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Biomedical subjects

D B Lewall

Publications and source records attributed to D B Lewall.

At least 19 recordsLinked to original sources
PubMed1998

Hydatid disease: biology, pathology, imaging and classification.

Rupture and the sequellae of rupture are more important than the mass effect of hydatid cysts, except in the brain where the mass effect by itself has severe consequences. The biology of hydatid disease, including the complex interaction between primary and secondary hosts, is reviewed. The hydatid cyst always starts as a fluid-filled, cyst-like structure (Type I) which may proceed to a Type II lesion if daughter cysts and/or matrix develop. In some instances the Type II lesion becomes hypermature and due to starvation dies to become a mummified, inert calcified Type III lesion. Type I and II lesions may undergo three types of rupture: contained, communicating and direct. Contained rupture is clinically silent, but communicating rupture may cause biliary obstruction and evacuation or infection of the cyst. Direct rupture has the greatest clinical consequences which include anaphylaxis, dissemination of hydatid disease (secondary hydatosis) within the host, and bacterial infection of the pericyst cavity. The clinical implications of the hydatid disease at different stages are discussed. A plea is made for the development of an international medical hydatid registry employing uniform nomenclature and consistent reporting in order to allow more rational comparisons of different types of management.

Animals↗
PubMed1998

Doppler ultrasound evaluation of advanced portal vein pulsatility in patients with normal echocardiograms.

The hypothesis tested that mechanisms other than retrograde transsinusoidal fluid wave transfer reported in patients with right heart failure are responsible for the ultrasonographic sign of advanced portal vein pulsatility (APP). Within a time-period of 3 years we have seen 13 patients with APP, defined as temporary portal flow reversal in the face of a normal echocardiogram. Nine of these patients had biopsy-proven liver cirrhosis and four with liver disease were without cirrhosis or cardiac pathology. A randomly selected control group of 18 healthy subjects was studied. Doppler ultrasound evaluation of the hepatic veins as well as the intra and extrahepatic portal vein territories was performed in both groups. Hepatopetal portal flow with APP reversed to hepatofugal flow in follow up studies in two patients. In another two hepatopetal flow with APP in the main portal vein and hepatofugal flow in the intrahepatic portal radicles was recorded during the same examination. The remaining group displayed APP in the intra and extrahepatic portal vein territories. None of the normal subjects presented with APP. Hepatic venous outflow obstruction associated with excessive arterioportal shunting is likely to account for APP of all of our patients. Based on a causal link between angiographic 'to-and-fro' flow pattern and the sonographic APP sign in patients with sinusoidal outflow obstruction we suggest, that APP expresses a short, transitional period of portal hypertension just before the occurence of flow reversal.

Adult↗
PubMed1998

Hydatid cysts of the liver: two cautionary signs.

The purpose of this paper is to evaluate the significance of two CT findings: evidence of an exophytic component of part of a hydatid cyst and dilated ducts in the vicinity of a cyst. The CT scans and clinical records of 63 patients were reviewed. There was evidence that cysts with an exophytic component are probably unstable and unsuitable for treatment by percutaneous drainage or prolonged medical treatment. Dilated pericystic ducts are a relative contraindication to nonsurgical treatment because of the danger of complicating biliary obstruction. Surgery should not be delayed unduly when either sign is encountered.

Adolescent↗
PubMed1996

Radiology in the neonatal intensive care unit: dose reduction and image quality.

This paper describes a prospective study of the diagnostic radiation doses received in a neonatal intensive care unit (NICU) for a representative radiological technique used at our institution for a number of years and a "low dose" technique similar to that recommended by the Commission of the European Communities (CEC). A 400 speed film-screen combination was used in both techniques. A total of 363 anteroposterior (AP) chest and abdominal films of 77 neonates were accrued. For each radiograph, the entrance skin dose (FSD), energy imparted (EI) and mean whole body dose were determined. For a neonatal AP chest, there was an 18% reduction in the mean ESD per radiograph from 20.0 muGy for the representative technique to 16.4 muGy for the low dose technique (p < 0.0005). The reduction in the mean EI per radiograph values for the two techniques from 7.9 muJ to 7.1 muJ (10%) was statistically significant at the p < 0.017 level, after compensating for the difference in mean field dimensions between the two patient cohorts. The mean whole body dose per radiograph reduction from 4.4 to 3.5 muGy (20%) was statistically significant at the p < 0.0028 level. It was determined that the ESD and EI could be fitted by an exponential function in the equivalent patient diameter, a single parameter indicative of neonate size. Absolute excess childhood cancer mortality risk per film was estimated using risk factors derived for fetal exposures. A "worst case" absolute excess mortality risk per chest radiograph was estimated to be 1.40 x 10(-7) for the conventional technique and was further reduced to 1.11 x 10(-7) for the low dose technique. A blind comparison of patient-matched film pairs for each technique was performed by three radiologists using criteria similar to those specified by the CEC. No statistically significant difference in clinical image quality was found between the two techniques.

Analysis of Variance↗
PubMed1995

A fluoroscopy credentialling programme for orthopaedic surgeons.

