The relationship between osteonecrosis of the proximal femur identified by MRI and lesions proven by histological examination.

Total hip replacement in patients with advanced osteonecrosis of the femoral head is often complicated by early loosening of the femoral component. Recent evidence has suggested that abnormal bone extending into the proximal femur may be responsible for the early failure of the femoral component. We aimed to identify which patients were at high risk of early failure by evaluating gadolinium-enhanced MR images of histologically-confirmed osteonecrotic lesions beyond the femoral head. Although the MR signal intensity has been shown to correlate well with osteonecrosis in the femoral head, it was found to be relatively insensitive at identifying lesions below the head, with a sensitivity of only 51% and a predictive value of a negative result of only 48%. However, the specificity was 90%, with the predictive value of a positive MRI finding being 86%. Only those patients with osteonecrosis of the femoral head secondary to sickle-cell disease, who are known to be at high risk of early loosening, had changes in the MR signal in the greater trochanter and the femoral shaft. This observation suggests that changes in the MR signal beyond the femoral head may represent osteonecrotic lesions in areas essential for the fixation of the femoral component. Pre-operative identification of such lesions in the neck of the femur may be important when considering hip resurfacing for osteonecrosis of the femoral head, following which early loosening of the femoral component and fracture of the neck are possible complications.

The ultrasound appearance of the normal psoas muscle.

One hundred and forty-four psoas muscles in 72 subjects were scanned to study the normal ultrasound appearance. For the purpose of description the psoas was divided into three sections. Ten of the 432 sections could not be adequately seen on ultrasound. The psoas demonstrated hyperechoic striations on a hypoechoic background typical of muscle. In addition the upper section, from the origin of the muscle to the lower pole of the kidney, contained echogenic planes in 15 (10%) and the mid section, from the lower pole of kidney to iliac crest, demonstrated prominent echogenic planes and focal areas of increased and decreased echogenicity in 65 (46%). The lower section, from the iliac crest to fusion with the iliacus, demonstrated a single echogenic plane in 96 (70.5%) which was best seen running obliquely in the transverse plane and in 40 (29.5%) there were more complex echogenic planes or focal areas of increased or decreased echogenicity. The cause of the prominent echogenic plane in the lower section was not apparent in the anatomical literature and therefore cadaveric dissection of nine psoas muscles was performed which demonstrated that the echogenic plane was caused by intramuscular tendon fibres formed from the more cranial origins of the psoas. The psoas minor was not identified as a separate structure.

The shoulder in sickle-cell disease.

Sickle-cell disease (SCD) is probably the commonest cause of avascular necrosis worldwide, and its prevalence appears to be rising in developed countries. Avascular necrosis of the humeral head is a common complication but has not been previously studied in detail. We have reviewed 138 patients with SCD for clinical, radiological and functional abnormalities of the shoulder, using a radiological classification designed for avascular necrosis of the shoulder. Radiographic lesions, frequently bilateral, were found in 28% and only 53% of patients had normal shoulder function. The management of this relatively common complication is difficult. Joint replacement is likely to fail and early diagnosis is important.

Radiological features during and following treatment of spinal tuberculosis.

A retrospective study was performed in order to document the sequence and time scale of radiological changes occurring during the healing of spinal tuberculosis. 28 episodes occurred in 26 patients, of whom only two were Caucasian. All demonstrated good response to conventional chemotherapy. Soft-tissue masses increased in size for up to 1.5 months and took about 12 months to resolve. Bone destruction was seen in all cases and progressed in 70% of patients, whilst on treatment. There was loss of vertebral body height in 79%, which progressed for up to 14 months; any recovery of height was a very late feature. Sclerosis was seen at presentation in 52% and developed in most of the remaining patients within 5 months of instigating treatment. It progressed for up to 14 months and took, on average, 31 months to return to normal. Reduction in disc height was commonly seen and the vertebrae fused in three-quarters of those affected, the time of onset of fusion being very variable. To manage patients with spinal tuberculosis, an appreciation of the variability of radiological changes that can occur during treatment is necessary.

Diaphragmatic muscular bundles (slips): ultrasound evaluation of incidence and appearance.

