Comparative anatomy of dissected optic lobes, optic ventricles, midbrain tectum, collicular ventricles, and aqueduct: evolutionary modifications as potential explanation for non-tumoral aqueductal anomalies in humans.

PURPOSE: An extensive literature has postulated multiple etiologies for aqueductal stenosis. No publications were found, discussing that evolutionary modifications might explain aqueductal anomalies. This study's objectives were to review the evolutionary modifications of vertebrates' tectum structures that might explain human aqueduct anomalies. Undertaking vertebrate comparative study is currently not feasible in view of limitations in obtaining vertebrate material. Thus, vertebrate material collected, injected, dissected, and radiographed in the early 1970s was analyzed, focusing on the aqueduct and components of the midbrain tectum. METHODS: Photographs of brain dissections and radiographs of the cerebral ventricles and arteries of adult shark, frog, iguana, rabbit, cat, dog, and primate specimens, containing a barium-gelatin radiopaque compound, were analyzed focusing on the aqueduct, the optic ventricles, the quadrigeminal plate, and collicular ventricles. The anatomic information provided by the dissections and radiographs is not reproducible by any other radiopaque contrast currently available. RESULTS: Dissected and radiographed cerebral ventricular and arterial systems of the vertebrates demonstrated midbrain tectum changes, including relative size modifications of the mammalian components of the tectum, simultaneously with the enlargement of the occipital lobe. There is a transformation of pre-mammalian optic ventricles to what appear to be collicular ventricles in mammals, as the aqueduct and collicular ventricle form a continuous cavity. CONCLUSIONS: The mammalian tectum undergoes an evolutionary cephalization process consisting of relative size changes of the midbrain tectum structures. This is associated with enlargement of the occipital lobe, as part of overall neocortical expansion. Potentially, aqueductal anomalies could be explained by evolutionary modifications.

Increased number of subcortical hyperintensities on MRI in children and adolescents with Tourette's syndrome, obsessive-compulsive disorder, and attention deficit hyperactivity disorder.

OBJECTIVE: To investigate whether cerebral hyperintensities on T2-weighted magnetic resonance images (MRI) are associated with childhood neuropsychiatric disorders. METHOD: The authors compared the frequency of cortical and subcortical cerebral hyperintensities in 100 children and adolescents with Tourette's syndrome, obsessive-compulsive disorder (OCD), or attention deficit hyperactivity disorder (ADHD) and 32 healthy comparison subjects. RESULTS: The frequency of cerebral hyperintensities was significantly higher in subjects with Tourette's syndrome, OCD, or ADHD than in healthy comparison subjects; each diagnostic group seemed to contribute to this effect. Among the patient groups, the likelihood of detecting cerebral hyperintensities in the subcortex (primarily the basal ganglia and thalamus) was significantly greater than in the cortex. CONCLUSIONS: A childhood diagnosis of Tourette's syndrome, OCD, or ADHD significantly increased the likelihood of detecting cerebral hyperintensities, particularly in the subcortex, supporting the notion that subcortical injury may play a role in the pathophysiology of these conditions.

Clinical yield of computed tomography brain scans in older general medical patients.

OBJECTIVES: To evaluate the clinical yield of computed tomography (CT) brain scans in a prospective cohort of older patients admitted to the general medicine service. DESIGN: Nested cohort study of 117 subjects enrolled in previous prospective cohort study of 919 subjects. SETTING: University-affiliated teaching hospital. PARTICIPANTS: Hospitalized general medical patients aged 70 and older who received one or more brain CT scans during their hospital stay. MEASUREMENTS: Review of medical records and interpretation of the first brain CT scan in these 117 patients for indications for ordering scans and clinically significant brain abnormalities. Medical records of patients with brain CT scans with abnormalities were reviewed for 2 weeks after the scan for changes in medical management resulting from scan findings. Three independent reviewers adjudicated the presence of abnormalities and resulting treatment changes. RESULTS: Of the 117 brain CT scans, 32 (27%) were ordered to exclude intracranial hemorrhage, 30 (26%) to exclude cerebrovascular accident (CVA), 16 (14%) for falls, 15 (13%) for syncope, seven (6%) to exclude subdural hemorrhage, five (4%) for mental status change, and 12 (10%) for other reasons. Of the 117 brain CT scans, 29 (25%) had abnormalities, including acute CVA or hemorrhage, old CVA, meningioma, and other abnormalities. Only 10 (9% of all scans, 34% of abnormal scans) resulted in treatment changes (including consultations, further imaging, stroke evaluation, and drug changes). The presence of focal neurological deficits was significantly associated with treatment changes after CT scans (odds ratio=13.2, 95% confidence interval=1.7-161.5). CONCLUSION: These results suggest that the overall clinical yield of brain CT scans in unselected older hospitalized patients is low. Targeting scans toward patients with new focal neurological deficits will help to improve clinical yield.

Liver involvement in hereditary hemorrhagic telangiectasia: CT and clinical findings do not correlate in symptomatic patients.

