An evaluation of the role of nuclear medicine imaging in the diagnosis of periprosthetic infections of the hip.

AIM: To validate the role of nuclear medicine (NM) imaging in hip periprosthetic joint infection (PJI) of hip arthroplasties. MATERIALS AND METHODS: This was a retrospective study of 235 consecutive patients referred to NM for investigation of a symptomatic hip prosthesis. Imaging comprised Tc-99m bone scintigraphy, In-111 white cell scintigraphy, and bone marrow scintigraphy if required. Imaging findings were compared with intraoperative microbiology and histology, clinical findings and follow up for ≥ 24 months. RESULTS: There were 14 exclusions. Of the 221 remaining patients, there were 16 true positives, one false positive, 200 true negatives, and four false negatives. The algorithm used at this centre demonstrated an accuracy of 97.7% with high specificity of 99.5% and sensitivity of 80%. CONCLUSION: When modern NM techniques and accurate reporting criteria are used, scintigraphy is an effective tool for diagnosing PJI of the hip. NM is only given a marginal role in the recent American Association of Orthopedic Surgeons guidelines, and the orthopaedic community should reconsider their evaluation of this technique.

A meningeal myofibroblastic neoplasm related to solitary fibrous tumour and associated with a malignant neuroblastic element.

BACKGROUND: Solitary fibrous tumour (SFT) is a rare mesenchymal tumour now described at many locations, including the meninges. Intracranial SFT closely resembles meningioma clinically and radiologically, and, like meningioma, reports of meningeal SFT suggest a relatively benign behaviour after complete resection. Histopathological features distinguishing SFT from meningioma include variable cellularity, spindle cells arranged in fascicles, staghorn blood vessels and immunopositivity for CD34. CLINICAL PRESENTATION: The case is reported of a 60-year-old man with an anterior cranial fossa meningeal-based mass, which was resected. Histology showed some features in common with SFT (variable cellularity, spindled morphology, CD34 expression), but included an epithelioid element with cytokeratin and desmin immunopositivity, and lacked the characteristic vascular pattern of SFT. Histological features of meningioma were lacking. Recurrence of the tumour with extracranial extension 9 years later resulted in death of the patient. Histological examination revealed similar biphasic epithelioid and spindled CD34-immunopositive appearance to the earlier tumour, but in addition showed a high-grade element resembling olfactory neuroblastoma. CONCLUSION: This case report is of a meningeal-based mesenchymal neoplasm with histological similarities to SFT. Its morphology and immunophenotype, however, are distinct from SFT and hence it is proposed that it is a newly described entity. In addition, recurrence of the tumour with a high-grade neuroblastic element has, to our knowledge, not previously been described in SFT.

SPECTCT cerebral perfusion scintigraphy; is the low-dose CT component of diagnostic value?

AIM: To assess the potential diagnostic value of the low-dose computed tomography (CT) component of dual-examination single photon emission CT and CT (SPECTCT) cerebral perfusion studies. METHOD AND MATERIALS: Two hundred and forty consecutive 99 mTc hexamethylpropylene amine oxime (HMPAO) SPECTCT studies were considered for inclusion. The images were acquired on a hybrid dual-head gamma camera/low-dose CT system. The CT component had a fixed tube current of 2.5 mA. The CT section thickness was 5mm and total acquisition time approximately 7.5 min. Studies in which no CT images were acquired, or those excessively degraded by movement artefact were excluded. The CT images of each of the remaining studies were retrospectively reviewed and categorized as normal or abnormal. Details of the abnormalities were recorded. RESULTS: Fifteen of the 240 studies were excluded as no CT images were obtained. A further 14 were excluded as they were considered excessively degraded by movement artefact. A single abnormality was demonstrated on 48 (23%), and two abnormalities on four (2%) of the remaining 211 studies. The most common abnormal findings were low attenuation in the deep cortical white matter (n=22), infarcts (n=12), cerebral atrophy (n=7), dilated ventricles (n=5), basal ganglia calcification (n=4), and post-surgical change (n=3). Other findings included a chronic subdural haematoma, a meningioma, and a posterior fossa cyst. Previous cerebral imaging was available for comparison in 31% of cases. There was 85% concordance between previous imaging and the low-dose CT images. CONCLUSION: Twenty-five percent of the low-dose CT images in this study demonstrated abnormalities. Therefore the CT component of cerebral perfusion SPECTCT investigations should be routinely reported in their own right.

