Computed tomography of the large bowel wall. Choice of slice thickness and intraluminal contrast medium.

RATIONALE AND OBJECTIVES: To determine the relative contribution of slice thickness and intraluminal contrast density to imaging of the large bowel wall. METHODS: The authors used phantom experiments to evaluate the partial volume averaging of 2-, 4-, and 8-mm slices on imaging a single density interface (320/-100 HU) and 5 dual-density interfaces (320/50/-100 HU, 160/50/-100 HU, 0/50/-100 HU, -100/50/100 HU, and -1000/50/100 HU). For the experiments with a dual-density interface, which simulated the bowel wall, the phantom was scanned at an angle 45 degrees to the scan plane. RESULTS: The most accurate display of interfaces was obtained with a slice thickness of 2 mm. When using 8-mm slices, walls can appear to be much thinner or thicker than normal or not even recognizable as a wall depending on the densities in the interface. Adjusting the density of the intraluminal contrast medium to within the range of the mean and window setting will improve the representation of the bowel wall. CONCLUSIONS: Slice thickness has a significant influence on the true representation of the bowel wall using computed tomography. This effect is greater than the effect of the intraluminal contrast medium density.

Role of MRI scanning in the diagnosis of cerebral visual disturbance.

Visual dysfunction as part of cerebral palsy may be due to lesions of the retrochiasmatic visual pathways. Cranial computed tomography can reveal conspicuous and characteristic abnormalities in most patients presenting with the condition; however, in some patients the abnormalities may appear so subtle on computed tomography that they can be easily overlooked or their true significance questioned. Magnetic resonance imaging has proved to be of great value in demonstrating the neuroanatomic anomalies underlying the visual handicap of this latter group of patients, allowing for early diagnosis and precise management.

CT of the stomach and duodenum. Part II: Pathology.

A survey is provided of the CT appearance of the pathological stomach based on a retrospective study on 262 patients. The CT appearance of gastric tumours, pancreatic pathology involving the stomach, oesophago-cardiac varices, ulcers, duodenal pathology is described. The results were compared with those of conventional barium meal examination. The possibilities and limitations of CT in the radiodiagnosis of the stomach are discussed.

CT of the stomach and duodenum. Part I: Anatomy and postoperative stomach.

A survey is provided of the CT appearance of the normal and postoperative stomach based on a retrospective study on 262 patients. The results were compared with those of conventional barium meal examination. Detailed understanding of the CT anatomy of the normal and postoperative stomach, as well as familiarity with the usual pitfalls, are imperative to guarantee correct interpretation of pathology.

Interobserver agreement in the assessment of lobar versus deep location of intracerebral haematomas on CT.

In patients with supratentorial intracerebral haemorrhage (ICH), it is important to discriminate superficial (lobar) and deep (basal ganglia) location, since this has consequences for research and prognosis. Haemorrhages at these sites have different causes and different risk factors. We studied the interobserver variation between three radiologists in classifying fifty large haematomas on CT as deep or lobar. The kappa values were almost perfect, ranging from 0.88 to 0.96. We conclude that the assessment of CT by radiologist is a reliable method to discriminate between lobar versus deep origin even for large intracerebral haematomas.

[Magnetic resonance cholangiopancreatography: sensitive and specific diagnostic method for suspected choledolithiasis]. / Magnetische-resonantiecholangiopancreatografie: sensitieve en specifieke onderzoeksmethode bij vermoeden van choledocholithiasis.

OBJECTIVE: To evaluate the role of magnetic resonance pancreaticography (MRCP) in the diagnostic process of common bile duct stones. DESIGN: Retrospective. METHOD: All 27 MRCPs performed in the period December 1997-December 1998 in the Deventer Hospital, the Netherlands, were evaluated using chart examination. The group comprised 11 males and 16 females with an average age of 57 years (SD 3.2) with anamnestic or biochemical cholestasis. If at MRCP stones were diagnosed, endoscopic retrograde cholangiopancreaticography (ERCP) was performed. If MRCP was without abnormalities, no further diagnostic procedures were performed. The findings at MRCP were compared with those at ERCP and with the clinical course. The MRCP examinations were performed on a 1.5 Tesla MR unit. RESULTS: In 16 patients MRCP was performed before laparoscopic cholecystectomy and in 5 there after. In 5 MRCP was performed to rule out a biliary cause of acute pancreatitis and in 1 patient because of an elevated alkaline phophatase after laparotomy for an abdominal stab injury. There was one false-positive MRCP result and no false-negative ones. Accordingly, the sensitivity of MRCP for choledocholithiasis was 100% and the specificity 95%.

Subtraction angiography of the orbit.

The principles and techniques of subtraction angiography are described. The superimposed confusing shadows are eliminated so that the small opacified arteries and veins as well as the choroidal plexus are clearly seen. The method is useful in the diagnosis of intraocular tumours and in localizing deeply seated intraocular foreign bodies.

Transfrontal perforation of the lamina terminalis.

Perforation of the lamina terminalis through a frontal burrhole in occlusive hydrocephalus is discussed, with details of technique, indications, and results. The follow-up of some patients who were treated between 1945 and 1955 is described in case reports.

The Netherlands' initial experience with NMR imaging.

A survey is provided of the first clinical results of NMR scanning with an experimental 0.14-Tesla resistive magnet system at Philips Medical Systems at Eindhoven. Between 1981 and 1983, 173 NMR examinations were performed on 43 healthy volunteers and 130 patients. The patients had a large variety of abnormalities, making statistical analysis invalid. Therefore this presentation is limited to a description of the different aspects of NMR imaging. The advantages and disadvantages of NMR scanning are discussed.

Early Legg-Perthes disease (ischemic necrosis of the femoral head) demonstrated by magnetic resonance imaging.

A case of early Legg-Perthes disease (ischemic necrosis of the femoral head) is presented to illustrate the value of magnetic resonance imaging (MRI) in demonstrating the presence of and extent of alterations of intensity of the ischemic femoral epiphysis compared with the normal. The unique advantages of flexible imaging planes and ability to perform follow-up examinations without the hazards of ionizing radiation are stressed.

Magnetic resonance imaging of the normal female pelvis.

9 healthy volunteers were examined by magnetic resonance imaging in order to describe the anatomy of the normal female genital tract as seen by this technique. The visualization of the bony and pelvic skeleton and the muscles surrounding these structures is excellent. Due to high contrast resolution relatively small structures like the femoral blood vessels can be positively identified. Imaging of the small bowel is disappointing. Visualization of the rectum and sigmoid colon is relatively good. In the uterine wall three distinct layers can be identified. An interpretation of the origin of these layers based on comparison with macroscopic and microscopic examination of sections of uterine tissue is given. Further research is needed to demonstrate possible cyclic changes in the appearance of the uterus. The ovaries could not be identified with certainty.

Magnetic resonance imaging of primary malignant bone tumors.

The authors report a retrospective study that suggests that MRI may be superior to CT for the preoperative evaluation of bone tumors.