Postcontrast Computed Tomography Images Research Articles

Intra- and interobserver agreement in computed tomography localization of primary nonhematopoietic hepatic masses and comparison with surgical and histopathological outcomes in 21 cats.

Computed tomography (CT) is commonly used in the staging of hepatic masses and for liver lobectomy planning. Mass location is an important factor in determining the feasibility of resection, including surgical technique and the likelihood of surgical complications. The objectives of this retrospective descriptive cross-sectional, observer agreement, method comparison study were to assess the reliability of CT in correctly determining the hepatic division and lobar site of origin of feline primary nonhematopoietic hepatic masses, compared with surgically confirmed locations. Furthermore, it provides an overview of the types and locations of liver masses found in a cohort of cats. Pre- and postcontrast CT images of 21 cats were independently and simultaneously reviewed by two observers. Intra- and interobserver agreements and descriptive statistics on demographic and histological diagnoses were calculated. Based on surgical assessment, it was found that masses most frequently originated from the left hepatic division (13/24, 54%). The most frequent lobar origins were the left lateral (8/24, 33%), left medial (5/24, 21%), and right medial lobes (5/24, 21%). No masses were found originating from the right lateral lobe. CT correctly determined hepatic division and lobar origin in 76% of cases, with good-to-excellent intra- and interobserver agreement. The hepatic division had higher agreements overall for both observers. Most of the masses were benign (17/21, 81%), and the most prevalent histological diagnoses were biliary cystadenoma (11/21, 52%) and hepatocellular adenoma (6/21, 29%). Findings suggest that postcontrast CT is a reliable method for correctly determining hepatic mass division and lobar origin in cats.

Deep Learning Algorithm for Fully Automated Detection of Small (≤4 cm) Renal Cell Carcinoma in Contrast-Enhanced Computed Tomography Using a Multicenter Database.

Renal cell carcinoma (RCC) is often found incidentally in asymptomatic individuals undergoing abdominal computed tomography (CT) examinations. The purpose of our study is to develop a deep learning-based algorithm for fully automated detection of small (≤4 cm) RCCs in contrast-enhanced CT images using a multicenter database and to evaluate its performance. For the algorithmic detection of RCC, we retrospectively selected contrast-enhanced CT images of patients with histologically confirmed single RCC with a tumor diameter of 4 cm or less between January 2005 and May 2020 from 7 centers in the Japan Medical Image Database. A total of 453 patients from 6 centers were selected as dataset A, and 132 patients from 1 center were selected as dataset B. Dataset A was used for training and internal validation. Dataset B was used only for external validation. Nephrogenic phase images of multiphase CT or single-phase postcontrast CT images were used. Our algorithm consisted of 2-step segmentation models, kidney segmentation and tumor segmentation. For internal validation with dataset A, 10-fold cross-validation was applied. For external validation, the models trained with dataset A were tested on dataset B. The detection performance of the models was evaluated using accuracy, sensitivity, specificity, and the area under the curve (AUC). The mean ± SD diameters of RCCs in dataset A and dataset B were 2.67 ± 0.77 cm and 2.64 ± 0.78 cm, respectively. Our algorithm yielded an accuracy, sensitivity, and specificity of 88.3%, 84.3%, and 92.3%, respectively, with dataset A and 87.5%, 84.8%, and 90.2%, respectively, with dataset B. The AUC of the algorithm with dataset A and dataset B was 0.930 and 0.933, respectively. The proposed deep learning-based algorithm achieved high accuracy, sensitivity, specificity, and AUC for the detection of small RCCs with both internal and external validations, suggesting that this algorithm could contribute to the early detection of small RCCs.

