Use of computed tomography sinography for evaluation of draining tracts in 27 dogs and one cat.

OBJECTIVES: To describe the clinical findings, imaging findings and outcome in patients in which CT sinography was performed, and assess to what degree this technique adds information about the extent of a tract or increases the accuracy of diagnosis of foreign bodies on CT. MATERIALS AND METHODS: Retrospective review of medical records of 27 dogs and one cat with draining tracts that had CT sinography. Pre- and post-intravenous (IV) contrast CT series were compared with CT sinography in each patient. RESULTS: Median duration of clinical signs before referral was 85 days (range 2 to 1478 days). The most common reported clinical signs were swelling (14/28, 50%) and regional pain (5/28, 18%). CT sinography revealed a more extensive tract than post-IV contrast CT in 21% cases. On post-IV contrast CT, 31% of foreign bodies were detected compared to 23% on CT sinography. All four foreign bodies detected by CT were observed in the non-contrast images. Surgery was performed after CT in 22 (79%) cases. Thirteen (46%) draining tracts resolved after surgery, three (11%) resolved without surgery, six (21%) persisted or recurred after surgery, and six (21%) were lost to follow-up. CLINICAL SIGNIFICANCE: CT sinography provides limited additional information about the extent of draining tracts compared to pre- and post-IV contrast CT images and did not increase the number of foreign bodies identified.

Histiocytic sarcoma in miniature schnauzers: 30 cases.

OBJECTIVES: To summarise the clinical presentation and outcomes in a series of miniature schnauzers diagnosed with histiocytic sarcoma. MATERIALS AND METHODS: Retrospective review of medical records of miniature schnauzers diagnosed with histiocytic sarcoma between 2008 and 2019 at two referral centres in the UK. Signalment, clinical signs at initial presentation, imaging results and clinico- and histopathological findings, treatment type and outcome were recorded. Progression-free survival and overall survival time were calculated. RESULTS: Thirty dogs were included. Twenty-four of 29 dogs undergoing imaging of the thorax had lung and/or mediastinal involvement. The median overall survival time for dogs that were not euthanased within 3 days of diagnosis was 117 days (range 10 to 790). Three dogs underwent surgery; 13 received treatment with lomustine as a sole therapy - with partial responses documented on imaging in five of six dogs and 11 of 13 showing clinical improvement. CLINICAL SIGNIFICANCE: Histiocytic sarcoma should be considered as a differential diagnosis for miniature schnauzers with pulmonary masses. Although responses to treatment were common, they were usually short-lived because of the aggressive nature of the disease.

Diagnostic imaging observations in cats treated with the subcutaneous ureteral bypass system.

OBJECTIVES: To describe pre- and post-operative ultrasonographic and fluoroscopic findings, including any abnormalities, in cats treated for ureteral obstruction with a subcutaneous ureteral bypass system. METHODS: Retrospective review of imaging findings in cats with ureteral obstruction that had surgery to place the first version of the bypass system and at least one follow-up ultrasound or fluoroscopic study. Pre- and post-operative renal pelvic diameter on ultrasound, fluoroscopic appearance of the bypass system and any related abnormality were recorded. RESULTS: Eighty-one cats were included (47 unilateral, 34 bilateral bypass systems). Median preoperative renal pelvic diameter was 9 mm (range 3 to 28 mm) and median renal pelvic diameter at the first postoperative ultrasound was 3 mm (range 2 to 23 mm). The median number of postoperative imaging studies was two (range 1 to 8) and the median follow-up period after surgery was 205 days (range 1 to 1378 days). Bypass system abnormalities were identified postoperatively in 43 (53%) cats, including nephrostomy or cystostomy catheter blockage due to an undetermined cause or kinking of the catheter, nephrostomy or cystostomy catheter leakage, non-obstructive kinking of the catheter and loose nephrostomy pig-tail loop. Many abnormalities required repeat surgery, but others were managed conservatively. Fifty-four percent of obstructed ureters became patent after bypass placement, although the majority remained slightly dilated or had irregular margins compatible with chronic inflammation. CLINICAL SIGNIFICANCE: Bypass abnormalities, mainly tube blockage, occurred frequently in cats treated for ureteral obstruction. Ultrasonography and fluoroscopy were useful for postoperative examination, including documenting renewed ureteral patency and investigation of suspected abnormalities.