Diaphragmatic muscular bundles (slips) connect the central tendon of the diaphragm to the inner aspect of the lower thoracic cage. They cause hepatic invaginations which may be visualized at ultrasound (US) or computed tomography. Two hundred patients underwent prospective US of the diaphragm and liver to determine the incidence and characteristics of slips. The incidence was 15%, rising to 30% in those aged 80 years and over. Slips average 1.2 cm in depth (range 0.1-3.6 cm) and their occurrence has no racial or sexual bias. Multiple slips were seen in 4% of patients, all females. Slips are echogenic and have a variety of appearances, typically nodular on transverse section and strand-like longitudinally. Knowledge of these structures will avoid confusion with liver and peridiaphragmatic pathology.

The most advantageous timing of external ureteric compression during intravenous urography.

The objective of this study was to ascertain the most advantageous time during an intravenous urogram to apply external ureteric compression to gain the greatest calyceal distension. This was a prospective randomized trial of 60 patients, divided into three equal groups with compression applied immediately after injection, at 5 minutes and after the 5 minutes film had been viewed. Patients with the usual criteria for avoiding compression were excluded. A statistically significant improvement in calyceal distension occurred when compression was applied at 5 minutes compared with that applied after the 5 minute film had been viewed. No improvement was seen when the compression was applied immediately after injection. We recommend that external ureteric compression should be applied immediately after the 5 minute film.

Ultrasonography of splenic variants.

We report seven patients in whom unusual left upper quadrant abdominal masses were found on ultrasonography (US) and subsequently proven to be splenic variants. In five patients, a round discrete mass was present in the left suprarenal area, separate from a spleen which appeared to be normal. A sixth patient had multiple masses in the splenic region and a postsplenectomy seventh patient had a left posterior, para-aortic mass at the level of the renal hilum. Computed tomography (CT) confirmed the presence of the mass in four patients. In two, the mass was biopsied. Confirmatory radionuclide liver and spleen scans were performed in six patients. Single-photon emission CT proved to be most specific by demonstrating functioning splenic tissue in the region of the masses. Knowledge of the normal anatomy and embryology of the spleen readily explains the findings in our patients. Splenic variants should be considered in the differential diagnosis of problematic, left upper quadrant masses seen on US.

Ultrasonic characterization of selected renal tissues.

Velocity, attenuation, and backscatter of ultrasound were measured in human renal tissues over a frequency range relevant to clinical imaging (3.5-7 MHz). Normal renal tissues, as well as three types of mass (angiomyolipoma, renal cell carcinoma, and oncocytoma) were studied, and comparisons made of the appearance of the tissues in clinical images to their ultrasonic and pathological properties. The results showed angiomyolipoma had high attenuation and backscatter coefficients due to acoustic impedance differences between fat and smooth muscle components of the tumour. The renal cell carcinomas were indistinguishable from normal kidney tissue, except in one case where infiltration by fatlike macrophages led to high attenuation and backscatter coefficients. This finding also supports the conclusion that fat/nonfat interfaces are a dominant scatter mechanism in renal tissues.

Hypodense colloid cyst of the third ventricle.

The diagnosis of colloid cysts of the third ventricle using computed tomography (CT) rarely causes problems. The typical well-rounded, hyperdense mass in the anterior part of the third ventricle is usually well shown, along with the associated lateral ventricular dilatation. However, it is also well recognized that these cysts may be isodense, and this can on occasion lead to diagnostic difficulty. Rarely have hypodense colloid cysts been reported. We describe two patients in whom the low density of the tumors led, initially, to a failure to identify them on the CT scan. Although this is an atypical appearance, it is important to be aware of it, as colloid cysts which are surgically curable have a definite morbidity and mortality if untreated.

The role of routine intravenous urography in patients with primary hyperparathyroidism.

