A perspective on medical infrared imaging.

Since the early days of thermography in the 1950s, image processing techniques, sensitivity of thermal sensors and spatial resolution have progressed greatly, holding out fresh promise for infrared (IR) imaging techniques. Applications in civil, industrial and healthcare fields are thus reaching a high level of technical performance. The relationship between body temperature and disease was documented since 400 bc. In many diseases there are variations in blood flow, and these in turn affect the skin temperature. IR imaging offers a useful and non-invasive approach to the diagnosis and treatment (as therapeutic aids) of many disorders, in particular in the areas of rheumatology, dermatology, orthopaedics and circulatory abnormalities. This paper reviews many usages (and hence the limitations) of thermography in biomedical fields.

Multiplex polymerase chain reaction for diagnosis of viral and chlamydial keratoconjunctivitis.

PURPOSE: To develop a multiplex polymerase chain reaction (PCR) for the detection of adenovirus, herpes simplex virus, and Chlamydia trachomatis in conjunctival swabs. METHODS: Oligonucleotide primers for detection of the 3 agents were combined in one reaction and evaluated for optimal performance using control DNAs of adenovirus type 2, herpes simplex virus, and C. trachomatis plasmid. The multiplex PCR was evaluated prospectively against its corresponding uniplex PCRs, virus isolation, Chlamydia Amplicor PCR, and an immunoassay technique (immune dot blot test) in a total of 805 conjunctival swabs from patients with suspected viral and chlamydial keratoconjunctivitis. RESULTS: The multiplex PCR was as sensitive as uniplex PCRs for the detection of the agents in clinical specimens. In the prospective study, 48 of 49 (98%) clinical specimens were positive for adenovirus by the multiplex PCR compared with 26 of 49 (53%) by adenovirus isolation. For herpes simplex virus detection, the multiplex PCR had a sensitivity of 92% (34/37) compared with 94.5% (35/37) by cell culture. The multiplex PCR produced identical results to the Amplicor PCR (21/21; 100%) compared with 71% (15/21) by the immune dot blot test. CONCLUSIONS: With clinical specimens the multiplex PCR was as sensitive as its respective uniplex PCRs but more sensitive than adenovirus isolation and as sensitive as herpes simplex virus isolation or C. trachomatis Amplicor PCR. It has the potential to replace several diagnostic tests with consequent savings in cost. The test also reduces the risk of misdiagnosis by the clinicians.

Adenovirus polymerase chain reaction assay for rapid diagnosis of conjunctivitis.

PURPOSE: To evaluate newly designed primers in a polymerase chain reaction (PCR) for the detection of adenovirus DNA in conjunctival swabs. METHODS: Oligonucleotides were derived from the adenovirus hexon gene and modified such that a maximum of only two mismatches occurred with adenovirus types 2 through 5, 7, and 16. Specificity was determined against adenovirus types 2 through 4, 7, 8 through 11, 14, 19, 37, 40, and 41 and from non-adenoviral DNA and the sensitivity by PCR amplification of purified adenovirus type 2 DNA. The assay was compared retrospectively with cell culture and a PCR with different primers on 59 stored conjunctival swab samples. The new PCR also was used prospectively in comparison with cell culture on 2743 conjunctival swabs. RESULTS: The 140-bp product was amplified from all the adenovirus serotypes tested except types 40 and 41, which have not been isolated from the eye. There were no amplified products from the non-adenoviral DNA tested. With adenovirus type 2 DNA, despite two deliberate mismatches, 40 copies of the target were detectable after PCR and ethidium bromide-staining. In the retrospective study, 51 of 55 (92.7%) were positive by this new PCR compared with 42 of 55 (76.4%) by the older PCR and 40 of 55 (72.7%) by cell culture. In the prospective study, the new PCR detected 386 of 415 (93%) adenovirus-positive specimens compared with 248 of 415 (59.8%) by cell culture. Of 167 specimens positive for herpes simplex virus by cell culture, none were positive by the adenovirus PCR. CONCLUSIONS: PCR with the newly designed primers shows a much increased sensitivity over cell culture and previous PCRs for the detection of adenoviruses in conjunctival swabs.

Effect of various infection-control methods for light-cure units on the cure of composite resins.

This study (1) compared the curing-light intensity with various barrier infection-control methods used to prevent cross contamination, (2) compared the Knoop hardness value of cured composite resin when various barrier control methods were used, and (3) correlated the hardness of the composite resin with the light-intensity output when different infection-control methods were used. The light-cure unit tips were covered with barriers, such as cellophane wrap, plastic gloves, Steri-shields, and finger cots. The control group had no barrier. Composite resins were then cured for each of the five groups, and their Knoop hardness values recorded. The results showed that there was significant statistical difference in the light-intensity output among the five groups. However, there was no significant statistical difference in the Knoop hardness values among any of the groups. There was also no correlation between the Knoop hardness value of the composite resin with the light-intensity output and the different infection-control methods. Therefore, any of the five infection-control methods could be used as barriers for preventing cross-contamination of the light-cure unit tip, for the light-intensity output for all five groups exceeded the recommended value of 300 W/m2. However, to allow a greater margin of error in clinical situations, the authors recommend that the plastic glove or the cellophane wrap be used to wrap the light-cure tip, since these barriers allowed the highest light-intensity output.