Standard threshold laser versus subthreshold micropulse laser for adults with diabetic macular oedema: the DIAMONDS non-inferiority RCT.

BACKGROUND: The National Institute for Health and Care Excellence recommends macular laser to treat diabetic macular oedema with a central retinal subfield thickness of < 400 µm on optical coherence tomography. The DIAMONDS (DIAbetic Macular Oedema aNd Diode Subthreshold micropulse laser) trial compared standard threshold macular laser with subthreshold micropulse laser to treat diabetic macular oedema suitable for macular laser. OBJECTIVES: Determining the clinical effectiveness, safety and cost-effectiveness of subthreshold micropulse laser compared with standard threshold macular laser to treat diabetic macular oedema with a central retinal subfield thickness of < 400 µm. DESIGN: A pragmatic, multicentre, allocation-concealed, double-masked, randomised, non-inferiority, clinical trial. SETTING: Hospital eye services in the UK. PARTICIPANTS: Adults with diabetes and centre-involving diabetic macular oedema with a central retinal subfield thickness of < 400 µm, and a visual acuity of > 24 Early Treatment Diabetic Retinopathy Study letters (Snellen equivalent > 20/320) in one/both eyes. INTERVENTIONS: Participants were randomised 1 : 1 to receive 577 nm subthreshold micropulse laser or standard threshold macular laser (e.g. argon laser, frequency-doubled neodymium-doped yttrium aluminium garnet 532 nm laser); laser treatments could be repeated as needed. Rescue therapy with intravitreal anti-vascular endothelial growth factor therapies or steroids was allowed if a loss of ≥ 10 Early Treatment Diabetic Retinopathy Study letters between visits occurred and/or central retinal subfield thickness increased to > 400 µm. MAIN OUTCOME MEASURES: The primary outcome was the mean change in best-corrected visual acuity in the study eye at 24 months (non-inferiority margin 5 Early Treatment Diabetic Retinopathy Study letters). Secondary outcomes included the mean change from baseline to 24 months in the following: binocular best-corrected visual acuity; central retinal subfield thickness; the mean deviation of the Humphrey 10-2 visual field in the study eye; the percentage of people meeting driving standards; and the EuroQol-5 Dimensions, five-level version, National Eye Institute Visual Function Questionnaire - 25 and Vision and Quality of Life Index scores. Other secondary outcomes were the cost per quality-adjusted life-years gained, adverse effects, number of laser treatments and additional rescue treatments. RESULTS: The DIAMONDS trial recruited fully (n = 266); 87% of participants in the subthreshold micropulse laser group and 86% of participants in the standard threshold macular laser group had primary outcome data. Groups were balanced regarding baseline characteristics. Mean best-corrected visual acuity change in the study eye from baseline to month 24 was -2.43 letters (standard deviation 8.20 letters) in the subthreshold micropulse laser group and -0.45 letters (standard deviation 6.72 letters) in the standard threshold macular laser group. Subthreshold micropulse laser was deemed to be not only non-inferior but also equivalent to standard threshold macular laser as the 95% confidence interval (-3.9 to -0.04 letters) lay wholly within both the upper and lower margins of the permitted maximum difference (5 Early Treatment Diabetic Retinopathy Study letters). There was no statistically significant difference between groups in any of the secondary outcomes investigated with the exception of the number of laser treatments performed, which was slightly higher in the subthreshold micropulse laser group (mean difference 0.48, 95% confidence interval 0.18 to 0.79; p = 0.002). Base-case analysis indicated no significant difference in the cost per quality-adjusted life-years between groups. FUTURE WORK: A trial in people with ≥ 400 µm diabetic macular oedema comparing anti-vascular endothelial growth factor therapy alone with anti-vascular endothelial growth factor therapy and macular laser applied at the time when central retinal subfield thickness has decreased to < 400 µm following anti-vascular endothelial growth factor injections would be of value because it could reduce the number of injections and, subsequently, costs and risks and inconvenience to patients. LIMITATIONS: The majority of participants enrolled had poorly controlled diabetes. CONCLUSIONS: Subthreshold micropulse laser was equivalent to standard threshold macular laser but required a slightly higher number of laser treatments. TRIAL REGISTRATION: This trial is registered as EudraCT 2015-001940-12, ISRCTN17742985 and NCT03690050. FUNDING: This project was funded by the National Institute for Health and Care Research ( NIHR ) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 50. See the NIHR Journals Library website for further project information.

