qPET - a quantitative extension of the Deauville scale to assess response in interim FDG-PET scans in lymphoma

BACKGROUND

Interim FDG-PET is used for treatment tailoring in lymphoma. Deauville response criteria consist of five ordinal categories based on visual comparison of residual tumor uptake to physiological reference uptakes. However, PET-response is a continuum and visual assessments can be distorted by optical illusions.

OBJECTIVES

With a novel semi-automatic quantification tool we eliminate optical illusions and extend the Deauville score to a continuous scale.

PATIENTS AND METHODS

SUVpeak of residual tumors and average uptake of the liver is measured with standardized volumes of interest. The qPET value is the quotient of these measurements. Deauville scores and qPET-values were determined in 898 pediatric Hodgkin's lymphoma patients after two OEPA chemotherapy cycles.

RESULTS

Deauville categories translate to thresholds on the qPET scale: Categories 3, 4, 5 correspond to qPET values of 0.95, 1.3 and 2.0, respectively. The distribution of qPET values is unimodal with a peak representing metabolically normal responses and a tail of clearly abnormal outliers. In our patients, the peak is at qPET = 0.95 coinciding with the border between Deauville 2 and 3. qPET cut values of 1.3 or 2 (determined by fitting mixture models) select abnormal metabolic responses with high sensitivity, respectively, specificity.

CONCLUSIONS

qPET methodology provides semi-automatic quantification for interim FDG-PET response in lymphoma extending ordinal Deauville scoring to a continuous scale. Deauville categories correspond to certain qPET cut values. Thresholds between normal and abnormal response can be derived from the qPET-distribution without need for follow-up data. In our patients, qPET < 1.3 excludes abnormal response with high sensitivity.

Anosognosia in very mild Alzheimer's disease but not in mild cognitive impairment

OBJECTIVE

To study awareness of cognitive dysfunction in patients with very mild Alzheimer's disease (AD) and subjects with mild cognitive impairment (MCI).

METHODS

A complaint interview covering 13 cognitive domains was administered to 82 AD and 79 MCI patients and their caregivers. The patient groups were comparable according to age and education, and Mini Mental State Examination (MMSE) scores were > or =24 in all cases. The discrepancy between the patients' and caregivers' estimations of impairments was taken as a measure of anosognosia.

RESULTS

Self-reports of cognitive difficulties were comparable for AD and MCI patients. However, while in comparison to caregivers MCI patients reported significantly more cognitive impairment (p < 0.05), AD patients complained significantly less cognitive dysfunctions (p < 0.001).

CONCLUSIONS

While most MCI patients tend to overestimate cognitive deficits when compared to their caregiver's assessment, AD patients in early stages of disease underestimate cognitive dysfunctions. Anosognosia can thus be regarded as a characteristic symptom at a stage of very mild AD (MMSE > or =24) but not MCI. Accordingly, medical history even in mildly affected patients should always include information from both patient and caregiver.

Synthetic as compared with natural vitamin E is preferentially excreted as alpha-CEHC in human urine: studies using deuterated alpha-tocopheryl acetates

Alpha-CEHC (2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman) is a urinary vitamin E metabolite with a truncated phytyl tail. To test whether natural and synthetic vitamin E are similarly converted to alpha-CEHC, 6 humans consumed 150 mg each RRR-alpha-[5-(C2H3)]- and all rac-alpha-[5,7(C2H3)2]-tocopheryl acetates (d3RRR-alpha- and d6all rac-alpha-tocopheryl acetates, respectively). Plasma was collected at 0, 6, 12 and 24 h; urine (24 h) at 0, 1, 2, 3, 4 and 8 days. Following dosing, plasma was enriched with d3RRR-alpha-tocopherol, while urine was enriched with alpha-CEHC derived from d6all rac-alpha-tocopherol. Thus, synthetic compared with natural vitamin E is preferentially metabolized to alpha-CEHC and excreted.

The effect of three-component total ankle replacement malalignment on clinical outcome: pain relief and functional outcome in 317 consecutive patients

BACKGROUND

Total ankle replacement has become an increasingly popular treatment for patients with end-stage ankle osteoarthritis. The surgery is technically demanding and generally performed by only experienced foot and ankle surgeons. An important complication of total ankle replacement is malposition of the talar component. The biomechanical effect of malposition has been reported; however, the functional outcomes of patients with varying degrees of talar component malposition have not. The purpose of this study was to assess the influence of talar component malposition on postoperative pain relief and functional outcome.

