Biomedical subjects
Publications and source records attributed to H Rigauts.
We determined the maximum closing capability of the internal anal sphincter muscle ring in vitro and in vivo. The internal sphincter, 4 to 6 mm thick, cannot close the anal canal hermetically, not even during maximal contraction. The blood-filled anal cushions have to fill up an intrasphincteric gap of at least 7 to 8 mm in diameter.
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The value of ultrasound (US) in determining the cause and site of biliary obstruction was critically evaluated and compared to endoscopic retrograde cholangiography (ERCP), in a prospective study performed on 120 consecutive patients. The final diagnosis was based on surgery, endoscopic retrograde cholangiography or a combination of other examinations. Ultrasound successfully differentiated obstructive from non obstructive jaundice in 96% of the patients, comparing well with the results ERCP. US correctly defined the cause of obstruction in 71% of the patients with ductal stones, in 90% of the patients with tumoural bile duct obstruction, but only in 59% of the patients with chronic pancreatitis.
The combination of a rapid single bolus injection (72 ml of a 60% concentrated iodinated contrast medium) with spiral scanning versus dynamic sequential scanning with a conventional biphasic bolus injection (150 ml of 60% concentrated iodinated contrast medium) is compared. 60 patients with normal pancreatic morphology were included in this study. 30 patients were examined with dynamic sequential scanning (cycle times of 5 seconds) during a biphasic bolus injection, 30 patients were examined with spiral scanning (cycle times of 1 second) after a single uniphasic bolus injection. For both scanning techniques, mean attenuation values of the pancreas were measured before and at different time intervals after contrast injection. The difference in attenuation values of the pancreas before and after contrast injection reflects the level of contrast enhancement in both methods. The level of contrast enhancement of the pancreas after bolus injection was not statistically significantly different in spiral scanning versus in dynamic sequential scanning. In comparison with conventional scanning, spiral scanning allows to reduce the injected dose of contrast by 50% without compromising the contrast resolution.
The study of a 70-year-old woman with fibrosing pancreatitis, an uncommon variety of chronic pancreatitis, presenting as a discrete solid mass in the head of the pancreas, is reported. CT and US were non-diagnostic while ERCP and MR detected a focal anomaly. This case report stresses the sensitivity of MR in some pancreatic pathologies.
An asymptomatic case of intrahepatic shunt between a portal and hepatic vein is presented. Ultrasound examination combined with Doppler sonography showed a communication between a dilated portal vein and a hepatic vein. Computed tomography and angiography confirmed the findings. Porto-hepatic venous shunting is very rare and has previously been reported in association with cirrhosis. The vascular malformation we present is believed to be a congenital anomaly, as no signs of cirrhosis or trauma were found.
The value of quantitative duplex Doppler sonography in discriminating the different possible causes of renal transplant dysfunction was prospectively studied in 60 patients during 65 episodes of renal function impairment. Final diagnosis at histology was acute rejection (n: 30), acute tubular necrosis (n: 4), cyclosporin nephrotoxicity (n: 16) and chronic rejection (n: 15). Duplex sonography was done the day a percutaneous biopsy was taken and before any therapy was started. Arterial Doppler signals obtained from the segmental, interlobar and arcuate arteries were both morphologically and quantitatively analysed. For quantitative analysis we used the resistive index as proposed by Pourcelot on the one hand, and introduced a variant resistive index on the other hand. Morphological analysis yielded no discriminative value. Comparing both quantitative methods--the resistive index of Pourcelot and the variant resistive index--clearly higher specificities--71% using the variant resistive index, 28% using the resistive index of Pourcelot--for excluding acute rejection from the other possible causes of renal function impairment could be achieved. A nephrectomy was done on 7 patients with severe transplant dysfunction. Microangiographies performed on these nephrectomy specimens were correlated with previous Doppler studies and with histology.
Outpatient myelography with iohexol (Omnipaque) was performed in 150 patients. Side effects were noted in 28 patients (19%), with only 3 (2%) major complaints. It concerned 2 patients with severe and prolonged headache and one patient with seizures. Side effects were not more frequent in outpatient myelography than in reported series of hospitalized patients. The frequency of side effects was significantly lower with the use of iohexol than in comparable studies with metrizamide. Headache was the most frequent side effect, followed by an increase or exacerbation of ischiatiform pain, nausea and vomiting. Side effects were slightly more frequent in cervical myelography than in lumbar myelography and were not related to underlying pathology. It is concluded that outpatient myelography is feasable for as far as iohexol is used and patient surveillance is carefully organized.
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A child 3 years of age is admitted to our hospital for surgical treatment of a lesion diagnosed elsewhere as an enchodroma. Our diagnostic studies revealed a case of spina ventosa. After five months of tuberculostatic treatment there is a clinical and radiological clear regression of the lesion. In order to prevent fistulisation and further unfavourable expansion of the lesion, the early diagnosis of this rare entity is mandatory.
A new method of CT is proposed: "volume scanning," produced by continuous table incrementation during continuous scanning. This approach was successfully implemented on a commercially available third generation scanner with continuous measuring system and slip ring technology (Somatom Plus; Siemens AG, Erlangen, F.R.G.). Different phantoms were scanned with volume scanning at different table incrementation speeds and with conventional scanning with standard sequential table incrementation. Comparison of the results showed that in volume scanning, a table incrementation speed equal to the slice thickness per second provides the optimal compromise between acquisition volume and level of artifact production. Different reconstruction parameters available were tested for optimal artifact reduction. A 240 degrees reconstruction angle offered the best results. Experiments on geometrical distortion and contrast resolution revealed hardly any difference between volume scans and conventional scans. Up to now volume scanning has been used in 20 patients. Images obtained in the thoracic, pelvic, and upper abdominal region show exceptionally sharp anatomical detail with minimal artifacts. Volume scanning opens new possibilities in fast sequential dynamic contrast studies in the abdomen and chest.
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