Determining the anatomical origin of canine hepatic masses by CT.

OBJECTIVES: To identify CT features of canine hepatic masses that could be used to determine their divisional or lobar origin. MATERIALS AND METHODS: Preoperative, postcontrast CT images of 57 surgically resected hepatic masses were reviewed with respect to their size, position relative to the midline, gallbladder and portal vein, nearest recognisable hepatic lobar vein or portal vein and point of contact with the diaphragm and displacement of adjacent organs. RESULTS: The most prevalent histological diagnoses were hepatocellular carcinoma (n=26; 46%) and adenoma (n=10; 18%). Based on surgical assessment, it was observed that masses originated in the left hepatic division in 30 (53%) instances, central division in seven (12%) and right division in 20 (35%). All masses to the left of midline were left divisional, but only 18/30 (60%) masses to the right of midline were right divisional. Most (26/31; 84%) masses to the left of the gallbladder were left divisional and 84% (16/19) masses to the right of the gallbladder were right divisional. Half (10/20; 50%) of the right-divisional masses were medial, lateral or dorsal to the portal vein, but all other hepatic masses were ventral to the portal vein. A hepatic lobar vein or portal vein branch adjacent to the mass was observed in 53 (93%) instances; this feature correlated with surgical assessment of the affected division in 53 (93%) hepatic masses and the affected lobe in 32 (56%). CLINICAL SIGNIFICANCE: Combining CT features of hepatic masses appears to be an accurate method for determining their divisional or lobar origin.

CT findings in Pneumocystis carinii pneumonia in five dogs.

Pneumocystis carinii pneumonia is a rare disease in dogs. It is primarily reported in cavalier King Charles spaniels and miniature dachshunds with suspected underlying immunodeficiency. This case series reports the findings in five dogs (four cavalier King Charles spaniels and one Bedlington terrier) with confirmed P. carinii pneumonia. Thoracic (CT) revealed ground glass opacity of the pulmonary parenchyma with a diffuse or multifocal distribution. The severity of this pattern was variable. Less consistent imaging findings included parenchymal bands, bronchial dilation and signs consistent with pulmonary hypertension. Four dogs recovered well with treatment and there was resolution of CT abnormalities in all dogs with follow-up.

How useful is abdominal ultrasonography in dogs with diarrhoea?

OBJECTIVE: To assess the utility of abdominal ultrasonography in the diagnostic work-up of dogs with diarrhoea. METHODS: Retrospective cross-sectional study based on a referral population of dogs with diarrhoea. Associations between the clinical signs, use of abdominal ultrasonography, results of abdominal ultrasonography and subsequent work-up were examined. The utility of abdominal ultrasonography was scored as high, moderate, none or counterproductive based on review of medical records. RESULTS: Medical records of 269 dogs were reviewed, of which 149 (55%) had abdominal ultrasonography. The most frequent result was no ultrasonographic abnormalities affecting the intestine in 65 (44%) dogs. Ultrasonography results were associated with subsequent work-up as follows: (1) no detected abnormalities and dietary trial; (2) focal thickening of the intestinal wall, loss of intestinal wall layers or enlarged abdominal lymph nodes and ultrasound-guided fine-needle aspirates; (3) diffuse thickening of the intestinal wall or hyperechoic striations in the small intestinal mucosa and endoscopy; and (4) small intestinal foreign body and coeliotomy. Abdominal ultrasonography was considered to be diagnostic without further testing in only four (3%) dogs: two had a portosystemic shunt identified ultrasonographically, one had a linear foreign body and one had a perforated pyloric ulcer. Abdominal ultrasonography had moderate utility in 56 (38%) dogs and no utility in 79 (53%) dogs. Abdominal ultrasonography was considered counterproductive in 10 (7%) dogs because results were either falsely negative or falsely positive. CLINICAL SIGNIFICANCE: These results should prompt clinicians to reconsider routine use of abdominal ultrasonography in dogs with diarrhoea.

Clinical findings and results of diagnostic imaging in 82 dogs with gastrointestinal ulceration.