Diversity of lymphatic flow in patients with lung cancer revealed by computed tomography lymphography

This study was conducted to verify the optimal extent of lymph node dissection or sampling during lung cancer surgery based on the sentinel node (SN) map created by computed tomography (CT) lymphography. From April 2010 to January 2015, patients with clinical stage I non-small-cell lung cancer, who were candidates for lobectomy or segmentectomy with standard hilar and mediastinal lymph node dissection, and in whom bronchus reached the tumour, were enrolled. An ultrathin bronchoscope was inserted to the target bronchus under the guidance of virtual bronchoscopic navigation images. CT images of the chest were obtained 30 s after 2.5 ml of iopamidol was injected. SNs were identified when the maximum CT attenuation value of the lymph nodes on postcontrast CT images increased by 30 Hounsfield units or more compared with the precontrast images. Patients underwent lobectomy with standard lymph node dissection. SNs were identified in 36 (87.8%) of the 41 patients. The average number of SNs was 1.6 (range, 1-4). There was 1 false negative case; therefore, the accuracy of SN identification was 97.2% (35/36). In 5 (13.9%) of 36 patients, SNs were outside the lobe-specific lymph node station range (#11i from right S1, #7 from right S1, #4R from right S8, #12u from right S8, #7 and #12l from left S1 + 2). CT lymphography demonstrated the diversity of lymphatic spreading patterns and there were cases in which lymph flows are found outside the lymph node dissection range.

Non-invasive multi-channel deep learning convolutional neural networks for localization and classification of common hepatic lesions.

PurposeMachine learning techniques, especially convolutional neural networks (CNN), have revolutionized the spectrum of computer vision tasks with a primary focus on supervised and labelled image datasets. We aimed to assess a novel method to segment the liver from the abdomen computed tomography (CT) image using the CNN network, and to train a unique method to locate and classify liver lesion pre-histological findings using multi-channel deep learning CNN (MDL-CNN).Material and methodsThe post-contrast CT images of the liver with a resolution of 0.625 mm were chosen for the study. In a random method, 50 examples of each hepatocellular carcinomas, metastases tumours, haemangiomas, hepatic cysts were chosen and evaluated.ResultsThe dice score quantitatively analyses the similarity of segmentation results with the training dataset. In the first CNN model for segmenting the liver, the dice score was 96.18%. The MDL-CNN model yielded 98.78% accuracy in classification, and the dice score for locating liver lesions was 95.70%. Additionally, the performance of this model was compared to various other existing models.ConclusionsAccording to our study, the machine learning approach can be successfully implemented to segment the liver and classify lesions, which will help radiologists impart better diagnosis.

Radiogenomics of neuroblastoma in pediatric patients: CT-based radiomics signature in predicting MYCN amplification.

To construct a CT-based radiomics signature and assess its performance in predicting MYCN amplification (MNA) in pediatric patients with neuroblastoma. Seventy-eight pediatric patients with neuroblastoma were recruited (55 in training cohort and 23 in test cohort). Radiomics features were extracted automatically from the region of interest (ROI) manually delineated on the three-phase computed tomography (CT) images. Selected radiomics features were retained to construct radiomics signature and a radiomics score (rad-score) was calculated by using the radiomics signature-based formula. A clinical model was established with clinical factors, including clinicopathological data, and CT image features. A combined nomogram was developed with the incorporation of a radiomics signature and clinical factors. The predictive performance was assessed by receiver operating characteristics curve (ROC) analysis and decision curve analysis (DCA). The radiomics signature was constructed using 7 selected radiomics features. The clinical radiomics nomogram, which was based on the radiomics signature and two clinical factors, showed superior predictive performance compared with the clinical model alone (area under the curve (AUC) in the training cohort: 0.95 vs. 0.82, the test cohort: 0.91 vs. 0.70). The clinical utility of clinical radiomics nomogram was confirmed by DCA. This proposed CT-based radiomics signature was able to predict MNA. Combining the radiomics signature with clinical factors outperformed using clinical model alone for MNA prediction. • A CT-based radiomics signature has the ability to predict MYCN amplification (MNA) in neuroblastoma. • Both pre- and post-contrast CT images are valuable in predicting MNA. • Associating the radiomics signature with clinical factors improved the predictive performance of MNA, compared with clinical model alone.

CT imaging features of the normal parathyroid gland in the dog.

