean, 18.4 mSv; P < .001). The image quality score for each of the arteries, as well as the overall combined score, was significantly greater for images obtained with PGT technique than for images obtained with RGH technique. The combined mean image quality score was 4.791 for images obtained with PGT technique versus 4.514 for images obtained with RGH technique (proportional odds model odds ratio, 2.8; 95% confidence interval: 1.7, 4.8). The percentage of assessable coronary artery segments was 98.6% (1196 of 1213) for images obtained with PGT technique versus 97.9% (1741 of 1778) for images obtained with RGH technique (P = .83). PGT coronary CT angiography offers improved image quality and substantially reduced effective radiation dose compared with traditional RGH coronary CT angiography.

A comparative study of methods of estimating kidney length in kidney transplantation donors

Knowledge of kidney size is important for clinical assessment of renal disease. However, there are few studies on methods of assessing kidney size. The purpose of this study was to determine the usefulness of body index and radiological measurements for prediction of kidney size. One hundred and twenty five donors were enrolled. The sizes of donor kidneys obtained after nephrectomies for kidney transplantations were documented and the correlation coefficient between kidney length and body index was calculated. Kidney length was estimated from the distance between the first and third lumbar vertebrae (L1-3), intravenous pyelograms (IVPs), abdominal ultrasonography (US), and abdominal computed tomography (CT). Normal adult kidneys were 11.08 +/- 0.96 cm long, 6.25 +/- 0.67 cm wide, 4.73 +/- 0.65 cm thick and weighed 196.3 +/- 41.0 g. Correlation coefficients between kidney length and body height, body weight, body surface area and total body water content were 0.29, 0.31, 0.26, and 0.32, respectively. The difference between actual and predicted kidney lengths was -0.6 cm for L1-3, +1.2 cm for IVPs, -0.7 cm for abdominal US, -0.8 cm for transverse CT section, and -0.5 cm for coronal CT section. Abdominal coronal CT section predicted kidney length more accurately than other radiological methods, but all radiological methods were associated with prediction errors. As kidney length was correlated with body index, it is suggested that body index is the most useful and simplest method of estimating kidney size as an adjunct to treatment decisions concerning renal disease.

Hyaline Cartilage Thickness in Radiographically Normal Cadaveric Hips: Comparison of Spiral CT Arthrographic and Macroscopic Measurements

To assess spiral multidetector computed tomographic (CT) arthrography for the depiction of cartilage thickness in hips without cartilage loss, with evaluation of anatomic slices as the reference standard. Permission to perform imaging studies in cadaveric specimens of individuals who had willed their bodies to science was obtained from the institutional review board. Two independent observers measured the femoral and acetabular hyaline cartilage thickness of 12 radiographically normal cadaveric hips (from six women and five men; age range at death, 52-98 years; mean, 76.5 years) on spiral multidetector CT arthrographic reformations and on coronal anatomic slices. Regions of cartilage loss at gross or histologic examination were excluded. CT arthrographic and anatomic measurements in the coronal plane were compared by using Bland-Altman representation and a paired t test. Differences between mean cartilage thicknesses at the points of measurement were tested by means of analysis of variance. Interobserver and intraobserver reproducibilities were determined. At CT arthrography, mean cartilage thickness ranged from 0.32 to 2.53 mm on the femoral head and from 0.95 to 3.13 mm on the acetabulum. Observers underestimated cartilage thickness in the coronal plane by 0.30 mm +/- 0.52 (mean +/- standard error) at CT arthrography (P < .001) compared with the anatomic reference standard. Ninety-five percent of the differences between CT arthrography and anatomic values ranged from -1.34 to 0.74 mm. The difference between mean cartilage thicknesses at the different measurement points was significant for coronal spiral multidetector CT arthrography and anatomic measurement of the femoral head and acetabulum and for sagittal and transverse CT arthrography of the femoral head (P < .001). Changes in cartilage thickness from the periphery to the center of the joint ("gradients") were found by means of spiral multidetector CT arthrography and anatomic measurement. Spiral multidetector CT arthrography depicts cartilage thickness gradients in radiographically normal cadaveric hips.