OBJECTIVES: To describe clinical and imaging findings in dogs with confirmed gastrointestinal ulceration, to compare findings in dogs with perforated and non-perforated ulcers and to estimate the sensitivities of radiography, ultrasonography and computed tomography (CT) for gastrointestinal ulceration and perforation. METHODS: Retrospective review of medical records of 82 dogs that had a macroscopic ulcer in the gastric or intestinal mucosa diagnosed directly at endoscopy, surgery or necropsy and had survey radiography, ultrasonography or a CT scan of the abdomen during the same period of hospitalisation. RESULTS: The most frequent clinical signs were vomiting in 88% dogs, haematemesis in 32%, melaena in 31% and weight loss in 7%. The most frequent imaging findings in dogs with non-perforated ulcers were gastrointestinal mural lesion in 56%, mucosal defect compatible with an ulcer in 44% and peritoneal fluid in 21%. In dogs with perforated ulcers the most frequent imaging findings were peritoneal fluid in 83%, gastrointestinal mural lesion in 48%, peritoneal gas in 31% and mucosal defect compatible with an ulcer in 29%. Sensitivities of radiography, ultrasonography and CT were 30, 65 and 67% in dogs with non-perforated ulcers and 79, 86 and 93% in dogs with perforated ulcers, respectively. CLINICAL SIGNIFICANCE: In dogs with non-perforated ulcers, survey radiography was usually negative whereas ultrasonography and CT frequently enabled detection of the site of the ulcer; in dogs with perforated ulcers, radiography was frequently positive for peritoneal gas and CT was a sensitive modality for both the ulcer and signs of perforation.

Associations between respiratory signs and abnormalities reported in thoracic CT scans of cats.

OBJECTIVES: To estimate the prevalence of subclinical abnormalities reported in thoracic (CT) scans of cats and to investigate associations between respiratory signs and CT signs. METHODS: Retrospective review of signalment, indications, respiratory signs and reported CT findings in a series of cats. Associations between patient variables, respiratory signs and CT signs were analysed using multi-variable regression methods. RESULTS: Records of 352 consecutive cats were reviewed. Abnormalities affecting thoracic structures were reported in CT scans of 138/179 (77%) cats that did not have respiratory signs; the most prevalent CT findings were pulmonary collapse (41%), evidence of bronchial disease (24%) and space-occupying lesions (21%). Dyspnoea, cough and tachypnoea were associated with space-occupying lesions. Dyspnoea was also associated with pulmonary consolidation and atelectasis. Increasing body weight was associated with pulmonary atelectasis and increasing age was associated with evidence of bronchial disease. CLINICAL SIGNIFICANCE: Abnormalities were commonly detected in thoracic CT scans of cats that did not show respiratory signs. The most prevalent abnormality - pulmonary atelectasis - is probably a temporary effect of sedation or anaesthesia. A high prevalence of subclinical abnormalities and limited correlations between clinical signs and CT findings will complicate diagnosis.

Assessment of mitral regurgitation in dogs: comparison of results of echocardiography with magnetic resonance imaging.

OBJECTIVES: Echocardiography is used routinely to assess mitral regurgitation severity, but echocardiographic measures of mitral regurgitation in dogs have not been compared with other quantitative methods. The study aim was to compare echocardiographic measures of mitral regurgitation with cardiac magnetic resonance imaging-derived mitral regurgitant fraction in small-breed dogs. METHODS: Dogs with myxomatous mitral valve disease scheduled for magnetic resonance imaging assessment of neurological disease were recruited. Correlations were tested between cardiac magnetic resonance imaging-derived mitral regurgitant fraction and the following echocardiographic measures: vena contracta/aortic diameter, transmitral E-wave velocity, amplitude of mitral prolapse/aortic diameter, diastolic left ventricular diameter:aortic diameter, left atrium:aortic diameter, mitral regurgitation jet area ratio and regurgitant fraction calculated using the proximal isovelocity surface area method. RESULTS: Measurement of cardiac magnetic resonance imaging-derived mitral regurgitant fraction was attempted in 21 dogs. Twelve consecutive, complete studies were obtained and 10 dogs were included in the final analysis: vena contracta/aortic diameter (r = 0 · 89, p = 0 · 001) and E-wave velocity (r = 0 · 86, p = 0 · 001) had the strongest correlations with cardiac magnetic resonance imaging-derived mitral regurgitant fraction. E velocity had superior repeatability and could be measured in all dogs. The presence of multiple jets precluded vena contracta/aortic diameter measurement in one dog. CLINICAL SIGNIFICANCE: Measurement of cardiac magnetic resonance imaging-derived mitral regurgitant fraction is feasible but technically demanding. The echocardiographic measures that correlated most closely with cardiac magnetic resonance imaging-derived mitral regurgitant fraction were vena contracta/aortic diameter and E-wave velocity.