Aim of our prospective pilot study was to assess the feasibility of computed tomography (CT) to visualize the normal parathyroid gland in dogs and provide a description of its CT appearance. A total of 25 dogs, which received CT imaging including the neck region for diseases unrelated to the thyroid or parathyroid glands, were enrolled. Inclusion criteria were a normal physical examination, an unremarkable complete blood count and serum chemistry profile. Pre and post contrast CT images were acquired using a 16-slice helical scanner with an 18 cm field of view, 1 mm slice thickness and a 512 × 512 matrix. Post contrast images were obtained 30-45 seconds following contrast medium injection (early venous phase). CT-images were independently reviewed by 2 radiologists. Visibility of the parathyroid gland was recorded and inter-observer agreement was calculated. For all visualized parathyroid glands the following parameters were assessed: size, density in Hounsfield units (HU) on pre and post contrast images, density of the thyroid gland and border definition (excellent, moderate, poor). Only 20 respectively 25 parathyroid glands could be visualized by the 2 observers. The number did not vary between pre and post contrast images. The inter-observer agreement for the identification was fair (κ = 0.40). Length, width and height (mean ± standard deviation) of the parathyroid gland were 4.2 × 2.5 × 2.9 mm ± 1.3 × 0.8 × 1.0 mm. The density was 39.7 ± 20.6 HU on pre contrast images and 103.1 ± 47.1 HU on post contrast images, thus the organ was hypoattenuating compared to the thyroid gland on pre (166.7 ± 34.3 HU) and post contrast (234.0 ± 60.1 HU) images. This study offers the first description of the CT appearance of the presumed normal canine parathyroid gland. However, the overall visibility was poor. Despite the overall poor visibility of the parathyroid gland it was occasionally visible and its CT dimensions were larger as described for ultrasound in this group of dogs, which showed no clinical signs of hyperparathyroidism. Thus, visibility of the parathyroid gland on CT may not necessarily imply parathyroid disease. However, further research is necessary.

Malignant perineal tumors in dogs: the contribution of computed tomography for staging and surgical planning

ABSTRACT: The contribution of computed tomography for staging and surgical planning of malignant perineal tumors in dogs is discussed. Five dogs diagnosed with malignant perineal neoplasms underwent to computed tomography (CT) examination. The CT image enabled investigation of cleavage planes between neoplastic lesions and adjacent structures such as the rectum, anus, vagina, urethra and perineal muscles. Accurate assessment regional lymph nodes and adjacent bone structures was also possible. All tumors evaluated in this region presented heterogeneous appearance in pre and postcontrast CT images, but only the anal sac adenocarcinomas presented lymphadenopathy. Computed tomography proved to be a valuable tool for tumor staging and determination of lesion extension and invasion of adjacent tissues, providing significant contributions to clinical and surgical therapeutic planning.

Computed tomographic appearance of abdominal lymph nodes in healthy cats.

BackgroundComputed tomography (CT) is commonly used in veterinary medicine and plays an important role in disease identification and cancer staging. Identification of abnormal abdominal lymph nodes is important for clinical, therapeutic, and prognostic decision making. No published study describes the CT appearance of abdominal lymph nodes in healthy cats.Hypothesis/ObjectivesAll abdominal lymph centers will be identified on CT with the majority of lymph nodes being elongated and homogenously contrast enhancing.AnimalsSixteen healthy cats without clinical or biochemical evidence of disease.MethodsPrecontrast and postcontrast CT images of sedated healthy cats were used to identify the presence and descriptive characteristics of intra‐abdominal lymph nodes. These assessments then were compared with patient characteristics to identify possible correlations.ResultsAbdominal lymph nodes were readily identified on CT with caudal mesenteric, colic, hepatic, inguinal, and pancreaticoduodenal lymph nodes identified in 16/16 cats. Lymph node size and shape varied among lymph centers with nearly all lymph nodes homogeneously contrast enhancing in 515/525. Significant negative correlations were identified between age and length (P = .0166) and width (P = .0387) of abdominal lymph nodes as well as age and number of sacral lymph nodes (P = .0493). Intranodal fat was present in 18/525 lymph nodes.Conclusions and Clinical ImportanceCT readily permitted identification and characterization of feline abdominal lymph nodes. This study provides subjective and objective data on the CT characteristics of abdominal lymph nodes in 16 healthy cats, with younger cats having larger abdominal lymph nodes and a higher number of sacral lymph nodes.

Influence of Contrast Administration on Computed Tomography-Based Analysis of Visceral Adipose and Skeletal Muscle Tissue in Clear Cell Renal Cell Carcinoma.