METHODS

This retrospective cohort study included 317 total ankle replacements in 317 patients. The anteroposterior offset ratio was measured with use of lateral ankle radiographs made with the patient in a standing, weight-bearing position. Patients were classified into one of three groups: those with an anteroposterior offset ratio of 0 (127 ankles), those with a ratio of >0 (103 ankles), and those with a ratio of <0 (eighty-seven ankles). Postoperative pain relief was assessed with use of a visual analogue scale. Functional outcome was assessed with the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score and measurement of ankle range of motion. The mean duration of follow-up (and standard deviation) was 53.2 ± 18.4 months (range, twenty-four to ninety-eight months).

RESULTS

The postoperative pain level in the group with an anteroposterior offset ratio of 0 was significantly lower than that for both the group with a ratio of >0 (p < 0.001) and the group with a ratio of <0 (p = 0.017). Also, the functional outcome, measured with use of the AOFAS hindfoot score, was significantly higher, and ankle motion was significantly greater, in the group with an anteroposterior offset ratio of 0 than in the group with a ratio of >0 (p = 0.003 and p < 0.001, respectively) and the group with a ratio of <0 (p = 0.007 and p = 0.080).

CONCLUSIONS

The anteroposterior offset ratio may be a useful predictor of outcome in patients with total ankle replacement with regard to both pain and function.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Anatomy of the clavicle and the intramedullary nailing of midclavicular fractures

Intramedullary fixation is used increasingly to treat clavicular fractures. Anatomical variations in the clavicle of relevance to this procedure are analyzed. The length, diameters and curvature of the clavicle were measured in 196 specimens from the dissecting room. The calcium bone density was analyzed in 300 cross-sectional samples of 100 specimens. The thickness of cortical and medullary bone of 70 slices was analyzed from freshly plastinated clavicles with implants in place. The female clavicle was shorter, less curved, and had a lower concentration of calcium than the male clavicle. Measurement of cortical thickness showed a mean value of 1.05 +/- 0.23 mm at the most sternal measuring point, 2.05 +/- 0.29 mm at the midpoint of the clavicle, and 0.95 +/- 0.35 mm at the acromial end. The thinnest regions were the medial ventral cortex and the dorsal acromial cortex. These measurements explain clinical observations on nail perforation. The diameter of the medullary canal measured 6.7 +/- 2.6 mm at its narrowest part, so that reaming (i.e., predrilling the medullary canal) prior to 3.5 mm titanium nail insertion is not necessary. The main difficulties encountered when placing a nail are secondary to the S-curvature of the clavicle. In 80% of fractures, the break is located at the narrowest diameter of the medullary canal. Thus, the clavicle displays definite gender- and side-specific anatomical features in terms of length, diameter, curvature, and calcium concentration. These should be considered when performing intramedullary fixation.

Insert position in three-component total ankle replacement

BACKGROUND

Total ankle replacement has become a valuable treatment option for end-stage osteoarthritis. The most recent generation of implants comprises a second interface between the polyethylene insert and the tibial prosthetic component. This may permit a better adaptation of position between the implant components and thereby prevent unphysiological loading of ankle ligaments and reduce polyethylene wear. To date, no available data have evaluated whether the relative position of talar and tibial implant components change over time.

MATERIALS AND METHODS

We assessed the radiographs of 368 ankles that underwent primary arthroplasty with a HINTEGRA® (Newdeal SA, Lyon, France / Integra, Plainsboro, NJ) ankle to determine the spatial relationship between talar and tibial components at the time of surgery and during followup. The mean time to final followup was 51.2 months (range 11 to 98). We analyzed the anteroposterior offset as the distance between the center of the tibiotalar joint and the longitudinal axis of the tibia.

RESULTS

The mean anteroposterior offset ratio was 0.0 ± 0.06 (range -0.21 to 0.16), and it remained constant over time.

CONCLUSION

Our data suggest that the latest three-component prosthesis functions similar to the two-component prosthesis, but we believe with an added advantage of allowing an individualized position of the polyethylene insert in response to the individual soft tissue load due to different ankle joint configurations.

Malunion of the clavicle causes significant glenoid malposition: a quantitative anatomic investigation

OBJECTIVE

An experimental cadaver model was used to assess the effects of a malunited fracture of the middle third of the clavicle on the functional anatomy of the shoulder joint.

METHOD

Anatomic samples were prepared with simulated shortening and axial malposition of the clavicle. From these, alterations in glenoid fossa position were measured and depicted graphically.

