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Biomedical subjects

J A Webb

Publications and source records attributed to J A Webb.

At least 73 records · Page 4Linked to original sources

Lacunae: a urographic finding in chronic obstructive uropathy.

Lacunae, small spaces in the renal sinus that communicate with the caliceal fornices, have been mentioned rarely in the radiologic literature. These lesions have been reported to opacify during excretory urography in patients with current or previous urinary obstruction. Lacunae have been presumed to form in response to urine extravasation through the fornices, but there has never been gross anatomic or histologic proof of their existence. In two patients with obstructive uropathy, urographic-pathologic correlation confirmed the existence and nature of lacunae. On excretory urography, the appearance is likely to be confused with papillary necrosis.

Chronic Disease↗

Imaging of renal cystic diseases.

The improved understanding of hereditary cystic diseases is changing the nomenclature used to describe these diseases. Detailed family studies of the inheritance of these conditions become possible as the genes involved, or their DNA markers, are identified. At the same time, ultrasonography allows cystic disease to be detected very early in life in some patients. The new information necessitates changes in the terminology, which was based previously on the patient's age at clinical presentation. Thus, because ultrasonography now sometimes identifies the cysts of adult polycystic kidney disease in utero or in neonates, the term autosomal dominant polycystic kidney disease is now more appropriate. Similarly, the term autosomal recessive polycystic kidney disease is replacing infantile polycystic kidney disease. Despite the success of ultrasonography in identifying the cysts of these and other inherited conditions very early, it is important to appreciate that precise definition of the type and heredity of the condition concerned requires detailed pathologic and genetic studies. The other renal cystic disease receiving considerable attention in the recent literature is acquired cystic disease, about which more data are accumulating. With increasing numbers of patients on long-term dialysis, the condition and its complications, especially renal adenocarcinoma but also hemorrhage, continue to cause concern. The evidence for an increased incidence of renal cell carcinoma has strengthened over recent years, and the debate on the need for CT screening of patients on long-term dialysis continues.

Diagnostic Imaging↗

CT in renal and perirenal lymphoma: a further look.

The CT appearances of renal and perirenal lymphoma detected in 26 patients are presented. Twenty-four patients had non-Hodgkin's lymphoma and two patients Hodgkin's disease. This represented 3% of all patients scanned for routine staging of known lymphoma. Eleven patients had involvement at the time of relapse only, having had no previous evidence of renal involvement. Forty-three per-cent of all patients with renal lymphoma had no retroperitoneal lymph node involvement. Most patients had other extranodal disease at the time of presentation, most commonly bone.

Hodgkin Disease↗

Magnetic resonance imaging in idiopathic retroperitoneal fibrosis: measurement of T1 relaxation time.

Magnetic resonance imaging at 0.08 Tesla was performed in nine patients with proven idiopathic retroperitoneal fibrosis. A total of 11 scans was performed. Three patients were scanned before diagnosis; one of these also had two follow-up scans. A further six patients were scanned a variable time after diagnosis and treatment. On each scan, a periaortic soft-tissue mass was readily identified, the distribution corresponding to that seen on computed tomography. There was no difference in the mean T1 relaxation time of the mass between patients scanned before diagnosis and those scanned after treatment. However, the patient followed with serial scans showed a progressive reduction in the T1 value of the mass with time. Comparison with results obtained in patients with lymphoma suggests that the T1 values in retroperitoneal fibrosis are lower than in lymphoma, particularly non-Hodgkin's lymphoma.

Adult↗

Oral urea in the treatment of secondary tumours in the liver.

Twenty patients with secondary liver tumours, predominantly from colorectal carcinoma, were treated with oral urea at a daily dose of 8 gm-2. Treatment was well tolerated without side-effects. No objective responses were seen. It is concluded that oral urea is ineffective in the treatment of liver metastases from colorectal cancer.

Administration, Oral↗

Low field strength magnetic resonance imaging of the spleen: results from volunteers and patients with lymphoma.

Low field strength (0.08 Tesla) magnetic resonance imaging (MRI) of the spleen with spin lattice relaxation time (T1) measurement was performed on a total of 79 healthy volunteers and 62 patients with lymphoma. Inhomogeneity was observed on the T1 images of the spleen from 25 volunteers. This was therefore considered a normal variant. The normal range of spleen T1 at 0.08 Tesla was established (362-420 msec). No influence of age on spleen T1 was detected. The range of T1 values observed in males and females was similar, although the mean spleen T1 for females was significantly longer than that for males. The sensitivity of T1 measurement for the detection of lymphoma in the spleen was poor, particularly for patients with Hodgkin's disease. In a minority of untreated patients, however, a spleen T1 value outside the normal range may indicate the presence of lymphoma in the spleen. A significant decrease in spleen T1 following treatment was observed in 9 patients who underwent serial scanning.

Adolescent↗

Low field strength magnetic resonance imaging of bone marrow in patients with malignant lymphoma.

Detection of bone marrow infiltration by lymphoma with low field strength magnetic resonance imaging (MRI) has been assessed. Measurements of spin lattice relaxation time (T1) were made in 31 patients with lymphoma and compared with the results of bone marrow biopsy and with T1 measurements made on 90 healthy volunteers. The sensitivity of MRI was excellent in patients for whom the microscopic pattern of marrow infiltration was diffuse, but poor in those with microscopically focal infiltration.

Adult↗

In-vivo measurement of spin lattice relaxation time (T1) of bone marrow in healthy volunteers: the effects of age and sex.