Computed tomography (CT) scans are being utilized to examine the influence of skeletal muscle and visceral adipose quantity and quality on health-related outcomes in clinical populations. However, little is known about the influence of contrast administration on these parameters. Precontrast, arterial, and 3-minute postcontrast CT images of 45 patients with clear cell renal cell carcinoma were downloaded from The Cancer Imaging Archive and retrospectively analyzed for visceral adipose cross-sectional area (CSA) and density, and muscle CSA and density at the third lumbar vertebrae. Low muscle CSA index was defined as ≤38.9cm2 /m2 for women and ≤55.4cm2 /m2 for men. Low muscle density was defined as <41 Hounsfield units (HU) for body mass index (BMI) <24.9kg/m2 and <33 HU for BMI ≥25.0kg/m2 . In both the arterial and 3-minute phases, contrast administration decreased visceral adipose CSA (-20.9 and -20.9cm2 ; P < .001) and increased visceral adipose density (4.8 and 5.8 HU; P < .001), relative to precontrast images. Muscle CSA index marginally increased in the arterial (0.6cm2 /m2 ; P = .007) and 3-minute phases (0.8cm2 /m2 ; P < .001). This likely represents clinically insignificant changes because it does not alter the identification of low muscle CSA (44.4% vs 42.2%; P = 1.00). Skeletal muscle density increased in the arterial (6.4 HU; P < .001) and 3-minute phases (8.7 HU; P < .001), which altered the identification of low muscle density (6.7% vs 31.1%; P < .001). Future analyses should consider the phase of contrast during CT imaging because it may alter the interpretations of several parameters.

Can malignant and inflammatory pleural effusions in dogs be distinguished using computed tomography?

Computed tomography (CT) is the primary imaging modality used to investigate human patients with suspected malignant or inflammatory pleural effusion, but there is a lack of information about the clinical use of this test in dogs. To identify CT signs that could be used to distinguish pleural malignant neoplasia from pleuritis, a retrospective case-control study was done based on dogs that had pleural effusion, pre- and postcontrast thoracic CT images, and cytological or histopathological diagnosis of malignant or inflammatory pleural effusion. There were 20 dogs with malignant pleural effusion (13 mesothelioma, 6 carcinoma; 1 lymphoma), and 32 dogs with pleuritis (18 pyothorax; 14 chylothorax). Compared to dogs with pleuritis, dogs with malignant pleural effusions were significantly older (median 8.5 years vs. 4.9 years, P = 0.001), more frequently had CT signs of pleural thickening (75% vs.44%, P = 0.04), tended to have thickening of the parietal pleura only (65% vs. 13%, P = 0.01) and had more marked pleural thickening (median 3mm vs. 0mm, P = 0.01). Computed tomography signs of thoracic wall invasion were observed only in dogs with malignant pleural effusions (P = 0.05). There were no significant differences in pleural fluid volume, distribution or attenuation, degree of pleural contrast accumulation, amount of pannus, or prevalence of mediastinal adenopathy. Although there was considerable overlap in findings in dogs with malignant pleural effusion and pleuritis, marked thickening affecting the parietal pleural alone and signs of thoracic wall invasion on CT support diagnosis of pleural malignant neoplasia, and may help prioritize further diagnostic testing.

Spontaneous osteosarcoma in craniomaxillofacial fibrous dysplasia: clinical and computed tomographic features in 8 cases.

The aim of this study was to evaluate the patient demographic and computed tomography (CT) imaging findings of spontaneous osteosarcoma in craniomaxillofacial fibrous dysplasia. Ten cases of spontaneous osteosarcoma in craniomaxillofacial fibrous dysplasia diagnosed during 1993-2013 were reviewed. Eight cases with CT images were reviewed. The mean age of diagnosis of osteosarcoma was 37.8 years (range, 8-55 years). The presence of a soft tissue extension component beyond the area of cortical bone destruction was demonstrated radiographically in 7 out of 8 cases. Mineralization of tumor matrix was seen in 6 cases. Periosteal reaction was demonstrated in only 1 case; 1 out of 6 cases showed significant enhancement on postcontrast CT images. Nine patients had surgical resections of tumor. Seven of them died of tumor, with a mean survival time of 5.3 years. This study provides CT imaging features with clinical information of spontaneous osteosarcoma in craniomaxillofacial fibrous dysplasia.