OBJECTIVE: The purpose of our study was to report the multiphasic CT findings in patients with symptomatic liver involvement by hereditary hemorrhagic telangiectasia (HHT) and to correlate the CT findings with the type of clinical presentation. CONCLUSION: Patients with symptomatic HHT liver disease have diffuse hepatic telangiectases, a dilated common hepatic artery, and a high incidence of biliary abnormalities. Multiphasic CT is useful in diagnosing liver involvement due to HHT; however, no strong correlation was seen between CT findings and the clinical subtype of HHT liver disease.

Radiation dose associated with unenhanced CT for suspected renal colic: impact of repetitive studies.

OBJECTIVE: The purpose of our study was to assess the dose of ionizing radiation delivered through the use of unenhanced CT for suspected renal colic by determining the incidence of repeated unenhanced CT examinations and the cumulative radiation dose delivered. MATERIALS AND METHODS: All unenhanced CT examinations for suspected renal colic performed at our institution over a 6-year period were included, and patient age, sex, and multiplicity of examinations were determined. For the adult patient, this protocol prescribes a fixed tube current of 200 mA, 140 kVp, and a nominal slice width of 5 mm. The dose-length product (DLP) was estimated for 15 randomly chosen single-detector CT (SDCT) and MDCT adult flank pain examinations using manufacturer's software. The mean DLPs for SDCT and MDCT were computed and converted to effective doses. Total effective doses were calculated for patients who underwent more than three examinations, and values were compared with established standards. RESULTS: A total of 5,564 examinations were performed on 4,562 patients. Of these patients, 2,795 (61%) were women (mean age, 45.5 +/- 16.2 [SD] years) and 1,731 (38%) were men (mean age, 44.7 +/- 16.4 years), with 144 patients (3%) of pediatric age. The mean effective doses for a single study were 6.5 mSv for SDCT and 8.5 mSv for MDCT. A subset of 176 patients (4%) had three or more examinations, with estimated effective doses ranging from 19.5 to 153.7 mSv. All patients with multiple examinations had a known history of nephrolithiasis. CONCLUSION: Patients with a history of nephrolithiasis and flank pain are at increased risk for serial CT with potentially high cumulative effective doses.

Clinical and anatomic outcomes after embolotherapy of pulmonary arteriovenous malformations.

PURPOSE: To assess long-term clinical and imaging results of technically successful pulmonary arteriovenous malformation (AVM) embolization. MATERIALS AND METHODS: One hundred fifty-five patients with pulmonary AVMs underwent embolization during a period of 3 years. Recommended follow-up included clinical assessment, helical computed tomography, and physiologic evaluation within 1 year and then every 5 years. RESULTS: Hereditary hemorrhagic telangiectasia was present in 148 patients (95%). Four hundred fifteen pulmonary AVMs were occluded during 205 procedures. Clinical follow-up was available in all patients over 3-7 years and imaging follow-up was available in 144 patients (393 lesions) over 1-7 years (mean, 2.9 y). Problems related to pulmonary AVMs occurred in 35 patients (23%) at 42 time points: 22 patients with 23 symptomatic events and 17 patients with 19 asymptomatic events. Symptoms resulted from growth of nonembolized pulmonary AVMs (n = 19), residual embolized pulmonary AVMs (n = 5), or both (n = 2). Symptoms consisted of respiratory manifestations (n = 13), cerebral ischemia (n = 4), brain abscess (n = 5), hemoptysis (n = 3), and seizure (n = 1). Imaging showed pulmonary AVM involution in 97% of embolized lesions and 11 residual lesions (2.8%) in 10 patients (6.9%). These were caused by recanalization (n = 7), presence of an accessory feeding artery (n = 1), pulmonary collateral vessels (n = 1), and bronchial collateral vessels (n = 2). CT detected 10 of the 11 residual lesions. Imaging detected 97 previously small pulmonary AVMs that had enlarged to a significant size in 28 patients (18%), 15 of whom were symptomatic and 13 of whom were asymptomatic. CONCLUSIONS: Clinical and anatomic evaluation after pulmonary AVM embolization is important to detect persistent or reperfused lesions and enlarging lesions, with the latter more common. Patients with persistent, reperfused, or enlarging lesions often have symptoms, but a significant minority of patients are asymptomatic. More frequent assessment may improve detection before the onset of symptoms.

Chest radiograph as a triage tool in the imaging-based diagnosis of pulmonary embolism.

OBJECTIVE: The purpose of this study was to evaluate whether using a chest radiograph to triage patients being imaged for pulmonary embolism (PE) with pulmonary CT angiography (CTA) or ventilation-perfusion scintigraphy resulted in fewer indeterminate imaging results. CONCLUSION: Chest radiograph can be a valuable triage tool in deciding an appropriate technique for imaging PE, and can yield more definitive diagnoses.

Vein of Galen technique for occluding the aneurysmal sac of pulmonary arteriovenous malformations.

In seven of 255 consecutive patients (2.7%) who underwent pulmonary arteriovenous malformation (PAVM) embolization at our center between July 1, 1996, and July 1, 2000, the feeding artery was considered too short for safe occlusion with use of standard stainless-steel coils or detachable balloons. These patients were successfully treated with use of a modified vein of Galen technique similar to the one used for managing intracranial vein of Galen aneurysms. In this article, the authors report their experience with this technique in safely occluding the aneurysmal sacs of PAVMs in patients with short (<2 cm) feeding pulmonary arteries.