Pulmonary Arteriovenous Malformation Treated with Embolotherapy: Systemic Collateral Supply at Multidetector CT Angiography after 2–20-year Follow-up

To retrospectively evaluate frequency of systemic arterial collateral supply to treated pulmonary arteriovenous malformations (PAVMs) in long-term follow-up with multi-detector row helical computed tomography (CT). Institutional review board approval was obtained, with waiver of informed consent. Thirty-two patients (19 male, 13 female; mean age, 43 years) underwent follow-up multi-detector row helical CT angiography of the chest (collimation, 16x0.75 mm) 2 or more years after embolotherapy of PAVMs. The study group had a history of successful embolotherapy of 53 PAVMs and a mean of 9 years of follow-up (range, 2-20 years). A search for abnormal systemic arteries was based on analysis of thin-collimated contiguous transverse CT scans and two- and three-dimensional images including maximum intensity projections and volume-rendered images. Statistical comparison was performed with the Fisher exact test (categoric variables) and Wilcoxon rank sum test (continuous variables). At CT, 13 patients (group 1) had abnormally enlarged systemic arteries and 19 patients (group 2) had no abnormal arteries. In group 1, 32 abnormally enlarged arteries were seen-five bronchial and 27 nonbronchial arteries (14 inferior phrenic, six musculophrenic, five internal mammary, two intercostal). The degree of enlargement was moderate for 26 arteries and marked for six. There were no significant differences between groups for (a) clinical characteristics of patients, including history of surgery before or after embolotherapy (P=.7); (b) anatomic structures of treated PAVMs; and (c) embolization procedures and their effectiveness. The number of patients with features suggestive of lung infarction in the days or months after embolotherapy was significantly higher in group 1 (P=.04). On CT angiograms, the number of patients with features suggestive of sequelae of lung infarction was significantly higher in group 1 (P=.02). There were no symptomatic differences attributable to systemic collateral supply between groups; in particular, there was no hemoptysis in group 1. Abnormally enlarged systemic arteries were present in 13 of 32 patients, in whom there was a significantly higher frequency of clinical and/or radiographic features suggestive of lung infarction after embolotherapy.

Comparison of Radiography and Computed Tomography to Evaluate Metacarpo/Metatarsophalangeal Joint Pathology of Paired Limbs of Thoroughbred Racehorses with Severe Condylar Fracture

To compare the orthogonal radiographic (OR) and computed tomographic (CT) appearance of paired Thoroughbred racehorse limbs with severe condylar fracture. In vitro study. Cadaveric paired limbs with severe condylar fracture (n=11 horses). Four standard radiographic and multiple transverse CT images were obtained of the fractured and contralateral limbs centering on the metacarpo/metatarsophalangeal (fetlock) joints. Radiographs and CT images were graded by 4 raters, and interobserver agreement was calculated. Imaging evaluations were supplemented by fetlock joint dissection. A consensus description of actual injury and the detection accuracy of OR and CT for that injury was determined. Results- Rater agreement for OR and CT for most pathologic features was good or excellent. OR was similar to CT for the detection of condylar and diaphyseal third metacarpal and metatarsal (MC/MT3) fractures, diaphyseal fractures of the first phalanx (P1), and fracture location on the condyle. CT was superior to OR for detection of MC/MT3 proximal fissures and articular comminution, condylar small cracks and lucencies, and proximal sesamoid fractures. OR was superior to CT for detection of proximal P1 dorsal fractures. Both OR and CT were poor at detecting palmar/planter proximal P1 fractures and coalescing cracks in the subchondral bone of MC/MT3. CT is better than OR for detection of pathology in limbs with condylar fractures, but does not detect every pathologic feature. CT provides superior information of pathology in Thoroughbred racehorses with condylar fractures.

ANATOMIC AND COMPUTED TOMOGRAPHIC ATLAS OF THE HEAD OF THE NEWBORN BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS)

The head of a newborn dolphin (Tursiops truncatus), that died shortly after birth was imaged using computed tomography (CT). Gross cross-sectional slices of the head were compared with the CT images to identify normal structures of the cranium, brain, and respiratory and digestive pathways. Labelled transverse CT images of the dolphin head are presented sequentially as a reference for normal anatomy.

Assessment of bone mineral density of the femoral head in dogs with early osteoarthritis

To compare the bone mineral density (BMD) of the proximal portion of the femur in dogs with and without early osteoarthritis secondary to hip dysplasia. 24 dogs (3 Greyhounds, 6 Labrador-Greyhound crossbreeds, and 15 Labrador Retrievers). Computed tomography (CT) of the pelvis, including a bone-density phantom, was performed for each dog. Centrally located transverse CT slices and a computer workstation were used to identify 16 regions of interest (ROIs) in the proximal portion of the femur. For each ROI, the mean Hounsfield unit value was recorded; by use of the bone-density phantom and linear regression analysis, those values were converted to equivalent BMD (eBMD). Mean eBMD values for the subchondral and nonsubchondral ROIs in dogs with and without osteoarthritis (determined at necropsy) were compared. A mixed-model ANOVA and post hoc linear contrasts were used to evaluate the effects of osteoarthritis, breed, and sex on the BMD value. At necropsy, osteoarthritis was detected in 14 hip joints in 9 dogs; all lesions included early cartilage fibrillation. After adjusting for breed and sex, eBMD in subchondral ROIs 8 and 12 (adjacent to the fovea) were 8% and 6% higher, respectively, in osteoarthritis-affected dogs, compared with unaffected dogs; in the nonsubchondral ROIs, eBMD was 10% higher in osteoarthritis-affected dogs. Compared with findings in unaffected dogs, increased eBMD in hip joints of dogs with early osteoarthritis supports a strong relationship between the subchondral and epiphyseal regions and articular cartilage in the pathogenesis and progression of osteoarthritis.

