The carbon footprint and wastage of intravitreal injections.

PURPOSE: The healthcare system emits greenhouse gas emissions and produces waste that in turn threatens the health of populations. The objective of our study was to measure the ecological threat related to intravitreal injections. METHODS: Emissions were separated into scope 2 corresponding to Heating, Ventilation and Air Conditioning (HVAC) of the building, and scope 3 corresponding to travels (patients and staff), and life cycle assessment (LCA) of medical devices (MD) and pharmaceutics. Greenhouse gas (GHG) emissions and waste for a single injection were first measured through a waste audit, and secondly anticipated theoretically with a calculator. RESULTS: The average GHG emissions and waste measured were 277kgCO2eq/IVI and 0.5kg/IVI, respectively. Pharmaceuticals were responsible for 97% of total emissions. Emissions unrelated to pharmaceuticals counted for 8.4kgCO2eq/IVI. GHG emissions and waste estimated with the calculator were 276kgCO2eq/IVI and 0.5kg/IVI, respectively, showing that the calculator was accurate. CONCLUSION: Our study provides a puzzle piece to carbon footprint and waste assessment in the field of ophthalmology. It may help provide concrete data for future green vs. vision discussions.

High intensity focused ultrasound cyclodestruction versus cyclodiode treatment of refractory glaucoma: A retrospective comparative study.

PURPOSE: To compare the efficacy of two cyclodestructive treatments for refractory glaucoma: High Intensity Focused Ultrasound (HIFU) cyclocoagulation and transscleral diode laser cyclophotocoagulation (cyclodiode). METHODS: A retrospective comparative single centre study including all patients who underwent cyclodestruction for refractory glaucoma by either HIFU cyclocoagulation or cyclodiode. "Refractory glaucoma" was defined as an uncontrolled high IOP despite medical treatment and at least one filtering surgery. Uncontrolled high IOP was defined as an IOP≥16mm Hg. The diagnosis of glaucoma was confirmed by automated visual field (VF) testing and peripapillary RNFL scans using a time-domain ocular coherence tomography device. Treatment success was defined as: postoperative IOP between 5mm Hg and 21mm Hg and IOP reduction greater than or equal to 20% as compared to preoperative values. RESULTS: Among the 99 eyes of 86 patients included in this study, 29 eyes were treated by cyclodiode and 70 eyes by HIFU. Median follow-up was 3 months (IQR 3-6) for the cyclodiode group and 6 months (IQR 3-8) for the HIFU group. Average preoperative intraocular pressure (IOP) was 34.3±11.1mm Hg (cyclodiode group) and 23±6.8mm Hg (HIFU group). The treatment success rate at last follow-up was 52% [34-70] for the cyclodiode group and 25% [15-35] for the HIFU group (P value=0.01). Kaplan-Meier survival analysis showed that the mean estimated time to failure was 5.9 months (4.4-7.5) for the cyclodiode group and 3.7 months (2.8-4.7) for the HIFU group (log-Rank test, P=0.02). A 2-line visual acuity loss was observed for 31% of the patients treated by cyclodiode and 17% for those treated by HIFU. In the cyclodiode group 4 cases of hypotony were reported vs. none in the HIFU group. CONCLUSIONS: The success rate was significantly higher for cyclodiode treatment as compared to HIFU cyclodestruction when treating refractory glaucoma. However, significantly fewer complications were observed with HIFU cyclocoagulation as compared to cyclodiode.

Familial retinoblastoma: fundus screening schedule impact and guideline proposal. A retrospective study.

AIMS: To assess if systematic fundus screening according to an 'intensive' schedule alters ocular outcome and to propose fundus screening schedule guidelines for children related to a retinoblastoma patient. METHODS: For children with a positive family history of retinoblastoma, we perform fundus exams shortly after birth under general anaesthesia and then at regular intervals according to schedules based on the risk. Familial retinoblastoma cases seen at our institution from January 1995 to December 2004 were retrospectively classified as 'screened' or 'non-screened' (NS) and, among the 'screened' patients, as 'intensively screened' (IS) if screening matched our recommendations or 'non-intensively screened' (S). Groups were compared by Fisher exact test for categorical variables and Kruskal-Wallis test for continuous variables. RESULTS: Among the 547 retinoblastoma patients managed at our institution during this period, 59 were familial cases. In all, 20 were in the NS group, 23 in the S group, and 16 in the IS group. The number of children enucleated was, respectively, 13, 2, and 0 (P<10(-4)); external beam radiation (EBRT) was required for, respectively, 6, 0, and 2 children (P<0.009). Chemotherapy burden and visual acuity were not significantly different between groups. CONCLUSION: An 'intensive' fundus screening schedule decreased the need for enucleation and EBRT. Therefore, despite the heavy burden of the screening schedule, we recommend physicians and health-care professionals to better inform and refer children with a family history of retinoblastoma for genetic counselling and proper fundus screening in specialized centres.

