Promising Role of Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Human Immunodeficiency Virus Associated Non-Hodgkin's Lymphoma.

This case report explores the potential role of FDG PET/CT in HIV -associated systemic non-Hodgkin's lymphoma (HIV-NHLs). In our locality, there are a cumulative total of 5523 reported HIV infections cases since 1984. We reported a case of HIV-related Burkitt's lymphoma (BL) and a case of diffuse large B-cell lymphoma (DLBCL) that underwent PET/CT examination in our PET centre. In HIV-NHLs patients, we must be reminded that not all hypermetabolic foci represent lymphomatous lesions. There is a close correlation between the pattern of lymphoid tissue activation in FDG PET/CT and HIV progression in patients without HIV-related malignancy. The unique patterns of lymphoid tissue activation observed in HIV-infected patients have great clinical implications. Secondly, HIV-infected patients are prone to suffer from opportunistic infections due to immunosuppression, particularly in those with high levels of HIV viral loads. FDG PET/CT cannot reliably differentiate metabolic active lymphoma from other benign diseases such as inflammation in the context of low CD4 count and high viral loads. In those cases, benign markedly hypermetabolic foci can be erroneously interpreted as lymphoma, particularly in those normal-sized lymph nodes. Furthermore, FDG PET/CT may be useful for assessing the efficacy of HAART in suppressing HIV replication and detecting its complication such as lipodystrophy. FDG PET/CT may play a potential useful role in staging and management of HIV -associated systemic non-Hodgkin's lymphoma. Plasma variables such as viral loads and CD4 count must be taken into account during image interpretation. FDG PET/CT as a potential useful tool for diagnosis, treatment response assessment and disease relapse detection in HIV -associated systemic non-Hodgkin's lymphoma worth to be further explored.

Prevalence of detecting unknown cerebral metastases in fluorodeoxyglucose positron emission tomography/computed tomography and its potential clinical impact.

To determine the prevalence of incidental finding of unknown cerebral metastases and explore the clinical impact of detecting unknown brain metastases among individuals underwent whole body fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) with brain included in field of view. A retrospective review of 1876 patients who underwent whole body PET/CT examination in our clinical PET center for oncological evaluation from January 2009 to September 2009 was performed. The total number and prevalence of unknown brain metastases detected by PET/CT were calculated. Patients diagnosed with cerebral metastases by PET/CT were further analyzed via the electronic patient record system for relevant clinical and radiological findings. Positive predictive value of PET/CT for the diagnosis of cerebral metastases was calculated with reference to contrast enhanced magnetic resonance imaging (MRI) or contrast enhanced CT. Of the 1876 subjects, 71 patients (3.8%) were diagnosed with cerebral metastases by PET/CT. 31 patients were already diagnosed with brain metastases before PET/CT. Among the 40 patients with unknown brain metastasis, 24 (60.0%) underwent either MRI (n = 5) or CT (n = 19) after PET/CT, of which 17 patients were confirmed with cerebral metastases. The true positive rate was 70.8% (17/24), while the false positive rate of PET/CT was 29.2% (7/24). Nearly 94.1% (16/17) patients with confirmed cerebral metastases on MRI or CT had subsequent change in management. Among the remaining 16 patients with positive findings of cerebral metastases without further radiological correlation, 43.8% (7/16) patients had change in management after PET/CT. A total of 57.5% (23/40) patients had change in management after PET/CT. The point prevalence of detecting unknown cerebral metastases by PET/CT was 2.1% (40/1876). 94.1% patients with newly diagnosed brain metastases confirmed with either MRI or CT received immediate treatment for cerebral metastasis in this retrospective study. PET/CT demonstrated significant clinical impact by identifying cerebral lesions with mass effect and hence that timely treatment was offered.

What does the future hold for the treatment of Fuchs endothelial dystrophy; will 'keratoplasty' still be a valid procedure?

Fuchs endothelial corneal dystrophy (FECD) is a well recognized corneal disorder characterized by the presence of collagenous warts extending from Descemet membrane (guttae) and endothelial cellular dysfunction due to cell loss and/or degeneration. Because of the characteristic abnormal cell morphology as seen with specular microscopy as well as the limited regenerative capacity in vivo, the endothelial cells were considered to be 'dystrophic'. Hence, FECD is commonly managed by replacement of the endothelium with donor tissue by means of a penetrating or endothelial keratoplasty. The latter procedure has now been refined to the isolated transplantation of a donor Descemet membrane and its endothelium, referred to as Descemet membrane endothelial keratoplasty (DMEK). Unexpectedly, clinical observation made after DMEK seemed to challenge the current concept of the state of the endothelium in FECD; we actually observed an important role for the 'dystrophic' host endothelium in re-endothelialization of the denuded DM, and subsequent corneal clearance. In addition, recent studies regarding the pathophysiology of FECD made us realize that the endothelial cells are not 'dystrophic' per se, but in the course of time may have acquired a dysfunction instead. This paper describes the rationale behind this new concept and based on this, discusses the possibilities for future, less invasive treatment modalities for FECD.

