A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy.

AIMS: To compare the respective performances of digital retinal imaging, fundus photography and slit-lamp biomicroscopy performed by trained optometrists, in screening for diabetic retinopathy. To assess the potential contribution of automated digital image analysis to a screening programme. METHODS: A group of 586 patients recruited from a diabetic clinic underwent three or four mydriatic screening methods for retinal examination. The respective performances of digital imaging (n=586; graded manually), colour slides (n=586; graded manually), and slit-lamp examination by specially trained optometrists (n=485), were evaluated against a reference standard of slit-lamp biomicroscopy by ophthalmologists with a special interest in medical retina. The performance of automated grading of the digital images by computer was also assessed. RESULTS: Slit-lamp examination by optometrists for referable diabetic retinopathy achieved a sensitivity of 73% (52-88) and a specificity of 90% (87-93). Using two-field imaging, manual grading of red-free digital images achieved a sensitivity of 93% (82-98) and a specificity of 87% (84-90), and for colour slides, a sensitivity of 96% (87-100) and a specificity of 89% (86-91). Almost identical results were achieved for both methods with single macular field imaging. Digital imaging had a lower technical failure rate (4.4% of patients) than colour slide photography (11.9%). Applying an automated grading protocol to the digital images detected any retinopathy, with a sensitivity of 83% (77-89) and a specificity of 71% (66-75) and diabetic macular oedema with a sensitivity of 76% (53-92) and a specificity of 85% (82-88). CONCLUSIONS: Both manual grading methods produced similar results whether using a one- or two-field protocol. Technical failures rates, and hence need for recall, were lower with digital imaging. One-field grading of fundus photographs appeared to be as effective as two-field. The optometrists achieved the lowest sensitivities but reported no technical failures. Automated grading of retinal images can improve efficiency of resource utilization in diabetic retinopathy screening.

An audit of the diagnostic usefulness of PRL and TSH responses to domperidone and high resolution magnetic resonance imaging of the pituitary in the evaluation of hyperprolactinaemia.

BACKGROUND AND OBJECTIVE: The usefulness of dynamic tests of PRL release in determining underlying pathology in hyperprolactinaemic patients is not well recognized by endocrinologists, only 15% of whom routinely perform such tests. High resolution pituitary magnetic resonance imaging (MRI) has become more widely available during the past 5 years and is now generally regarded as the pituitary imaging method of choice. Since few prolactinoma patients are now submitted to surgery, it is important to ascertain the usefulness of these techniques in suggesting a pathological diagnosis. DESIGN: A 3 year retrospective audit of the information derived from measurement of PRL and TSH responses to the dopamine antagonist domperidone and from high resolution pituitary MRI in patients being investigated for hyperprolactinemia in regional endocrine unit. PATIENTS: Eighty-four patients (10 male, 74 female) whose investigation of hyperprolactinaemia included a domperidone test and high resolution pituitary MRI. Patients who had domperidone tests performed after pituitary surgery or who did not have pituitary MRI were excluded from the analysis. MEASUREMENTS: PRL and TSH were measured basally and at 30 and 60 minutes following domperidone (10 mg i.v.) and gadolinium-enhanced pituitary MRI was performed in all patients. RESULTS: 20 patients had a normal PRL response to domperidone (defined as PRL30/PRL0 > 3) and this group included five patients in whom hyperprolactinaemia was not sustained. Pituitary MRI showed evidence of a microadenoma in only two patients, imaging being unequivocally normal in the majority. Sixty-four patients had an abnormal PRL response to domperidone and 18 of these had a macrolesion (nine prolactinomas, nine other tumours). Pituitary MRI was performed in the remaining 46 patients with abnormal PRL response to domperidone and suggested microadenoma in 29 (63%), identified other structural abnormalities in six cases but was entirely normal in 11 cases. Neither the basal PRL level nor the TSH response could refine the diagnosis further because of overlap between the various subgroups. CONCLUSIONS: The majority of patients with a normal dynamic response of PRL to domperidone had a normal or near normal pituitary MRI scan. In the two cases where an abnormality was detected it could have been an incidental microadenoma or cyst, thus suggesting that pituitary scanning could normally be omitted in patients whose PRL response to domperidone is normal (24% of our total). The group of patients with an abnormal dynamic response of PRL to domperidone was not generally amenable to further diagnostic refinement by considering the degree of hyperprolactinaemia or the TSH response to domperidone because of overlap of these parameters between the diagnostic subgroups. Therefore any degree of hyperprolactinaemia associated with a blunted PRL response to domperidone warrants pituitary imaging.