The retina is a layer at the back of the eye. Its centre is called the macula and is responsible for central vision. Some people with diabetes develop diabetic macular oedema. In diabetic macular oedema fluid leaks from retinal blood vessels and builds up at the macula, resulting in sight loss. Diabetic macular oedema can be mild or severe; this can be determined measuring the thickness of the macula, which is measured in micrometres (µm). One micrometre is one thousandth of a millimetre. In mild diabetic macular oedema, the thickness of the macula increases, but is less than 400 µm. Patients with mild diabetic macular oedema can be treated with a laser and there are two laser types. The standard threshold macular laser has been available for many years. It clears the diabetic macular oedema but produces a 'burn' in the retina. The subthreshold micropulse laser is newer. It does not produce a burn but also clears the diabetic macular oedema. The lack of a burn, however, has led to doubts about whether or not this laser works as well as the standard threshold macular laser because 'no burn' was taken to mean 'less benefit'. These doubts led to our establishing the DIAMONDS (DIAbetic Macular Oedema aNd Diode Subthreshold micropulse laser) trial, which compared these two lasers for people with mild diabetic macular oedema. A total of 266 people suitable for either laser joined the study at 16 NHS hospitals across the UK; 133 received standard threshold macular laser and 133 received subthreshold micropulse laser. The choice of laser was determined by chance. The DIAMONDS trial found that the subthreshold micropulse laser was as good as the standard threshold macular laser (i.e. 'clinically equivalent') in terms of improving people's vision, reducing macula thickness, allowing people to meet driving standards and maintaining their quality of life, both in general terms and for vision in particular. There was a small increase (less than one session on average per person) in the number of laser treatment sessions needed with subthreshold micropulse laser. The costs of both laser treatments were about the same.

Cardiovascular assessment after treatment for retinopathy of prematurity: a comparative study between anti-VEGF agent (aflibercept) and laser.

OBJECTIVE: The aim of this study was to compare the cardiac effects and aortic arterial indices following intravitreal aflibercept treatment or diode laser photocoagulation for the treatment of retinopathy of prematurity (ROP) in infants. METHODS: This single-centre, retrospective study was conducted in infants who were administered laser photocoagulation (LPC) or intravitreal aflibercept (IVA) treatment as initial treatment and had completed at least one year of corrected age. The patients were evaluated in terms of aortic elastic parameters, right and left ventricular systolic and diastolic function using conventional, pulsed Doppler and tissue Doppler imaging (TDI) echocardiographic parameters. RESULTS: Fifteen infants were in the LPC group, 16 in the IVA group, and 20 in the control group. Although there were some statistically significant differences in terms of pulsed and TDI echocardiographic parameters between the treatment and control groups, these values could not clearly be adopted as a diastolic dysfunction and myocardial performance indices were not influenced. The aortic elastic parameters were impaired in both LPC and IVA groups compared to the control group. Consequently, we observed only minor differences between the treatment groups, which may suggest subtle changes due to the anti-angiogenic treatment. CONCLUSIONS: Although favourable and promising outcomes were obtained with intravitreal injection of anti-vascular endothelial growth factor agents for the treatment of ROP, concerns have been raised about potential systemic side effects, including potential cardiovascular side effects caused by these agents. The small reduction in right ventricular Doppler velocities could probably be explained by the use of anti-angiogenic or laser treatment in infants.

GreenLight Laser for benign prostatic hyperplasia.

PURPOSE OF REVIEW: GreenLight photoselective vaporization (GL-PV) is now established in the treatment of benign prostatic enlargement. The present review outlines the available technical armamentarium and summarizes the current best evidence on functional and safety outcomes. Moreover, future technical developments and refinements are presented. RECENT FINDINGS: GL-PV has evolved to be the most commonly performed procedure, second to conventional transurethral resection of the prostate (TURP) for surgical management of benign prostatic obstruction (BPO). On the basis of the data published in the randomized controlled Goliath study, GL-PV with 180-W technology is noninferior in terms of functional outcomes compared with TURP considering short and intermediate follow-up with a complication-free rate of around 80% after 24 months.The ongoing push towards high-power lasers can be explained by their more effective tissue ablative effect, leading to shorter operating times. Comparative analysis between high-power and low-power laser systems demonstrated similar retreatment rates and most institutions are, therefore, now performing 180-W GL-PV.Performed as an outpatient procedure, GL-PV is cost-effective with a low hospital re-admission rate. Plasma kinetic vaporization of the prostate (PKVP) has recently emerged as a potential contender in the field; also GreenLight enucleation of the prostate (GreenLEP) might be even more effective than GL-PV. SUMMARY: GL-PV appears to be a well tolerated surgical alternative for patients suffering from BPO. Long-term follow-up data from 120-W and 180-W laser systems are still pending. Potential competitors have recently been brought to the market and further trials and long-term data will show, whether GL-PV will stand the test of time. Regardless of technical specifications, surgeon's experience remains essential to achieve good functional and safety outcomes.

