Fluid levels in medical imaging.

Fluid levels are commonly observed on a range of imaging methods in both normal and abnormal circumstances. Radiologists must be familiar with the appearances and significance of fluid levels, but more fundamentally, require an understanding of the mechanisms by which fluid levels occur and the principles necessary for the demonstration of fluid levels. These are the prerequisites of a cavity and at least two types of immiscible fluid, and most importantly, the requirement of an image that is orientated in the vertical plane.

A rare cause of spinal cord compression: imaging appearances of gout of the cervical spine.

Gout is a metabolic disorder typically affecting the peripheral joints, more commonly in males. Spinal involvement is uncommon and is usually associated with hyperuricemia. We present the imaging findings of a case of spinal gout in a female patient with no previous history of hyperuricaemia, involving multiple spinal segments.

Juvenile spondylolysis: a comparative analysis of CT, SPECT and MRI.

OBJECTIVE: To evaluate whether MRI correlates with CT and SPECT imaging for the diagnosis of juvenile spondylolysis, and to determine whether MRI can be used as an exclusive image modality. DESIGN AND PATIENTS: Juveniles and young adults with a history of extension low back pain were evaluated by MRI, CT and SPECT imaging. All images were reviewed blindly. Correlative analyses included CT vs MRI for morphological grading and SPECT vs MRI for functional grading. Finally, an overall grading system compared MRI vs CT and SPECT combined. Statistical analysis was performed using the kappa statistic. RESULTS: Seventy-two patients (mean age 16 years) were recruited. Forty pars defects were identified in 22 patients (31%), of which 25 were chronic non-union, five acute complete defects and ten acute incomplete fractures. Kappa scores demonstrated a high level of agreement for all comparative analyses. MRI vs SPECT (kappa: 0.794), MRI vs CT (kappa: 0.829) and MRI vs CT/SPECT (kappa: 0.786). The main causes of discrepancy were between MRI and SPECT for the diagnosis of stress reaction in the absence of overt fracture, and distinguishing incomplete fractures from intact pars or complete defects. CONCLUSIONS: MRI can be used as an effective and reliable first-line image modality for diagnosis of juvenile spondylolysis. However, localised CT is recommended as a supplementary examination in selected cases as a baseline for assessment of healing and for evaluation of indeterminate cases.

Percutaneous vertebroplasty: history, technique and current perspectives.

Percutaneous vertebroplasty is a safe and efficacious technique for the treatment of persistent pain from a fractured vertebral body. Injection of cement into the vertebral body is made after insertion of a large-bore needle, frequently by a trans-pedicular approach. Vertebroplasty is most commonly used to treat painful osteoporotic fracture resistant to conservative therapy, but may be helpful in other conditions such as malignant collapse. NICE guidelines are now available for this procedure, which is relatively new in the UK, but has been performed for more than 15 years in continental Europe.

The role of diagnostic radiology in compressive and entrapment neuropathies.

Diagnostic imaging is increasingly being utilised to aid the diagnosis of compression and entrapment neuropathies. Cross-sectional imaging, primarily ultrasound and magnetic resonance imaging, can provide exquisite anatomical detail of peripheral nerves and the changes that may occur as a result of compression. Imaging can provide a useful diagnostic aid to clinicians, which may supplement clinical evaluation, and may eventually provide an alternative to other diagnostic techniques such as nerve conduction studies. This article describes the abnormalities that may be demonstrated by current imaging techniques, and critically analyses the impact of imaging in diagnosis of peripheral compressive neuropathy.

Fully automated software to monitor wear in prosthetic knees using fluoroscopic images.

Total knee arthroplasty is now a widely accepted treatment for late-stage arthritis. Wear of the polyethylene layer in prosthetic knees is a known cause of implant failure. Early detection of wear may allow prediction of device failure. In this paper we describe a fully automated image processing algorithm to measure the minimum tibiofemoral joint space width (mJSW) for monitoring prosthesis wear radiographically. The femoral portion and tibial plate were automatically delineated and mJSW was calculated in each compartment. The software also delineated the tip of the prosthesis pin in order to make a magnification correction. The algorithm was tested with a set of triplicate acquisitions of 18 fluoroscopic knee images. The RMS standard deviation (RMSSD) for the triplicate measurements was calculated as a figure of merit. The RMSSD was 0.077 and 0.087 mm for the lateral and medial compartments. The computer successfully found the minimum JSW for both compartments in all 54 images. A single case (2% of total) required user interaction to correct for an obvious failure to delineate the prosthesis pin. We document a robust and precise tool for quantifying mJSW to monitor prosthesis wear.

A radiological technique for the assessment of wear in prosthetic knee replacements.