Evaluation of the relationship between extremity soft tissue sarcomas and adjacent major vessels using contrast-enhanced multidetector CT and three-dimensional volume-rendered CT angiography: a preliminary study

Accurate description of the relationship between extremity soft tissue sarcoma and the adjacent major vessels is crucial for successful surgery. In addition to magnetic resonance imaging (MRI) or in patients who cannot undergo MRI, two-dimensional (2D) postcontrast computed tomography (CT) images and three-dimensional (3D) volume-rendered CT angiography may be valuable alternative imaging techniques for preoperative evaluation of extremity sarcomas. To preoperatively assess extremity sarcomas using multidetector CT (MDCT), with emphasis on postcontrast MDCT images and 3D volume-rendered MDCT angiography in evaluating the relationship between tumors and adjacent major vessels. MDCT examinations were performed on 13 patients with non-metastatic extremity sarcomas. Conventional CT images and 3D volume-rendered CT angiography were evaluated, with focus on the relationship between tumors and adjacent major vessels. Kappa consistency statistics were performed with surgery serving as the reference standard. The relationship between sarcomas and adjacent vessels was described as one of three patterns: proximity, adhesion, and encasement. Proximity was seen in five cases on postcontrast CT images or in eight cases on volume-rendered images. Adhesion was seen in three cases on both postcontrast CT images and volume-rendered images. Encasement was seen in five cases on postcontrast CT images or in two cases on volume-rendered images. Compared to surgical results, postcontrast CT images had 100% sensitivity, 83.3% specificity, 87.5% positive predictive value, 100% negative predictive value, and 92.3% accuracy in the detection of vascular invasion (κ = 0.843, P = 0.002). 3D volume-rendered CT angiography had 71.4% sensitivity, 100% specificity, 100% positive predictive value, 75% negative predictive value, and 84.6% accuracy in the detection of vascular invasion (κ = 0.698, P = 0.008). On volume-rendered images, all cases with adhesion or encasement had arterial stenosis and all tumors' feeding arteries were clearly depicted. 2D postcontrast CT images are superior to 3D volume-rendered CT angiography in evaluating the relationship between extremity sarcomas and adjacent major vessels. 3D volume-rendered CT angiography is good at assessing the tumor's blood supply, the longitudinal extent of vascular involvement, and the vascular narrowing due to the tumor.

Characteristic MR and CT imaging findings of hepatobiliary paragonimiasis and their pathologic correlations

Hepatobiliary paragonimiasis (HP) is not commonly encountered and may be confused with hepatobiliary tumors; however, computed tomography (CT) and magnetic resonance imaging (MRI) features of HP allow this entity to be distinguished from other diseases. To present the CT and MRI findings in patients with HP and to describe some specific imaging findings along with their pathological correlations. Imaging and clinical findings of 21 patients (9 boys/men and 12 girls/women; age range 3-67 years; mean age 40 years) who were diagnosed with HP were retrospectively evaluated. Among these patients, 16 underwent CT examination only, two had MR examination only, and three underwent both CT and MR. All patients underwent surgery, and the HP diagnosis was confirmed by the surgical and histopathologic results. Chronic abdominal pain or back pain was reported by 14 patients, severe abdominal pain with acute onset was reported by one patient, and six patients were asymptomatic and were discovered incidentally. Peripheral eosinophilia was present in 14 patients (14/21, 66.7%), and abnormal liver function tests were found in 16 patients (16/21, 76.2%). Of the 19 patients who underwent CT imaging, 17 patients showed multiple mixed hypodense lesions or multiple cysts with inlaying septation with separate irregular rims or circular enhancement on post-contrast CT images. Tunnel-shaped microabscesses and necrotic cavities were found in the lesions of 12 of those 17 patients. The other two patients showed smaller cystic masses. MRI showed faveolate T1 hypointense and T2 hyperintense areas in the liver parenchyma with rim or peripheral enhancement. Nodular or circular hyperintense materials were found scattered in the lesions on T1-weighted imaging. CT and MRI can reveal the radiological-pathological features of HP. Together with laboratory findings, MRI and CT findings may provide diagnostic clues, especially in endemic areas, that are very important for the selection of treatment methods.