Thyrotoxicosis: a rare presenting symptom of Hurthle cell carcinoma of the thyroid.

Hurthle cell carcinoma of the thyroid is a rare type of thyroid neoplasm. The most common clinical presentation is a single palpable thyroid nodule. The neoplasm typically presents as a nonfunctioning or cold nodule on a Tc-99m sodium pertechnetate or radioiodine thyroid scan. We report a case of Hurthle cell carcinoma of the thyroid in a woman presenting with thyrotoxicosis. The Tc-99m thyroid scan was also interesting in that the nodule was a hot or hyperfunctioning area, resulting in a rare scintigraphic finding in a rare tumor. Clinicopathologic aspects and related issues are further discussed.

The effects of different dosages of oestrogen on the bone mineral density of postmenopausal Hong Kong Chinese women: randomised controlled trial.

OBJECTIVE: To determine the effects of different dosages of conjugated equine oestrogen on the bone mineral density of postmenopausal Hong Kong Chinese women. DESIGN: A 1-year three-arm randomised controlled trial. SETTING: Out-patient setting at a governmental hospital in Hong Kong. PARTICIPANTS: One hundred and five women aged 45 years or older, in whom menopause had occurred not more than 2 years previously. INTERVENTION: Women were assigned randomly to treatment with conjugated equine oestrogen 0.625 mg/d or 0.3 mg/d, or no oestrogen. MAIN OUTCOME MEASURE: Bone mineral density. RESULTS: Women who were assigned to the control group showed a significant reduction in bone mineral density in both the femoral neck and the lumbar spine (3.6%; P=0.001 and 4.0%; P<0.001, respectively). Those who received oestrogen 0.3 mg/d showed a significant reduction (3.9%; P=0.010) and a non-significant reduction (2.2%; P=0.141) in their lumbar spine and femoral neck bone mineral densities, respectively. In contrast, there was little change in the spinal and femoral neck bone mineral densities in women who received estrogen 0.625 mg/d. CONCLUSION: The minimum effective dosage of conjugated equine oestrogen to prevent osteoporosis in postmenopausal Hong Kong Chinese women is 0.625 mg/d. The bone mineral density, however, was maintained but not increased.

Intersite comparison of the Hologic QDR-1000 dual energy X-ray bone densitometer.

UNLABELLED: We have compared results from 13 Hologic QDR-1000 bone densitometers: (i) by performing spine and hip scans on two normal volunteers; (ii) by acquiring sets of 10 sequential scans on a Hologic anthropomorphic spine phantom. For each QDR-1000 site visited a set of spine phantom scans was also acquired on a QDR-1000 at Guy's Hospital to serve as a control study. All scans were analysed using the Hologic scan comparison software. Radiographers at each site were asked to perform their own independent analysis of the scans of the two volunteers. The precision of the bone mineral density (BMD), bone mineral content (BMC) and projected area (Area) results for a set of 10 phantom scans was 0.11%, 0.14% and 0.12% respectively. The coefficient of variation (CV) between sites for the sets of phantom scans was 0.58% for BMD, 0.71% for BMC and 0.35% for Area. In comparison, CVs for the phantom scans acquired on a single QDR-1000 were 0.23%, 0.23% and 0.09% respectively. The CV for the BMD results on the two volunteers obtained using the scan comparison software averaged 1.4% for the spine and 2.1% for the femoral neck. The CV for the results obtained by site radiographers averaged 2.2% for the spine and 3.7% for the femoral neck. Significant differences in the technique used for hip analysis were found. CONCLUSIONS: (i) differences in calibration between systems were generally less than 1%; (ii) variations in results resulting from differences in analytical technique were more significant than those resulting from differences in calibration.

Role of bone scanning in detection of subclinical bone metastasis in nasopharyngeal carcinoma.

One hundred thirty-two new patients with nasopharyngeal carcinoma and no evidence of distant metastases were evaluated for bone metastases with bone scanning. Forty-four patients had abnormal hypercaptation. These abnormal findings were considered related to benign diseases in 39 patients after correlating clinical examinations and skeletal radiographs. The remaining five patients had positive bone scanning which was suggestive of bone metastasis. There were 13 patients who developed symptomatic bone metastases over a follow-up period of 0.2-41 months. In three of these, the bone metastases corresponded to the sites of abnormal hypercaptation in the initial positive bone scanning. In view of the low sensitivity and specificity of bone scanning in this setting, routine bone scanning for staging nasopharyngeal carcinoma is not recommended. But in the research setting, baseline scanning is useful to make subsequent scanning more valuable, and it reduces false-positive results.