Therapies for macular edema associated with central retinal vein occlusion: a report by the American Academy of Ophthalmology.

PURPOSE: To review the available evidence regarding the safety and efficacy of therapies for the treatment of macular edema (ME) associated with central retinal vein occlusion (CRVO). METHODS: A literature search of the PubMed database was last conducted in March 2014 with no date restrictions but limited to articles published in English. A literature search of the Cochrane Library was also conducted in March 2014 with no date restrictions and without a language limitation. The combined searches yielded 108 citations, of which 20 were deemed clinically relevant for the Ophthalmic Technology Assessment Committee Retina/Vitreous panel to review in full text. Three additional studies were also identified for panel review. The level of evidence of these selected studies was reviewed by the panel methodologist. RESULTS: There were 7 citations representing 4 clinical trials that provided level I evidence supporting the use of anti-vascular endothelial growth factor (VEGF) pharmacotherapies for ME associated with CRVO, including intravitreal ranibizumab (2), aflibercept (3), and bevacizumab (2). There were 3 citations representing 2 studies with level I evidence for intravitreal corticosteroid injection with dexamethasone intravitreal implant (2 citations) or triamcinolone (1 citation), although cataract and glaucoma were observed in these studies. Level I evidence is available on the limited benefit of macular grid-pattern laser photocoagulation (1 citation). Eight other citations reviewed were rated as level II, and 4 citations were rated as level III. Long-term efficacy results (≥2 years of follow-up) are limited to intravitreal ranibizumab at this time, and few studies have evaluated combination therapy with anti-VEGF and corticosteroid versus monotherapy of either class of drug. CONCLUSIONS: Level I evidence indicates that intravitreal anti-VEGF pharmacotherapy is safe and effective over 2 years for ME associated with CRVO and that delay in treatment is associated with worse visual outcomes. In addition, level I evidence demonstrates short-term efficacy of intravitreal corticosteroid but also an association with a higher frequency of adverse events.

Assessment of laser induction of Bruch's membrane disruption in monkey by spectral-domain optical coherence tomography.

PURPOSE: Laser-induced choroidal neovascularisation is a widely used model for age-related macular degeneration. The success rates of induction have been relatively low in large animals such as monkeys. Our study aimed to investigate the laser-induced damages to the Bruch's membrane of monkeys using the spectral-domain optical coherence tomography (OCT). METHODS: Laser photocoagulation was performed in the posterior and peripheral fundus of a rhesus monkey using a 532 nm laser. The lesions were examined by fundus photography and spectral-domain OCT immediately after the procedure. Fluorescein angiography was performed after 3 and 4 weeks in the animal to assess the development of choroidal neovascularisation. RESULTS: A total of 44 lesions were produced in both eyes of the animal. Subretinal bubbles with or without haemorrhage were observed at 41 spots during the procedure. Spectral-domain OCT showed that laser damages varied considerably among lesions and the disruption of the Bruch's membrane could be visualised at 23 spots on the OCT images. Leakage of fluorescein was only observed after 3 and 4 weeks within the macular area at lesions where Bruch's membrane disruptions had been detected by OCT. CONCLUSIONS: The presence of subretinal bubbles with haemorrhage is not an accurate indicator for successful disruption of the Bruch's membrane. Instead, spectral-domain OCT provides a better alternative to assess the retinal damages to the Bruch's membrane during laser induction of choroidal neovascularisation in monkeys.

A United Kingdom-based economic evaluation of ranibizumab for patients with retinal vein occlusion (RVO).