The plain abdominal radiographs and intravenous urograms of 72 patients with primary hyperparathyroidism were reviewed. Renal tract calcification was detected on plain abdominal radiographs in 27 patients (38%), and intravenous urography revealed no calculi not detected on the plain radiographs. Intravenous urography did, however, show abnormalities not detected on plain abdominal radiographs in 22 patients (37%), but these findings influenced clinical management in only five patients (7%). In these five patients there were indications other than primary hyperparathyroidism for performing an intravenous urogram. Intravenous urography incurs a small risk and should not be performed as a routine investigation in primary hyperparathyroidism.

Visualisation of left atrial thrombi by coronary arteriography.

Abnormal vascularity in the region of the left atrial appendage was demonstrated by coronary arteriography in 5 patients with mitral stenosis. Subsequently, three of these patients proceeded to operation, and left atrial thrombi were confirmed in all three cases. Neovascularity must be differentiated from congenital fistulae, tumours, and coronary artery disease. Thrombus in the left atrial appendage is difficult to diagnose even with the use of cross-sectional echocardiography and may occasionally be demonstrated by coronary arteriography.

Ascending lower-limb phlebography: a comparative study of Hexabrix 320, iohexol 300 and iohexol 240.

A prospective, randomised study on 60 legs in 45 patients examined by ascending lower-limb phlebography was conducted to compare Hexabrix 320 (May and Baker Ltd), iohexol 300 and iohexol 240. The quality of opacification of the veins, side-effects, cost and amount of contrast agent used were compared. All three agents produced adequate examinations. Iohexol 300 was preferred for its denser opacification. Iohexol 240 was associated with the lowest incidence of side-effects and Hexabrix 320 cost the least per examination.

Contrast media osmolality and plasma volume changes.

A theoretical and experimental study of the plasma volume expansion consequent on the hyperosmolality of contrast media is presented. In the case of the ratio 1.5 media theory and experiment coincide closely but in the case of the ratio 3 media the observed changes exceed the predicted. It is proposed that this is due partly to the slower diffusion of the ratio 3 media out of the intravascular space and partly due to the fact that the osmotic load presented by these media is greater than would be expected from a study of their commercial solutions in which osmolality is reduced by molecular aggregation. The implications for the relative haemodynamic effects of different contrast media are discussed. The osmotic effects of contrast media also play a part in determining the image quality achievable in intravenous digital subtraction angiography (IV-DSA). It is predicted that ratio 3 contrast media will give better quality images in IV-DSA than ratio 1.5 media.

Radiographic features in patients with pulmonary manifestations of the acquired immune deficiency syndrome.

The radiographic findings in 14 episodes of pulmonary pathology, occurring in 13 patients with the acquired immune deficiency syndrome (AIDS) are described. The patients presented over a 15-month period. All were homosexual men with serum antibodies to human T-cell lymphotrophic virus III. Pneumocystis carinii pneumonia was the most common manifestation, occurring in seven of the 14 episodes. Radiographic appearances in five of these were classical, with bilateral perihilar ground-glass shadowing initially. In one the appearances were complicated by a superadded bacterial infection and in one the chest radiograph was normal. Bacterial infections occurred in five of the 14 episodes and, when present, showed the characteristic radiographic appearances of the causative organism. Three patients had widespread Kaposi's sarcoma. Bronchoscopy, broncho-alveolar lavage and transbronchial biopsy were often necessary to identify the causative agent. They were also indicated when atypical radiographic appearances occurred during the course of treatment as additional organisms could be found. The radiographic appearances of the conditions reported are felt to be sufficiently characteristic for the radiologist to play a useful role in suggesting the diagnosis and in monitoring the progression of disease in these patients.

Contrast-medium-induced acute renal failure and Tamm-Horsfall proteinuria.

An acute obstructive nephropathy due to precipitation of urinary glycoprotein-contrast complexes in the renal tubules has been postulated to explain the episodes of renal failure occasionally seen following intravascular contrast medium administration. In an in vitro study we were unable to produce any precipitation of contrast-glycoprotein complexes over a wide range of concentrations, temperatures and pH values in urine with any urographic contrast agent, conventional or new. Meglumine ioglycamide (Biligram: Schering) alone, the strongly protein-binding agent, exhibited the phenomenon, and only in high concentration. It is concluded that such a mechanism is unlikely to play a role in contrast medium nephrotoxicity, which therefore remains unexplained.