Acceptance rates for manuscripts submitted to veterinary peer-reviewed journals in 2012.

REASONS FOR PERFORMING STUDY: Relatively few journals publish their annual acceptance rate, although this figure is of scientific and academic interest. OBJECTIVES: To determine the acceptance rate for manuscripts submitted to veterinary peer-reviewed journals during 2012 and to determine the proportions of submitted manuscripts that were accepted without revision, accepted after revision or rejected. STUDY DESIGN: Self-reporting email questionnaire METHODS: Editors of 118 peer-reviewed journals listed in the Web of Science in the subject category veterinary sciences were invited by email to submit data pertinent to manuscripts submitted to their journal in 2012. RESULTS: Data were received from 30 (26%) journals. Mean ± s.d. acceptance rate was 47 ± 15%. On average 3 ± 5% submitted manuscripts were accepted without revision, 44% ± 15% manuscripts were accepted after revision, 4 ± 4% manuscripts were withdrawn by authors, 46 ± 17% manuscripts were rejected and 3 ± 5% manuscripts were still pending at the end of the study period. CONCLUSIONS: With so few manuscripts accepted without revision, prospective authors must expect to expend time and effort revising and resubmitting their manuscripts for publication. Although authors are frequently able to correct manuscript flaws identified by reviewers, the knowledge that less than half submitted manuscripts are accepted might help stimulate prospective authors to try to submit better quality manuscripts.

Computed tomographic findings in 44 dogs and 10 cats with grass seed foreign bodies.

OBJECTIVE: To supplement recent reports of computed tomographic (CT) findings in dogs and cats with grass seed foreign bodies. METHODS: Retrospective review of cases that had CT scan and subsequent retrieval of a grass seed during the same period of hospitalisation from a site included in the scan. RESULTS: Records of 44 dogs and 10 cats were reviewed. Most were presented in the months July to December. Median duration of clinical signs was 4 weeks (range 2 days to 2 years). The most frequent clinical signs were soft tissue swelling (30% cases), coughing (28%), sneezing (28%) and discharge (26%). Grass seeds were retrieved from the thorax (35% cases), nasal cavity (31%), ear (7%), other sites in the head and neck (22%), sublumbar muscles (2%) and pelvic limb (2%). The grass seed was visible in CT images in 10 (19%) cases. Secondary lesions were visible in CT images of 52 (96%) cases, including collection of exudate (37%), abscess (24%), enlarged lymph nodes (22%) and pulmonary consolidation (20%). CT images appeared normal in 4% animals. CLINICAL SIGNIFICANCE: Grass seeds within the respiratory tract are frequently visible in CT images, but in general CT appears to be more useful for localisation of secondary lesions than as a method of definite diagnosis.

Magnetic resonance imaging for detection of late meniscal tears in dogs following tibial tuberosity advancement for treatment of cranial cruciate ligament injury.

OBJECTIVES: To document the use of and to estimate the accuracy of magnetic resonance (MR) imaging for detection of late meniscal tears in dogs with cranial cruciate ligament injury treated with tibial tuberosity advancement (TTA). METHODS: Medical records of dogs that had TTA followed by stifle MR imaging for suspected meniscal tear and subsequent arthrotomy were reviewed retrospectively. Magnetic resonance images were reviewed independently by an observer blinded to clinical information who classified menisci as torn, abnormal but intact, or normal. Magnetic resonance and surgical findings were compared. RESULTS: Eight stifles from large breed dogs were included. Six stifles had a medial meniscal tear identified in MR images and later confirmed surgically. In the remaining two stifles, the menisci appeared intact in MR images and no tear was identified at subsequent arthrotomy. Lateral menisci in all stifles appeared intact in MR images and were considered normal at surgery. Susceptibility artefacts associated with TTA implants were present in all images but did not adversely affect interpretation of intra-articular structures. CLINICAL SIGNIFICANCE: Magnetic resonance imaging appears to be accurate for diagnosis of late meniscal tears. Artefacts associated with TTA implants did not prevent evaluation of critical intra-articular structures. Further investigation with MR imaging should be considered when late meniscal tear is suspected following TTA.