Impact of section doubling on lesion contrast.

Misregistration between section position and a feature of interest, such as a lesion, can result in loss of contrast on magnetic resonance images. Because the section direction typically has the poorest resolution, reduction of section misregistration can improve lesion contrast. Lesions occur at random sites; hence, to reduce misregistration, it is necessary to repeat imaging with a small amount of offset. This is impractical. Therefore, a reconstruction algorithm that yields offset sections was implemented, in which sections were produced with a zero- and a half-section shift. This algorithm was tested in 14 patients with multiple sclerosis. As expected, because of randomness associated with section placement relative to lesions, the half-shifted sections provided greater contrast as often as the zero-shifted sections. The combined set improved contrast significantly in 39% of lesions; improvement was greatest in lesions with lesser contrast. Signal-to-noise ratios were not affected by this process, which appears to be useful in magnetic resonance image reconstruction.

Magnetic resonance imaging characteristics of multiple sclerosis plaques imaged with two-dimensional and three-dimensional Fourier transform techniques at low and mid field strengths.

A total of 58 multiple sclerosis lesions from 16 patients were used to characterize the performance of a low field system for the detection of edematous (e.g., water-elevating) brain lesions. Contrast, signal-to-noise, and their product (signal difference to noise) were measured for two-dimensional and three-dimensional Fourier transform techniques at low field strength (640 G) and compared to two-dimensional sequences at mid field strength (3,500 G). The results showed numerically that low-field strength magnetic resonance imaging can reliably detect multiple sclerosis lesions, and, by extension, other water-elevating lesions, although with lower confidence levels.

Low-field 3-DFT MRI: conceptual, analytical, and experimental aspects.

Three-dimensional Fourier transform (3-DFT) magnetic resonance imaging (MRI) offers advantages in terms of signal-to-noise (S/N) per unit of time for the case where a large number of slices is desired. This advantage is enhanced when the relaxation time, T(1 ), is short. Because time limitations in 3-DFT imaging force the use of short time intervals, TR, between excitations of a slice, lesion contrast is often undesirable at mid-and high-field strength even when the S/N is good. At low fields, where T(1) values are short, high S/N and contrast can both be achieved with 3-DFT MR images. The conceptual and analytical aspects of low-field 3-DFT MRI are presented and demonstrated at 640 G.

MR imaging of excessively obese patients: the use of an open permanent magnet.

Excessive obesity can pose a limitation to both clinical and radiographic evaluation. Although CT and MR have revolutionized head and body imaging, patients with weights above 300 lb present a restriction of these imaging modalities. Magnetic resonance imaging (MRI) is well suited for imaging excessively obese patients, because the RF used does not have difficulty in penetrating large amounts of adipose tissue as ionizing radiation or sound waves does. The limitations of conventional MR imaging in these obese patients are the gantry size and the table weight limit. The recent development of a new low field MR imager with a larger gantry size and greater weight capacity, has the potential for imaging obese patients that cannot be evaluated by standard CT or MR. In this paper, we report our experience in imaging nine excessively obese patients with weights between 350 and 490 lb using a permanent magnet operating at 0.064 T.

MR imaging of the knee with a 0.064-T permanent magnet.

Magnetic resonance (MR) imaging has proved beneficial in the evaluation of internal derangements of the knee. A limitation to general acceptance of MR imaging of the knee has been availability and cost. The recent introduction of low-field-strength MR imaging has shown promise in decreasing the cost and increasing the availability of this modality. High-resolution (pixel size, 0.7 mm2), three-dimensional Fourier transform (3DFT), thin-section (3.5 mm) imaging performed on a 0.064-T permanent magnet was used to evaluate 117 knees in 114 consecutive patients. The appearance of normal anatomy and internal derangements of the knee at low-field-strength imaging is described. Arthroscopic correlation was available for 28 knees. Findings from low-field-strength MR imaging and arthroscopy agreed in 79% of cases in the determination of meniscal tears. Partial-flip-angle techniques with 3DFT produced thin-section images of the knee of diagnostic quality. The authors conclude that in patients with internal derangements of the knee, low-field-strength (0.064-T) MR imaging may provide useful information.

