PET/CT imaging: detection of choroidal melanoma.

AIM: To determine the size of untreated choroidal melanomas resolved by whole body positron emission tomography fused with computed tomography (PET/CT). METHODS: 50 consecutive patients with untreated choroidal melanomas underwent whole body PET/CT. A functionally fused helical CT scan and 18-fluoro-2-deoxyglucose (FDG) PET scans were employed. The tumours were identified (both quantitatively and qualitatively) and compared with clinical measurements derived from ophthalmoscopic, angiographic, and ultrasonographic imaging. Standardised uptake values (SUV) of more than 2.5 were considered positive. RESULTS: Among the 50 patients with choroidal melanoma, PET/CT scan SUVs of more than 2.5 were noted in 14 (28%) tumours. No AJCC T1 class tumours, 33.3% of T2 melanomas, and 75% of T3 melanomas were physiologically identifiable on PET/CT. With respect to COMS group classifications, no small choroidal tumours, 33% of medium, and 75% of large melanomas were physiologically identifiable. The sole ring melanoma was identifiable on PET/CT imaging. The smallest tumour physiologically identifiable by PET/CT had basal dimensions of 3x5.9 and an apical height of 2.9 mm. CONCLUSION: Though PET/CT was found to be capable of physiologically identifying certain medium (T2) and most large sized (T3) choroidal melanomas, physiological imaging was not completely dependent upon tumour size. Functionally fused PET/CT localised the tumours within the eye and assessed their physiological activity.

Whole body PET/CT for initial staging of choroidal melanoma.

AIM: To investigate the value of whole body positron emission tomography/computed tomography (PET/CT) in screening for metastatic choroidal melanoma in patients initially diagnosed with choroidal melanoma. METHODS: 52 patients with choroidal melanoma underwent whole body PET/CT as part of their metastatic investigation. PET/CT scans were used as a screening tool at the time of their initial diagnosis. A physical examination, liver function tests, and a baseline chest x ray were also obtained. PET/CT images (utilising intravenous18-fluoro-2-deoxyglucose (FDG)) were studied for the presence of metastatic melanoma. The standards for reference were further imaging and/or subsequent biopsies. RESULTS: Two of 52 (3.8%) patients were found to have metastatic melanoma before treatment. The most common sites for metastases were the liver (100%), bone (50%), and lymph nodes (50%). Brain involvement was also present in one patient. One patient (50%) had involvement of multiple sites. Haematological liver enzyme assays were normal in both patients. PET/CT showed false positive results in three patients (5.7%) when further evaluated by histopathology and/or additional imaging. In seven patients (13.4%) PET/CT imaging detected benign lesions in the bone, lung, lymph nodes, colon, and rectum. CONCLUSION: PET/CT imaging can be used as a screening tool for the detection and localisation of metastatic choroidal melanoma. Liver enzyme assays did not identify liver metastases, while PET/CT revealed both hepatic and extrahepatic metastatic melanoma. PET/CT imaging may improve upon the conventional methods of screening for detection of metastatic disease in patients initially diagnosed with choroidal melanoma.

Modern external beam radiation therapy for refractory dissecting cellulitis of the scalp.

BACKGROUND: Dissecting cellulitis of the scalp can be an extremely painful and disfiguring dermatological condition. The associated pain can be severe enough in some cases to require opioid analgesics, and this pain in conjunction with the disfigurement can induce significant emotional distress. Conservative treatments often fail to provide relief. Radiation therapy has been successfully used in the past but with outdated equipment and techniques. OBJECTIVES: To evaluate the efficacy and toxicity of modern external beam radiation therapy techniques for the treatment of dissecting cellulitis of the scalp. METHODS: Four patients with intractable dissecting cellulitis of the scalp were treated with electrons or a combination of electrons and photons to the entire scalp. Daily fraction sizes were 2.5 or 3 Gy and initially prescribed to 15-21 Gy. Patients were re-evaluated 3-4 weeks after completion of therapy. Any residual hair growth was treated with additional radiation treatments to ensure full epilation, up to a maximum dose of 35 Gy. RESULTS: Rapid resolution of pain was seen in all patients with pain. Regression of nodules and decreased discharge was seen in all patients following treatment and cosmesis was subjectively improved. No long-term toxicity has been observed. CONCLUSIONS: Using modern techniques and equipment, radiation therapy appears to be a reasonable option for patients with severe/refractory dissecting cellulitis of the scalp. Acute effects are mild and well tolerated. Aside from alopecia, which was present to some extent in all patients before treatment, no long-term complications have been observed.

Spermicide permeation through biocompatible polymers.

Although spermicides are safe and effective contraceptive/prophylactic agents, they are inconvenient to use. Formulations that provide a controlled release of spermicide may improve user acceptance, and therefore effectiveness. Using a two-chamber diffusion cell, we measured the rates of permeation of nonoxynol-9 (N9), benzalkonium chloride (BC), and chlorhexidine (CH) through films of ethylene-vinyl acetate copolymer (EVAc) and silicone elastomer (SILASTIC). In addition, we encapsulated N9, BC, and CH into solid polymer matrices and measured the rate of spermicide release following immersion in water. We also developed equations for predicting the release rate of spermicide from a vaginal ring containing encapsulated spermicide, and tested these equations using hollow SILASTIC rings containing pure N9 or BC. N9 diffuses through a thin film of SILASTIC several orders of magnitude slower than through water. The rates of permeation of N9 through EVAc, BC through SILASTIC, and CH through SILASTIC were too low to detect over a one-week experiment. Polymer matrices of EVAc or SILASTIC released N9 at a controlled rate for several days. Based on these measurements, we predict that a vaginal ring containing an inner core of EVAc/N9 surrounded by a thin, permeable layer of SILASTIC will provide a controlled, constant release of N9 for over 30 days. Because of its low permeability in SILASTIC, BC is probably not a good spermicide for a long-acting vaginal ring. Because of its low solubility in water, CH is also not a good candidate for controlled release into the vaginal mucus.