Computed tomographic anatomy of the head of the loggerhead sea turtle ( Caretta caretta)

The heads of three loggerhead sea turtles were disarticulated and imaged immediately to minimize postmortem changes and then frozen and sectioned. For computed tomography (CT) imaging, the heads were positioned in ventral recumbency. Transverse CT images with soft-tissue window were obtained from the olfactory sac region to the temporomandibular joint region. After CT imaging, the heads were sectioned and the gross sections were compared to CT images, to assist in the accurate identification of the anatomic structures. Different clinically relevant anatomic structures were identified and labelled in two series of photographs (CT images and anatomic cross-sections). CT images provided good differentiation between the bones and the soft tissues of the head. The information presented in this paper should serve as an initial reference to evaluate CT images of the head of the loggerhead sea turtle and to assist in the interpretation of lesions of this region.

Computed Tomographic Evaluation of Canine Radioulnar Incongruence In Vivo

To compare radioulnar incongruence (RUI) of normal canine elbows and elbows with arthroscopically confirmed medial compartment disease in vivo using systematic computed tomography (CT) measurements. Prospective comparison of RUI measurements in normal and dysplastic canine elbows. Right elbows of 25 medium-large breed, adult dogs with medial compartment disease and 9 medium-large breed, adult dogs with no elbow disease. Transverse CT images of proximal radioulnar articulation were reformatted to dorsal and sagittal planes. RUI in 3 locations of the forelimb's medial coronoid was measured. Arthroscopy confirmed diagnosis of medial compartment disease in the diseased group. RUI measurements of the diseased and normal elbows were compared. Cumulative statistical analysis of RUI in all planes revealed no significant difference between the normal and abnormal elbows (P = .61). The abnormal elbows had negative mean RUI at the mid (P = .56) and cranial (P = .24) coronoid regions that were not significantly different from normal elbows and mean positive RUI at the base coronoid that was significantly greater than in normal elbows (P = .00082). Canine elbows with established medial compartment disease do not have significant RUI at the medial coronoid region at the time of diagnosis when compared with normal elbows. If RUI is a significant factor in the pathophysiology of medial compartment elbow disease in the dog, it does not appear to be present at the time of diagnosis of disease. Ulnar or radial osteotomies do not appear to be indicated for restoration of normal radioulnar articular surface alignment.

Small-Bowel Obstruction: Coronal Reformations from Isotropic Voxels at 16-Section Multi–Detector Row CT

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). 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). 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). 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.

Comparison of Computed Tomographic and Standard Radiographic Determination of Tibial Torsion in the Dog

Objective— To compare the effect of internal tibial rotation on the computed tomographic (CT) and standard radiographic assessment of tibial torsion (TT) in dogs.Study Design— In vitro study.Sample Population— Cadaveric canine hind limbs (6 pairs).Methods— The cranial cruciate ligament was transected, and caudo‐cranial radiographic and transverse CT images were obtained with the femur and tibiae in a neutral position, and after 15° internal tibial rotation. Radiographic TT was determined by measuring the distance (d) between the calcaneus and the sulcus of the talus. CT determination of TT was performed using the proximal transcondylar and the distal cranial tibial axes. The distance (d) in the 2 groups and the difference in the CT determination of TT between groups were compared with a hypothetical mean value of 0 mm and 0°, respectively.Results— The mean distance (d) for the neutral radiographic group was not significantly different from 0 (P=.473); however, for the 15° group it was significantly different (P&lt;.0001). The difference in the CT determination of TT did not differ from 0 (P=.317).Conclusion— The standard radiographic technique does not discriminate between internal TT and internal rotation of the tibia. Thus, dogs with normal tibial conformation can be depicted by radiography as torsed, whereas dogs with TT may be misinterpreted as normal because of arbitrary positioning.Clinical Relevance— Lateral displacement of the medial border of the calcaneus on a caudo‐cranial radiograph should not be used as the sole arbiter of TT before surgical correction.