OBJECTIVE: This study compares the cost-effectiveness of intravitreal ranibizumab vs observation and/or laser photocoagulation for treatment of macular edema secondary to retinal vein occlusion in a UK-based model. METHODS: A Markov model was constructed using transition probabilities and frequency of adverse events derived using data from the BRAVO, CRUISE, and HORIZON trials. Outcomes associated with treatments and health states were combined to predict overall health costs and outcomes for cohorts treated with each option. RESULTS: In branch retinal vein occlusion, ranibizumab produced a gain of 0.518 quality-adjusted life years at an incremental cost of £8141, compared with laser photocoagulation. The incremental cost-effectiveness ratio was £15,710 per quality-adjusted life year, and the incremental cost per month free from blindness was £658. In central retinal vein occlusion, ranibizumab produced a gain of 0.539 quality-adjusted life years at an incremental cost of £9216, compared with observation only. The incremental cost-effectiveness ratio was £17,103, and the incremental cost per month free from blindness was £423. CONCLUSIONS: These incremental cost-effectiveness ratios are below the £20,000-30,000 range typically accepted as a threshold for cost-effectiveness. This suggests that ranibizumab may be regarded as a cost-effective therapy for patients with macular edema secondary to retinal vein occlusion, relative to grid laser photocoagulation (for BRVO) and observation (for CRVO). Limitations include sparse data for utilities associated with the severity of visual impairment in the WSE in patients with RVO. A lack of direct comparative evidence between ranibizumab and the dexamethasone intravitreal implant for the treatment of BRVO and CRVO and the infeasibility of an indirect comparison due to significant heterogeneity in trial designs prevented the inclusion of this treatment as a comparator in the Markov model.

Randomized trial comparing endovenous laser ablation of the great saphenous vein with high ligation and stripping in patients with varicose veins: short-term results.

BACKGROUND: Endovenous laser (EVL) ablation of the great saphenous vein (GSV) is thought to minimize postoperative morbidity and reduce work loss compared with high ligation and stripping (HL/S). However, the procedures have not previously been compared in a randomized trial with parallel groups where both treatments were performed in tumescent anesthesia on an out-patient basis. METHODS: Patients with varicose veins due to GSV insufficiency were randomized to either EVL (980 nm) or HL/S in tumescent anesthesia. Miniphlebectomies were also performed. Patients were examined preoperatively and at 12 days, and 1, 3, and 6 months postoperatively. Sick leave, time to normal physical activity, pain score, use of analgesics, Aberdeen score, Medical Outcomes Study Short Form-36 quality-of-life score, Venous Clinical Severity Score (VCSS), and complication rates were investigated. The total cost of the procedures, including lost wages and equipment, was calculated. Cost calculations were based on the standard fee for HL/S with the addition of laser equipment and the standard salary and productivity level in Denmark. RESULTS: A follow-up of 6 months was achieved in 121 patients (137 legs). The groups were well matched for patient and GSV characteristics. Two HL/S procedures failed, and three GSVs recanalized in the EVL group. The groups experienced similar improvement in quality-of-life scores and VCSS score at 3 months. Only one patient in the HL/S group had a major complication, a wound infection that was treated successfully with antibiotics. The HL/S and EVL groups did not differ in mean time to resume normal physical activity (7.7 vs 6.9 calendar days) and work (7.6 vs 7.0 calendar days). Postoperative pain and bruising was higher in the HL/S group, but no difference in the use of analgesics was recorded. The total cost of the procedures, including lost wages, was euro 3084 ($3948 US) in the HL/S and euro 3396 ($4347 US) in the EVL group. CONCLUSIONS: This study suggests that the short-term efficacy and safety of EVL and HL/S are similar. Except for slightly increased postoperative pain and bruising in the HL/S group, no differences were found between the two treatment modalities. The treatments were equally safe and efficient in eliminating GSV reflux, alleviating symptoms and signs of GSV varicosities, and improving quality of life. Long-term outcomes, particularly with respect to recurrence rates, shall be investigated in future studies, including the continuation of the present.

A value-based medicine comparison of interventions for subfoveal neovascular macular degeneration.