OBJECTIVE: Wear of the polyethylene insert is a well-recognised cause of implant failure in total knee replacements. The purpose of this study was to evaluate a simple, digital fluoroscopic technique for the assessment of wear in knee prostheses. DESIGN: Fluoroscopic images of knee prostheses were produced both of a phantom and in a patient group. Joint space thickness was measured by reference to a known diameter. Measurements were made to assess repeatability of positioning, inter-and intra-observer variance and the effect of angulation. RESULTS: Standard phantom images showed small variation between measurements, high inter-reader correlation (Pearson's correlation coefficient, r=0.98, P<0.001; coefficient of variation=0.53%) and low intra-reader variation (coefficient of variation=0.57%). Inter- and intra-imager variation were low (coefficient of variation=1.05% and 0.88%, respectively). In the patient group, the range of joint space measurements was 1.9-8.9 mm. The coefficient of variation in insert measurements on repeated images was 2.0%. Repeatability of measurements was 0.2 mm with 99% confidence interval. CONCLUSIONS: This technique allows repeatable, precise measurement of insert thickness. The technique may be adapted to any implant where a reliable calibrating distance is present.

Osteoma of the thyroid cartilage--an unusual cause of difficult intubation.

We describe a case of histologically proven osteoma of the thyroid cartilage that presented because of difficulty in intubation prior to coronary bypass surgery. To our knowledge, this is the first documented case in the English literature.

Giant ancient schwannoma of the pelvis.

A 43-year-old man with a large ancient schwannoma of the pelvis, presenting with varicose veins, is reported. Ancient schwannoma (neurilemmoma) is a benign tumour of nerve sheath origin characterised histologically by features of severe degeneration and which rarely can grow to a large size. Malignant transformation, though reported, is extremely rare.

Sonographic findings in the anterior interosseous nerve syndrome.

This report details previously undescribed sonographic findings in the anterior interosseous nerve syndrome. Loss of muscle bulk, increased reflectivity, reduced perfusion on Doppler sonography, and lack of active contraction of the affected muscles were observed. These findings can aid in the localization of the pathologic process and in the exclusion of tendon rupture. Dynamic observation of muscle function and Doppler changes after exercise can also help identify the muscles involved. Both sonography and MRI may be useful in the evaluation of patients with the anterior interosseous nerve syndrome and other peripheral neuropathies.

Women with normal mammography describing symptoms at screening.

A retrospective study from May 1989 to June 1995 identified 4327 women with symptoms and normal mammography, from a total population of 139,852. The women with symptoms were divided into two groups: those who had been recalled for assessment, because of potentially significant symptoms, and those who had not. Out of 448 women recalled for assessment with significant symptoms, 8 malignancies were detected and 8 benign biopsies were performed. Review of the remaining 3879 women with symptoms showed that 4 had developed interval cancers in the same breast as the symptoms described at the previous screening attendance. No cancer was detected at subsequent screening examinations. This review shows that breast cancer is so uncommon in women attending for screening with symptoms that a policy of only recalling women with significant symptoms is justifiable.

Lumbar hernia: a rare cause of large bowel obstruction.

We describe a 70-year-old woman presenting with large bowel obstruction secondary to incarceration of the mid descending colon within a lumbar hernia. This was diagnosed on barium enema and successfully treated surgically.

The ultrasound appearances of scrotal oedema.

Ultrasound has been shown to be a useful tool in the investigation of both acute and chronic scrotal conditions. We describe the ultrasound appearances of scrotal oedema with different aetiologies. A total of eight patients with scrotal oedema resulting from a variety of conditions, including heart failure, idiopathic lymphoedema, hepatic failure and lymphatic and venous obstruction, underwent ultrasound of the scrotum to determine the appearances common to each case. In all cases, similar appearances of a thickened scrotal wall with an 'onion' like appearance surrounding normal testicles was seen. The scrotal wall had a jelly like texture. Awareness of the typical appearances of scrotal oedema on ultrasound and a knowledge of its causes is helpful in distinguishing it from other causes of a swollen scrotum.

Antibiotic prophylaxis in patients undergoing radiological procedures who are at risk of infective endocarditis--do radiologists know what they are doing?

The British Society for Antimicrobial Chemotherapy has published guidelines recommending that all patients with prosthetic heart valves, or those with a previous history of bacterial endocarditis, should receive prophylactic antibiotics before procedures likely to cause a bacteraemia, due to the potential risk of bacterial endocarditis. The guidelines are widely available, notably in the British National Formulary. Two separate and independent surveys of radiologists in this Region showed that there was poor awareness of these guidelines and their implications for radiology departments.