Pulmonary lipoma in a dog.

An eight-year-old, neutered, male German short-haired pointer was presented for a chronic cough and an intrathoracic mass. Computed tomography revealed a mass with low attenuation in the right caudal lung lobe that invaded the principal bronchi. The mass was removed by right caudal and accessory lung lobectomy. The histopathological diagnosis was pulmonary lipoma. The clinical signs resolved following surgery. There was no evidence of recurrence or de novo lesions on computed tomography performed 12 months post-surgery. To the authors' knowledge, this is the first report of a pulmonary lipoma in a dog.

Canine meningeal disease: associations between magnetic resonance imaging signs and histologic findings.

In order to compare the accuracy of MR sequences for diagnosis of meningeal disease, MR images of the brain, and histopathologic specimens including the meninges of 60 dogs were reviewed retrospectively by independent observers in a cross-sectional study. MR images included T1-weighted pre- and postgadolinium images, subtraction images, T2-weighted images, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images. Pathologic changes affected the pachymeninges in 16 dogs, leptomeninges in 35 dogs, and brain in 38 dogs. The meninges were normal in 12 dogs. Meninges were classified histopathologically as normal (grade 0), slightly or inconsistently affected (grade 1), or markedly affected (grade 2). When applying relaxed pathologic criteria (grades 0 and 1 considered normal), the results of ROC analysis (area under curve, AUC) were: T1-weighted postcontrast images 0.74; subtraction images 0.7; T2-weighted images 0.68; FLAIR images 0.56. The difference in AUC between T1-weighted postgadolinium images and FLAIR images was significant (P = 0.04). AUC for FLAIR images was not significantly different from 0.5. When applying strict pathologic criteria (only grade 0 considered normal), none of the MR sequences had AUC significantly different from 0.5. On the basis of T1-weighted postgadolinium images and subtraction images, correct anatomic classification of lesions occurred more often for pachymeningeal than leptomeningeal lesions (P < 0.001). Overall, MR imaging had low sensitivity for diagnosis of meningeal pathology in dogs, particularly for changes affecting the leptomeninges. Subtraction images had similar accuracy to T1-weighted postgadolinium images for meningeal lesions in dogs. T2-weighted FLAIR images appear to have limited diagnostic utility for meningeal lesions.

Lack of associations between ultrasonographic appearance of parenchymal lesions of the canine liver and histological diagnosis.

OBJECTIVE: To assess if there are any ultrasonographic features that may enable tentative diagnosis of hepatic parenchymal disease. METHODS: Records of 371 dogs that had abdominal ultrasonography and abnormal liver on biopsy or necropsy were reviewed. RESULTS: Histological diagnoses were hepatitis (n=77), nodular hyperplasia (n=47), vacuolar change (n=45), fibrosis (n=32), primary hepatic carcinoma (n=30), lymphoma (n=28), metastatic neoplasia (n=27), necrosis (n=21), lipidosis (n=17), haemangiosarcoma (n=13), round cell tumour (n=9), hepatocellular adenoma (n=8), degenerative change (n=6), steroid hepatopathy (n=7) and extramedullary haematopoiesis (n=4). The most prevalent ultrasonographic features were multifocal lesions (63% livers with haemangiosarcoma and 43% livers with hepatocellular carcinoma), diffuse lesions (71% livers with steroid hepatopathy, 44% livers with fibrosis and 40% livers with vacuolar hepatopathy), hyperechoic lesions (71% livers with steroid hepatopathy, 41% livers with lipidosis and 38% livers with fibrosis), heterogeneous lesions (62% livers with haemangiosarcoma), hepatomegaly (43% livers with steroid hepatopathy) and peritoneal fluid (62% livers with haemangiosarcoma). Target lesions were associated with malignancy in 67% instances. Marked variability in ultrasonographic appearance of lesions was observed for all diagnoses, and no statistically significant associations between ultrasonographic appearance and diagnosis were found. CLINICAL SIGNIFICANCE: Histological examination remains essential for diagnosis of canine hepatic disease.

Reducing susceptibility artefacts in magnetic resonance images of the canine stifle following surgery for cranial cruciate ligament deficiency.