OBJECTIVE: To perform a value-based medicine analysis of clinical trials that evaluate the interventions of laser photocoagulation, intravitreal pegaptanib therapy, and photodynamic therapy (PDT) with verteporfin for the treatment of classic subfoveal choroidal neovascularization. DESIGN: Reference case cost-utility analysis using value-based medicine principles, which use patient-based utility values and standardized, input variable criteria. PARTICIPANTS: Data from participants in the Macular Photocoagulation Study, Pegaptanib for Neovascular Age-Related Macular Degeneration Study, and the Treatment of Age-Related Macular Degeneration with Photodynamic Therapy Study. METHODS: Visual data were converted to a value-based format using time tradeoff utility analysis values from patients with macular degeneration. Costs were obtained from 2005 Medicare data. Outcomes (quality-adjusted life-years [QALYs]) and costs were discounted at a 3% annual rate. MAIN OUTCOME MEASURES: Interventional QALYs gained, percent improvement in quality of life, and dollars spent per QALY gained. RESULTS: Laser photocoagulation confers a 4.4% (P = 0.03 versus pegaptanib therapy) improvement in quality of life for the reference case, whereas pegaptanib therapy confers a 5.9% improvement and PDT confers an 8.1% (P = 0.0002 versus pegaptanib therapy) improvement. The cost-utility associated with laser photocoagulation is $8179, that for pegaptanib therapy is $66978, and that for PDT is $31544. All sensitivity analyses remain within the conventional standards of cost-effectiveness. CONCLUSIONS: Photodynamic therapy confers greater patient value than intravitreal pegaptanib therapy and laser photocoagulation for the treatment of classic subfoveal choroidal neovascularization. Despite the fact that laser photocoagulation is the most cost-effective intervention, both PDT and pegaptanib therapy deliver greater value, and thus are both preferred over laser photocoagulation. Using an economic measure, photodynamic therapy is the preferred treatment among these 3 interventions.

High-energy laser therapy of Barrett's esophagus: preliminary results.

We present the preliminary results obtained by our research group utilizing Nd:YAG and diode lasers to treat Barrett's esophagus (BE). A total of 15 patients with BE (mean age 58 years) underwent endoscopic laser therapy: 11 with intestinal metaplasia, 2 with low-grade dysplasia, and 2 with high-grade dysplasia. The mean length of BE was 4 cm (range 1-12 cm). Six of these patients also underwent antireflux surgery, and nine were prescribed acid-suppressive medication. Endoscopic Nd:YAG laser treatment was carried out from 1997 to 1999; thereafter, diode laser was employed. The mean follow-up of these patients after the first laser session was 28 months. Patients underwent a mean of 6.5 laser sessions (range 3-17 sessions), with no apparent complications. The mean energy per session was 1705 JJ. Only six of these patients (40%) showed complete endoscopic and histologic remission, but a mean of 77% (SD 23.8%) of the total metaplastic tissue in all these patients was ablated. The percentage of healed mucosa was higher in patients with short-segment BE (92%) ( p < 0.05) and in subjects treated by two or more laser sessions per centimeter of BE length (89%) ( p < 0.05). All four patients with dysplasia showed histologic regression to nondysplastic BE or to squamous epithelium, without recurrence during a mean follow-up of 30 months. The patients who underwent antireflux surgery and those prescribed pharmacologic treatment had similar results. Nd:YAG and diode laser treatment of BE is a safe, effective procedure; it required two sessions per centimeter of metaplasia; and it achieved complete regression of the dysplasia. Further studies are necessary to quantify its effect on cancer incidence.

Prostate laser operation--the cheapest therapy? 872 cases.

Prostate laser operation (PLO) is expensive; but without special fibres--that means f.i. NdYAG- or better Diode-laser--and simple reusable bare fibre it costs only about 20BEF/operation, 872 cases were operated in this way. Bare fibres enable a non-invasive but also invasive coagulation technique as well as an effective laser-cutting. High risk patients and patients under anticoagulation treatment are no contradiction against laser operation. The same laser can be used for many indications in urology--as cheap as in prostate therapy--besides in nearly all medical compartments interdisciplinary especially in smaller hospitals or outpatient therapy.

Video assisted thoracoscopic management of primary spontaneous pneumothorax.

Although Video-Assisted Thoracoscopic Surgery (VATS) is now accepted by many as the approach of choice in the management of primary spontaneous pneumothorax (PSP), the optimal procedure and the timing of surgical intervention remain areas of contention. The authors reviewed their combined experience with 518 consecutive VATS procedures for PSP in 483 patients. Mechanical pleurodesis was performed in every case and was the only procedure in 20 patients. We had experience with several means of eliminating subpleural bullae once identified: stapled bullectomy (196), endoloop (261), argon beam coagulation (6) and endoscopic suturing (35). There were no mortality or intraoperative complications. Median postoperative hospital stay was 3 days. So far, we have had 9 recurrences (1.74%), after a mean follow up of 20 months (range one to 36 months). Complications consisted of 18 persistent air leaks, 14 would infections and 1 chest wall bleeding. We conclude that (1) VATS is a safe and effective approach in the treatment of PSP; (2) Stapled-bullectomy is quick and reliable but costly; (3) Endoloop and suturing are viable alternative techniques that may prove to be more cost effective; (4) we do not recommend to use argon beam coagulation as the primary treatment modality.