CT in pseudomyxoma peritonei: a review of 17 cases.

AIM: To describe the computed tomography (CT) findings in pseudomyxoma peritonei. MATERIALS AND METHOD: Two observers independently and retrospectively reviewed the CT images of 17 consecutive patients (nine women, eight men, mean age 53 years) with histologically proven pseudomyxoma peritonei. RESULTS: Six patients had small volume disease where pseudomyxoma peritonei was present in focal collections in the peritoneal cavity. Eleven had large volume disease that completely, or almost completely, filled the peritoneal cavity. Pseudomyxoma peritonei is characterized by low attenuation mucinous ascites on CT. Areas of high attenuation, septae and calcification are seen more commonly within it as the volume of disease increases. The pattern of accumulation of pseudomyxoma peritonei follows the normal flow of peritoneal fluid. It initially seeds at sites of relative stasis and as large volume disease develops it fills the remaining spaces in the peritoneal cavity and pressure effects dominate imaging. Pseudomyxoma peritonei may extend into hernial orifices or the pleural cavity. CONCLUSION: Pseudomyxoma peritonei is difficult to diagnose clinically. However, the pattern of accumulation of disease is predictable and can be recognized on CT.

Venous impulse foot pumps: should graduated compression stockings be used?

It is not known whether the effect of Foot Pumps (Novamedix, Andover, UK) is enhanced by simultaneous use of graduated compression stockings (by controlling calf compliance) or hindered (by restricting preload). To address this question, we studied 20 healthy volunteers with duplex ultrasound. The peak velocity in the popliteal vein was measured at rest with the legs flat, foot-up, and foot-down, then it was measured when the AV Impulse Foot Pump was activated. These measurements each were performed with and without graduated compression stockings. In each leg position, the use of simultaneous graduated compression stockings reduced the peak velocity. On physiologic grounds, graduated stockings should not be used simultaneously with Foot Pumps.

'Cable-maker's clavicle': stress fracture of the medial clavicle.

A 50-year-old man presented with a non-traumatic painful swelling over the medial clavicle. Radiographs showed a poorly defined fracture and the possibility of an underlying pathology was raised. Computed tomography suggested a stress fracture. This prompted a further, more detailed occupational history to be obtained from the patient, which revealed a hitherto undescribed cause of clavicular stress fracture and obviated the need for further imaging or biopsy.

Contraindications to metformin therapy in patients with NIDDM.

OBJECTIVE: Treatment with metformin is occasionally associated with the development of severe lactic acidosis. However, this is usually observed in patients with major contraindications to the drug. In this study, we aimed to determine the prevalence of conditions currently regarded as either contraindications or cautions to the use of metformin in patients with NIDDM. RESEARCH DESIGN AND METHODS: The case notes of metformin-treated NIDDM patients (mean age 62 years) attending a United Kingdom university hospital diabetes clinic over a 3-month period were reviewed according to criteria reflecting a pragmatic view of current prescribing recommendations. RESULTS: Of 89 consecutive patients whose notes could be evaluated in detail, only 41 (46%) had no contraindications or cautions to metformin whatsoever. Concomitant chronic disorders associated with a potentially increased risk of hyperlactatemia were renal impairment (n = 2; plasma creatinine concentrations 1.7 and 2.3 mg/dl, respectively), cardiac failure (n = 2), and chronic liver disease (n = 2). Other potentially relevant disorders included ischemic heart disease (n = 20), clinical proteinuria (n = 14), peripheral vascular disease (n = 22), and pulmonary disease (n = 7). Multiple conditions (i.e., two, three, or four) were present in eight, five, and one patient(s), respectively. CONCLUSIONS: More than half the patients in our series had concomitant conditions or complications conventionally regarded as cautions or contraindications to metformin; approximately 10% had a multiplicity of such conditions. Regular surveillance is necessary to detect the development of complications such as renal impairment. Vigilance is also required in view of the increased risk of major intercurrent illnesses, which may independently disturb lactate metabolism in patients with NIDDM. Metformin should be withdrawn promptly under such circumstances.