We have developed a teaching programme for non-radiologists who use fluoroscopy, which includes techniques for reducing the radiation received by the patient and the surgeon during orthopaedic procedures. The techniques resolve around the radiation protection concepts of time, distance and shielding. The programme has been very successful in reducing the total fluoroscopy times of orthopaedic surgeons; in our institute, durations have been reduced to about 10% of those before the training started. We review the aims and content of our programme.

Education, Medical, Continuing↗
PubMed1990

Endoscopic diagnosis and treatment of postoperative bronchopleural fistula.

The diagnosis and closure of small postresection bronchopleural fistulae can be accomplished with selective bronchography and placement of fibrin sealant through the flexible fiberoptic bronchoscope. This method of diagnosis and closure of the bronchopleural fistula avoids both general anesthesia and a thoracotomy. This technique is successful in small bronchopleural fistulae and patients with multiple postresection bronchial stumps.

Adult↗
PubMed1988

Prosthetic heart valve malfunction: plain film findings.

Clinical signs of heart valve malfunction are often not specific so that recognition frequently depends on nonclinical methods. The chest radiographs of 34 patients with 41 prosthetic valve malfunctions (PVM) were compared before and after valve failure. The most frequent sign of PVM is postcapillary hypertension (90%). A marked increase in heart size occurs with regurgitation but not with obstruction. A change in attitude of a valve of more than 6 degrees. in the aortic and 12 degrees in the mitral position is virtually diagnostic of dehiscence. This was seen in 52% of patients with paravalvular regurgitation and in 29% of all patients with PVM. When dehiscence is suspected on clinical or radiologic grounds the valve should be examined fluoroscopically. Changes in the azygos vein and the vascular pedicle of the heart and the development of pleural effusions are less useful signs of PVM. Although the chest radiograph is often not diagnostic of PVM, it may point to the need for definitive investigation.

Adult↗
PubMed1986

Rupture of echinococcal cysts: diagnosis, classification, and clinical implications.

The authors classify rupture of echinococcal cysts into three types: contained, communicating, and direct. Contained rupture occurs when only the parasitic endocyst ruptures and the cyst contents are confined within the host-derived pericyst. When cyst contents escape via biliary or bronchial radicles that are incorporated in the pericyst, the rupture is communicating. Direct rupture occurs when both the endocyst and the pericyst tear, spilling cyst contents directly into the peritoneal or pleural cavities or occasionally into other structures. Communicating and direct forms have more serious clinical implications than contained rupture, but even contained rupture should have prompt surgical attention to prevent it from developing into one of the other forms. Untreated communicating rupture of a liver cyst can lead to obstruction of the biliary system with a 50% mortality rate. Direct rupture may cause anaphylaxis, and it should be managed surgically, possibly with adjunctive treatment with antihelminthic drugs to decrease the possibility of metastatic hydatosis.

Adult↗
PubMed1985

Mycetoma.

A retrospective analysis was made of the radiologic features of 30 cases of mycetoma. Conventional radiographs, computerized tomography (CT), and isotope bone scans were assessed. Soft-tissue swelling was the only abnormality in 27%. Periosteal reaction was present in 67%, sclerosis in 53%, endosteal reaction in 50%, and cortical erosions in 43%. Cavities which were found in 33% are important as predictors of the causative micro-organism. Conventional radiographs are essential to the management of mycetoma as bone involvement makes non-surgical cure unlikely. The role of CT in diagnosis and management appears to be minor, except when the thigh is involved. Isotope bone scanning appears to have no value in either diagnosis or management.

Adult↗
PubMed1985

Hepatic echinococcal cysts: sonographic appearance and classification.

The sonographic appearance of echinococcal lesions of the liver was studied in 59 patients. We have proposed a classification of these lesions that reflects the pathology and natural history of the disease: type I, simple fluid-filled cysts; type IR, lesions containing undulated membranes that represent detached endocyst secondary to rupture; type II, lesions that contain daughter cysts and/or a formed echogenic material we call matrix; and type III, dead, densely calcified lesions. The natural progression of hepatic echinococcal cysts is from type I to type III. Daughter cyst formation is part of the natural aging process. When hydatid cysts are infected, they lose their characteristic sonographic appearance and become diffusely hyperechoic.

Adolescent↗
PubMed1979

Ultrasound evaluation of hydronephrosis of pregnancy.

Four hundred ninety-two patients, including 449 pregnant patients, 39 nonpregnant control patients, and 4 patients with pelvic masses, had renal ultrasonography using gray scale technique. Measurements of renal pelvic diameters in the normal pregnant patients revealed an overall incidence of 63 percent renal pelvic dilatation over the nonpregnant controls. Maximum normal renal pelvic diameters were 1.1 cm on the right and 0.9 cm on the left. The maximum normal expected renal pelvic diameter (97.5 percent confidence level) in pregnancy is 2.7 cm on the right and 1.8 cm on the left in the last two trimesters of pregnancy. There was no significant difference between primiparous and multiparous patients, but pregnant patients were significantly different from controls in every trimester (p less than 0.01). Maximum dilatation occurred at 24--28 weeks of gestation. The right renal pelvis was enlarged to the greatest degree in 90 percent of normal patients. Patients with pelvic masses showed a similar pattern of right-sided hydronephrosis.

Dilatation, Pathologic↗