Thermal damage assessment of blood vessels in a hamster skin flap model by fluorescence measurement of a liposome-dye system.

BACKGROUND AND OBJECTIVES: The present study was undertaken to evaluate the feasibility of thermal damage assessment of blood vessels by using laser-induced release of liposome-encapsulated dye. STUDY DESIGN/MATERIALS AND METHODS: Experiments were performed in a hamster skin flap model. Laser irradiation was achieved with a 300 microm fiber connected to a 805 nm diode laser (power = 0.8W, spot diameter = 1.3 mm and pulse exposure time lasting from 1 to 6 s) after potentiation using a specific indocyanine green (ICG) formulation (water and oil emulsion). Liposomes-encapsulated carboxyfluorescein were prepared by the sonication procedure. Carboxyfluorescein (5,6-CF) was loaded at high concentration (100 mM) in order to quench its fluorescence. The measurements were performed after i.v. injection of DSPC liposomes (1.5 ml) and lasted 40 min. Fluorescence emission was measured with an ultra high sensitivity intensified camera. RESULTS: Three different shapes of fluorescent spots were identified depending on target (blood vessel or skin) and energy deposition in tissue: (i) intravascular fluorescence, (ii) transient low fluorescence circular spot, and (iii) persistent high intense fluorescence spot. These images are correlated with histological data. CONCLUSION: Real-time fluorescence imaging seems to be a good tool to estimate in a non-invasive manner the thermal damage induced by a diode laser combined with ICG potentiation.

Lasers in rectosigmoid tumors.

Over a 14-year period, 746 patients were treated at the Lille Laser Center for rectosigmoid tumor. Two hundred seventy-two patients were treated for palliation of symptoms from rectosigmoid cancer and 474 patients were treated for a benign rectosigmoid villous adenoma. The immediate success rate and complication rate were 85% and 2%, respectively, for patients with advanced cancer, and 92.8% and 1.8% for those with a villous adenoma. Patients with an advanced cancer remained functionally improved during a 10.1-month average period after initial improvement. The recurrence rate after initial treatment for villous adenomas was 18% during a 29.7-month average follow-up. Immediate results were influenced by reason for treatment, initial symptoms, and circumferential extension for patients with a cancer, and only by circumferential extension for patients with a villous adenoma. Long-term results were influenced by reason for treatment and circumferential extension for patients with cancer, and by reason for treatment, initial histology and localization for patients with a villous adenoma. Laser treatment provided relief of symptoms in inoperable patients with advanced rectosigmoid carcinomas. Because treatment is long and difficult and the cancer rate is high, endoscopic laser should be limited in patients with a circumferential villous adenoma to non-surgical candidates. The risk of complication after surgery (some being fatal) has to be balanced against the risk of undetected carcinoma and the indication for endoscopic laser treatment should be discussed case by case.

Computed tomography-pathologic assessment of laser-induced necrosis in rat liver.

RATIONALE AND OBJECTIVES: Interstitial laser photocoagulation (ILP) causes localized tissue necrosis. This study was performed to determine 1) whether the changes seen on computed tomography (CT) correspond to the necrosis pathologically, and 2) which CT technique best shows the necrosis. METHODS: Eighteen Wistar rats had ILP to their liver using a neodymium yttrium aluminum garnet [Nd:YAG] laser. Radio-opaque markers attached to the liver defined an imaging plane. Precontrast "dynamic" and delayed CT scans were performed. The size of necrosis was measured on CT, and macroscopically after resecting the liver. Computed tomography density numbers were measured from the necrotic area and normal liver for each CT technique. RESULTS: There was a good correlation between the necrosis size on CT and pathologically (P < .001). Maximum lesion-to-liver contrast was obtained on "dynamic" CT scans. CONCLUSIONS: The extent of tissue density changes on CT in rat liver after ILP match the extent of necrosis seen pathologically. The best CT technique use assessed for evaluating laser-induced liver necrosis is dynamic contrast-enhanced scanning.