Accessible magnetic resonance imaging.

The cost of magnetic resonance imaging (MRI) is driven by magnetic field strength. Misperceptions as to the impact of field strength on performance have led to systems that are more expensive than they need to be. Careful analysis of all the factors that affect diagnostic quality lead to the conclusion that field strength per se is not a strong determinant of system performance. Freed from the constraints imposed by high-field operation, it is possible to exploit a varied set of opportunities afforded by low-field operation. In addition to lower costs and easier siting, we can take advantage of shortened T1 times, higher contrast, reduced sensitivity to motion, and reduced radiofrequency power deposition. These conceptual advantages can be made to coalesce onto practical imaging systems. We describe a low-cost MRI system that utilizes a permanent magnet of open design. Careful optimization of receiving antennas and acquisition sequences permit performance levels consistent with those needed for an effective diagnostic unit. Ancillary advantages include easy access to the patient, reduced claustrophobia, quiet and comfortable operation, and absence of a missile effect. The system can be sited in 350 sq ft and consumes a modest amount of electricity. MRI equipment of this kind can widen the population base than can access this powerful and beneficial diagnostic modality.

Film-screen mammography x-ray tube anodes: molybdenum versus tungsten.

Gridless screen-film mammography at 23 kVp with a W anode (inherent filtration: 0.1 mm A1, added filtration: 0.025 mm Mo) can achieve contrast identical to that achieved with gridless film-screen mammography at 27 kVp with a Mo anode (inherent filtration: 1.0 mm Be, added filtration: 0.025-mm Mo). However, W-anode film-screen mammograms obtained at 23 kVp require more radiation than Mo-anode film-screen mammograms obtained at 27 kVp. The lack of contrast of W-anode film-screen images produced at the same kVp as Mo-anode images was verified clinically and with a low contrast test object imaged over a range of densities. A step wedge test object was then used to match contrast between Mo- and W-anode gridless film-screen images at various kVp. The low contrast test object images verified the contrast equivalence of images obtained at 23 kVp for a W anode and 27 kVp for a Mo anode. A comparison of the two kVp for different anode materials was tested clinically on ten patients. The clinical and low contrast test object experiments were reviewed by three radiologists specializing in mammography.

[New possibilities and aspects of low-field magnetic resonance tomography]. / Neue Möglichkeiten und Gesichtspunkte der Low-Field-Kernspintomographie.

Worldwide, MRI is going up to higher field-strength. For imaging, magnets with field-strength between 0.2 and about 2.5 Tesla are installed. Below 0.2 Tesla, Low-Field-systems have been used in research-projects to optimize image quality. New developments of 0.064 Tesla Permanent-Magnet-MRI are hopeful for clinical work. Future possibilities of Low-Field-MRI are shown. The advantages of this system are good image quality by low initial start-up and operating costs as well as ease of sitting and lack of need for cryogens. The open design has excellent patient acceptance and allows to examine patients with claustrophobia feelings. It allows easier monitoring during the examination-especially children and patients with cancer or polytraumatic diseases. The introduction of more affordable MRI-systems of low-field-strength may decrease the cost of MRI to the point where it is competitive with computer tomography.

Mammographic film-processor temperature, development time, and chemistry: effect on dose, contrast, and noise.

Six different combinations of film-processor temperature (33.3 degrees C, 35 degrees C), development time (22 sec, 44 sec), and chemistry (Du Pont medium contrast developer [MCD] and Kodak rapid process [RP] developer) were each evaluated by separate analyses with Hurter and Driffield curves, test images of plastic step wedges, noise variance analysis, and phantom images; each combination also was evaluated clinically. Du Pont MCD chemistry produced greater contrast than did Kodak RP chemistry. A change in temperature from 33.3 degrees C (92 degrees F) to 35 degrees C (95 degrees F) had the least effect on dose and image contrast. Temperatures of 36.7 degrees C (98 degrees F) and 38.3 degrees C (101 degrees F) also were tested with extended processing. The speed increased for 36.7 degrees C but decreased at 38.3 degrees C. Base plus fog increased, but contrast decreased for these higher temperatures. Increasing development time had the greatest effect on decreasing the dose required for equivalent film darkening when imaging BR12 breast equivalent test objects; ion chamber measurements showed a 32% reduction in dose when the development time was increased from 22 to 44 sec. Although noise variance doubled in images processed with the extended development time, diagnostic capability was not compromised. Extending the processing time for mammographic films was an effective method of dose reduction, whereas varying the processing temperature and chemicals had less effect on contrast and dose.