Computed Tomography and Magnetic Resonance Features of Gliosarcoma

To investigate the features of pathologically confirmed gliosarcomas using computed tomography (CT) and magnetic resonance (MR) imaging. We retrospectively reviewed the cross-sectional CT and MR images of 54 patients (37 males and 17 females; mean age, 44.5 years; range, 13-74 years) with gliosarcomas confirmed by histopathology. Across all patients, there were 59 lesions. On nonenhanced CT and MR images, tumors were predominantly inhomogeneous. On the postcontrast CT and MR images, 50 (84.7%) irregular lesions had thick walls with a strong rim- and ringlike enhancement, whereas the remaining 9 (15.3%) round or oval lesions had even thin walls with an enhanced peripheral ring. Magnetic resonance spectroscopy showed increased choline and lactate values, along with decreased N-acetylaspartate and creatine values. On diffusion-weighted imaging, the tumor was slightly or markedly hyperintense compared with the white matter. A well-demarcated mass located peripherally, with rimlike or ring enhancement, is a common presentation of gliosarcoma on CT and MR images. In addition, magnetic resonance spectroscopy and diffusion-weighted imaging can be used to make a differential diagnosis.

Computed tomography and low-field magnetic resonance imaging of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism: 11 cases (2001–2003)

To compare the results of computed tomography (CT) and magnetic resonance imaging (MRI) of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism (PDH) caused by histologically confirmed pituitary adenoma. Retrospective case series. 11 dogs with PDH that underwent transsphenoidal hypophysectomy. Medical records of dogs examined between January 2001 and March 2003 were reviewed. Dogs were included in this study if they had clinical signs of hypercortisolism at the time of admission (for which PDH was diagnosed) and underwent transsphenoidal hypophysectomy. Pre- and postcontrast CT and low-field MRI (0.2-Tesla magnet) were performed on the same day as surgery for each dog. An abnormal pituitary gland was found in 7 dogs by use of MRI and in the same 7 dogs by use of CT. Significant differences were found between postcontrast CT and MR images for height, width, and length of the pituitary gland; brain area; and thickness of the sphenoid bone. However, the pituitary gland height-to-brain area ratio determined from postcontrast CT and MR images was not significantly different. The signal-to-noise ratio and contrast-to-noise ratio of pre- and postcontrast MR images were significantly higher than those of the CT images. Low-field MRI and dynamic CT imaging of the pituitary gland provided comparable information on the presence of pituitary adenomas in dogs with PDH.

Factors predictive of abnormal results for computed tomography of the head in horses affected by neurologic disorders: 57 cases (2001–2007)

To determine neurologic indications associated with abnormal results for computed tomography (CT) imaging of the head of horses affected by neurologic disorders. Retrospective case series. 57 horses. Signalment, history, clinical abnormalities, and clinicopathologic findings were obtained from medical records of horses examined because of neurologic disorders, and precontrast and postcontrast CT images of the head were reviewed. Data were analyzed by use of univariate and multivariate logistic regression. For a horse with abnormal mentation, odds of having abnormal results for CT imaging of the head was 30 times (95% confidence interval [CI], 2.36 to 374.63) the odds for a similar horse without abnormal mentation. For a horse with cranial nerve deficits, odds of having abnormal results for CT imaging of the head was 11 times (95% CI, 1.00 to 127.96) the odds for a similar horse without cranial nerve deficits. For a horse with seizure-like activity, odds of having abnormal results for CT imaging of the head was 0.05 times (95% CI, 0 to 0.90) the odds for a similar horse without seizures. These results suggested that alterations in consciousness and cranial nerve deficits were strong predictors of abnormal CT findings for the head of affected horses. Thus, CT can be a useful complementary diagnostic test in horses with these neurologic deficits. In contrast, alternative diagnostic tests (eg, electroencephalography and magnetic resonance imaging) should be considered in horses with seizure-like activity that do not have head trauma or cranial nerve deficits.