Magnetic resonance images of the spine, sternum, femoral heads and upper femoral shafts were obtained from 90 healthy volunteers to determine the normal ranges of spin lattice relaxation time (T1) for different regions of the bone marrow. The influence of age, sex and oral contraceptive usage on bone marrow T1 was assessed. Differences observed between the T1 of the various regions of the bone marrow examined were consistent with the expected distribution of erythropoietic cells and fatty marrow. Bone marrow T1 was found to decrease with age, significantly lower mean T1 values being observed in subjects over 40 years of age than for those in the 20-40 years age group. The mean bone marrow T1 of females in the 20-40 years age group was significantly higher than that for males of comparable age. For subjects over 40 years of age, the difference in bone marrow T1 observed between males and females was not significant. Oral contraceptive usage had no effect on bone marrow T1.

Adult↗

In-vivo measurement of spin lattice relaxation time (T1) of liver in healthy volunteers: the effects of age, sex and oral contraceptive usage.

Magnetic resonance imaging of 81 healthy adult volunteers has been undertaken to establish the normal range of liver spin lattice relaxation time (T1) at 0.08 tesla. The influence of age, sex and oral contraceptive usage has been assessed. Liver T1 decreased with age. The mean liver T1 of subjects under 40 years of age was significantly longer than that of older subjects. A wider range of T1 values was observed in the younger age group. No difference in T1 was found between males and females who were not oral contraceptive users. The mean liver T1 of females who were taking the pill was significantly longer than that of females of similar age who were not oral contraceptive users. Serial examinations of eight oral contraceptive users showed that mean liver T1 values were significantly longer in the 3 weeks during which they were taking the pill than during the week off the pill.

Adult↗

Computed tomography in the follow-up of retroperitoneal fibrosis.

Serial abdominal computed tomography (CT) scans have been performed in 15 patients with biopsy-proven idiopathic retroperitoneal fibrosis. Twelve patients had abdominal CT both before diagnosis and at a variable time later. All 12 patients showed a decrease in the size of the retroperitoneal mass at follow-up, although two had not been treated with steroids. The remaining three patients who had abdominal CT at some stage after diagnosis all showed a small residual retroperitoneal mass. Based on the findings, guidelines for the use of CT in the follow-up of retroperitoneal fibrosis are discussed.

Adult↗

Magnetic resonance imaging as a screening procedure for methotrexate induced liver damage.

Spin lattice relaxation time (TI) measured with a low field strength magnetic resonance imager in 51 patients with severe psoriasis did not correlate with the histological findings of liver biopsies taken during treatment with oral methotrexate. Liver TI measurement at low magnetic field is of no value as a screening procedure in monitoring methotrexate induced liver damage.

Adolescent↗

The accuracy and limitations of ultrasound in the assessment of venous extension in renal carcinoma.

Ultrasound was used to assess venous extension in 28 patients with renal carcinoma, with particular reference to involvement of the inferior vena cava. The findings were correlated with surgical findings in all except two patients who had gross caval involvement and metastatic disease and in whom surgery was considered inappropriate. In 10 of the 28 patients (36%), a diagnostic ultrasound examination of the cava from the renal veins to the diaphragm was obtained. In four of these, ultrasound showed tumour involvement of the vena cava. In 12 cases (43%) only the intrahepatic part of the cava was seen, but the examination nonetheless excluded tumour involvement of the upper cava. Visualisation of the vena cava was impossible in six cases (21%), usually because of bowel gas or obesity; CT scanning provided valuable additional information in two of these cases. Inferior vena cavography confirmed the findings of the less invasive imaging procedures in 10 patients and was falsely positive once. Cavography is now seldom necessary in the assessment of renal carcinoma.

Aged↗

Reproducibility of spin lattice relaxation time (T1) measurement using an 0.08 tesla MD 800 magnetic resonance imager.

The reproducibility of T1 measurements using an MD 800 magnetic resonance imager operating at 0.08 T (3.4 MHz) has been assessed by repeated imaging over a 15-week period of a phantom containing six copper-sulphate solutions of different dilutions. The standard pulse sequence of this scanner with an inversion time of 200 ms and a repetition time of 1 s was used. Reproducibility was excellent for the lower T1 range (less than 350 ms), but greater variability was observed at higher T1 values (greater than 490 ms). A linear relationship between T1 and temperature has been demonstrated and a method for standardising T1 values obtained at different temperatures is described.

Magnetic Resonance Spectroscopy↗

Detection of spread of malignant lymphoma to the liver by low field strength magnetic resonance imaging.

The accuracy of spin lattice relaxation time (T1) measurement obtained with a low field strength magnetic resonance imager for the detection of spread of malignant lymphoma to the liver was assessed. The results of histological examination obtained at open liver biopsy were compared with liver T1 values in 27 patients with lymphoma. The normal range for T1 was established by scanning 61 healthy volunteers. Magnetic resonance imaging was highly sensitive in detecting hepatic lymphoma, all seven patients with liver lymphoma proved by biopsy having considerably higher T1 values. Specificity was less good. Five out of 20 patients with no histological evidence of hepatic lymphoma had abnormal T1 values. this level of sensitivity is considerably better than that reported for other imaging methods and contrasts with the results of one previous study using a different magnetic resonance system. Low field strength magnetic resonance imaging may prove to be a useful screening test in patients with lymphoma. The presence of a normal liver T1 seems to be a reliable guide to the absence of hepatic disease.

Adolescent↗

Hemorrhagic angiomyolipoma of the kidney.

Hemorrhage within a renal angiomyolipoma alters its characteristic appearance. We present a case diagnosed preoperatively with computerized tomography and ultrasound.

Female↗