BACKGROUND: Magnetic resonance (MR) images of the postoperative canine stifle are adversely affected by susceptibility artefacts associated with metallic implants. OBJECTIVES: To determine empirically to what extent susceptibility artefacts could be reduced by modifications to MR technique. METHODS: Three cadaveric limbs with a tibial plateau levelling osteotomy (TPLO), tibial tuberosity advancement (TTA), or extra-capsular stabilization (ECS) implant, respectively, were imaged at 1.5T. Series of proton density and T2-weighted images were acquired with different combinations of frequency-encoding gradient (FEG) direction and polarity, stifle flexion or extension, echo spacing (ES), and readout bandwidth (ROBW), and ranked. The highest rank (a rank of 1) corresponded to the smallest artefact. RESULTS: Image ranking was affected by FEG polarity (p = 0.005), stifle flexion (p = 0.01), and ROBW (p = 0.0001). For TPLO and TTA implants, the highest ranked images were obtained with the stifle flexed, lateromedial FEG, and medial polarity for dorsal images, and craniocaudal FEG and caudal polarity for sagittal images. For the ECS implant, the highest ranked images were obtained with the stifle extended, a proximodistal FEG and proximal polarity for dorsal images, and craniocaudal FEG and cranial polarity for sagittal images. CLINICAL SIGNIFICANCE: Susceptibility artefacts in MR images of postoperative canine stifles do not preclude clinical evaluation of joints with ECS or TTA implants.

Effects of surgical implants on high-field magnetic resonance images of the normal canine stifle.

To determine the effect of surgical implants on the depiction of canine stifle anatomy in magnetic resonance (MR) images, three canine cadaver limbs were imaged at 1.5 T before and after tibial plateau leveling osteotomy (TPLO), tibial tuberosity advancement (TTA), and extra-capsular stabilization (ECS), respectively. Susceptibility artifacts associated with implants were identified in MR images as a signal void and/or signal misregistration, which obscured or distorted the anatomy. Using the preoperative images as a reference, articular structures of the stifle in postoperative images were graded using an ordinal scale to describe to what degree each anatomic structure could be evaluated for clinical purposes. The TPLO implant, which contains ferromagnetic stainless steel, produced marked susceptibility artifacts that obscured or distorted most stifle anatomy. The titanium alloy TTA implants and the stainless steel crimps used for ECS produced susceptibility artifacts that mainly affected the lateral aspect of the stifle, but allowed the cruciate ligaments and medial meniscus to be evaluated satisfactorily. Susceptibility artifact was significantly less marked in images obtained using turbo spin-echo (TSE) sequences than in sequences employing spectral fat saturation. Clinical MR imaging of canine stifles containing certain metallic implants is feasible using TSE sequences without fat saturation.

Canine intracranial neoplasia: clinical risk factors for development of epileptic seizures.

OBJECTIVES: To identify clinical risk factors for seizures in dogs with intracranial neoplasia. METHODS: A cross-sectional retrospective study of 68 dogs with histopathologically confirmed primary or secondary intracranial neoplasia, complete clinical history and magnetic resonance imaging of the brain was conducted. Signalment and clinical history were retrieved from clinical records and magnetic resonance images of the brain were re-evaluated. Prevalence of findings was compared between dogs with and without seizures. RESULTS: Forty-two dogs had tumour-related seizures, the remaining 26 were seizure-free. Tumour types included meningioma (23 dogs with and 5 without seizures), glioma (9 dogs with and 6 without seizures), choroid plexus tumour (2 dogs without seizures), neuroblastoma (1 dog with seizures) and metastatic/invasive tumours including lymphoma (9 dogs with and 13 without seizures). On the basis of multi-variable logistic regression analysis, risk factors for seizures associated with intracranial neoplasia were magnetic resonance imaging findings consistent with the presence of neoplastic tissue in frontal lobe [odds ratio (OR) 9·61; 95% confidence interval (CI) 2·59 to 35·61], marked gadolinium enhancement (OR 10·41; 95% CI 2·07 to 52·30) and magnetic resonance imaging findings of subfalcine and/or subtentorial herniation (OR 3·88; 95% CI 1·10 to 13·71). CLINICAL SIGNIFICANCE: Dogs with primary or secondary intracranial neoplasia are at risk of seizures, particularly those with tumours that affect the frontal lobe, enhance markedly with gadolinium, or cause subfalcine and/or subtentorial herniation.