Liver lobe torsion in a Shih‐tzu dog

MADAM We write to report a case of liver lobe torsion (LLT) in a small breed dog where ultrasound and computed tomography (CT) were useful in diagnosis of the condition. A 3-year-old male shih-tzu was presented with abdominal pain and acute onset vomiting, followed by progressive weakness. On examination the abdomen was tense and a firm painful mass was palpated cranially. Haematology and biochemistry profiles showed elevated liver enzymes, mild anaemia, and mild thrombocytosis. Abdominal radiographs showed a triangular mass in the cranial abdomen to the left of midline and caudal to the liver displacing the small intestine and the left kidney caudally. An abdominal ultrasound revealed a small volume of anechoic peritoneal effusion and an enlarged, homogenous, and hypoechoic left liver lobe. No blood flow was seen in the vessels including the hepatic veins and the portal veins within this liver lobe. Four detector-row CT was performed without anaesthesia. Pre-contrast CT revealed enlargement and caudoventral deviation of the left liver lobe with an irregular surface. Hypodense free fluid was present in the peritoneum. Post-contrast images showed no change in density of the abdominal left liver but normal contrast enhancement was seen in the remainder of the hepatic parenchyma (Figs 1A and 1B). A dorsal-plane image showed fissures on the liver surface, supporting rupture of the liver (Fig 1C, arrows). A diagnosis of LLT was made based on the imaging findings. Pre-contrast (A) and post-contrast (B,C) CT images through the cranial abdomen reveal an enlargement of the left lateral (LL) and left medial (LM) liver lobe without contrast enhancement. On dorsal-plane image, there are fissures on the liver surface (arrows) After a transfusion of whole blood, an exploratory laparotomy was performed. At surgery, 180 degree torsion of the left medial and left lateral liver lobe was identified and haemorrhagic peritoneal effusion and parenchymal rupture were present. A lobectomy of the affected regions was performed. The patient awoke from the anaesthesia, but died six hours after surgery. The cause of death was suspected to be severe postoperative complications. Most previous reports of LLT in dogs occurred in large breeds (Swann and Brown 2001, Schwartz and others 2006) and a few medium-sized breeds including the beagle (Sonnenfield and others 2001). To the author’s knowledge, this is the first case reported in such a small breed dog. Furthermore, this is the first report of the use of CT in diagnosis of the condition. Multiplanar reconstructions are particularly useful in assessment of complex anatomical abnormalities such as lung lobe torsion, and in this case, LLT. Liver lobe torsion, though very rare, should be considered in the differential diagnosis for acute abdominal pain, even in small breed dogs.

CT‐GUIDED STEREOTACTIC BRAIN BIOPSY USING THE KOPF STEREOTACTIC SYSTEM

This report describes computed tomography (CT)-guided stereotactic brain biopsy using the Kopf stereotactic system, a commercially available patient restraint system which does not require additional modification for use in small animals. The accuracy of biopsy needle placement was determined by injecting dilute iohexol into cadaver brains and comparing the three-dimensional coordinates of the desired target location to the actual needle tract observed on postcontrast CT images. Overall mean error in needle placement in a dorsoventral trajectory was 0.9 +/- 0.9 mm (n = 80 injections) for dogs and 1.0 +/- 1.1 mm (n = 30 injections) for cats. The overall mean error in needle placement via an oblique trajectory in five dogs was 1.7 +/- 1.6 mm (n = 12 injections). These results suggest that this system can be used to successfully place a biopsy needle into the brain to obtain biopsies from small lesions.

Differentiation between cholesteatoma and inflammatory process of the middle ear, based on contrast-enhanced computed tomography imaging

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Differentiation between cholesteatoma and inflammatory process of the middle ear, based on contrast-enhanced computed tomography imaging

To assess the usefulness of delayed post-contrast computed tomography (CT) examination for the detection of residual or recurrent cholesteatoma after canal wall up tympanoplasty. This prospective, non-randomized study, set within an academic medical centre, included 17 consecutive patients who had undergone canal wall up tympanoplasty for cholesteatoma, with possible recurrence. Pre-contrast CT scans and delayed post-contrast images were compared with second look surgical findings. A residual or recurrent cholesteatoma was found in eight of the 17 patients at revision surgery and was correctly diagnosed on post-contrast CT images in six patients (75 per cent). In the two misdiagnosed cases, cholesteatoma pearls smaller than 2.5 mm were not seen on post-contrast CT. The sensitivity of the imaging test was 75 per cent, the specificity was 60.1 per cent, the positive predictive value was 88.1 per cent and the negative predictive value was 81.8 per cent. Computed tomography with delayed post-contrast images is a sensitive imaging modality for the detection of residual cholesteatoma. If proven reliable, this method of non-invasive imaging could spare the patient unnecessary revision surgery.