RESULTS

Healing of clavicle fractures with bony shortening leads to a ventromedialcaudal shift in glenoid fossa position. The following malpositions of the clavicle lead to the respective glenoid fossa positional changes: caudal deviation leads to a mediocaudal shift, cranial deviation leads to a dorsolateral shift of the glenoid fossa, ventral deviation causes a ventrolateral shift, dorsal deviation leads to mediocaudal shift of the fossa, cranial rotation leads to ventrolateral shift in fossa position, and caudal rotation leads to a dorsomedial shift in glenoid fossa position.

CONCLUSION

Clinical implication of these data is that bony shortening in combination with caudal displacement leads to distinct functional deficits in abduction, particularly overhead motion. Using the above data, a vector model was created to calculate position of the glenoid fossa dependent on clavicle position/malposition. The model is a valuable tool to be used for planning open reduction and fixation of clavicular fractures or malunions.

A universally applicable 68Ga-labeling technique for proteins

Although protein-based PET imaging agents are projected to become important tracer molecules in the future, the labeling of complex biomolecules with PET radionuclides is inexpedient and, most of the time, challenging.

METHODS

Here we present a straightforward labeling chemistry to attach the versatile radionuclide (68)Ga to proteins. Introducing the (68)Ga chelating agent NODA-GA-T (2,2'-(7-(1-carboxy-4-(2-mercaptoethylamino)-4-oxobutyl)-1,4,7-triazonane-1,4-diyl)diacetic acid) by reaction with proteins chemically processed with sulfo-SMCC (4-(N-maleimidomethyl)cyclohexane-1-carboxylic acid 3-sulfo-N-hydroxysuccinimide ester sodium salt) results in labeling precursors, enabling a simple and rapid kit-labeling procedure that requires no workup of the radiolabeled proteins. Various (68)Ga- proteins were labeled using this method, and the radiochemical yields and specific activities of the labeled proteins were determined. To show that the radiotracers are applicable for in vivo studies, proof-of-concept small-animal PET images were acquired in healthy rats using (68)Ga rat serum albumin for blood-pool imaging and (68)Ga-annexin V for apoptosis imaging in mice with a left ventricular myocardial infarction.

RESULTS

The proteins could be modified, yielding 1.2-1.7 (68)Ga-labeling sites per protein molecule. All investigated proteins could be labeled in high radiochemical yields of 95% or more in less than 10 min in 1 step, using acetate-buffered medium (pH 3.5-4.0) at room temperature without any further purification. The labeled proteins displayed specific activities of 20-45 GBq/μmol (540-1,200 Ci/mmol). In the proof-of-concept in vivo studies, (68)Ga rat serum albumin and (68)Ga-annexin V were successfully used for in vivo imaging. Both radiotracers showed a favorable biodistribution in the animal models, thus demonstrating the usefulness of the developed approach for the kit (68)Ga labeling of proteins.

CONCLUSION

The preprocessing of proteins proceeds in high chemical yields and with high protein recovery rates after purification. These precursors can be stored for several months at -20°C without degradation, and (68)Ga labeling can be performed in a 1-step kit-labeling reaction in high radiochemical yields. Two of the derivatized model proteins were successfully used in proof-of-concept in vivo imaging studies to prove the applicability of this kit (68)Ga-labeling technique.

Augmentation of intraarticular calcaneal fractures with injectable calcium phosphate cement: densitometry, histology, and functional outcome of 18 patients

Eighteen patients with intraarticular calcaneal fractures treated with open reduction and internal fixation and augmentation with an injectable carbonated apatite cement. Functional follow-up studies using the Zwipp Foot Score and densitometry were performed at 6-month intervals postoperatively. Histological samples of biopsies obtained at the time of hardware removal (6 months postoperatively) were also analyzed. The use of bone cement led to intermediate-term functional outcomes that were no better than those reported with conventional surgical procedures using bone graft. Patients demonstrated postoperative difficulties similar to those seen in other studies of this fracture, including pain, subtalar motion restrictions, peroneal impingement, and difficulties on uneven terrain and with toe- and heel-walking. However, compared to patients treated surgically without injectable carbonated apatite cement, full weight bearing on the affected extremity was regained at an average 4 weeks postoperatively. In addition, autogenous bone graft was not required to fill the osseous defect using this technique, minimizing morbidity and discomfort. During the present observation period of 3 years, only a slight decrease in the density of the peripheral zones of the cement block was observed. Histological examination revealed fibrous bone formation resulting from remodelling processes. Complete resorption and remodeling of the bone cement were not complete at 3 years. One patient developed a postoperative wound infection. Another displayed cement loosening secondary to failure of bony ingrowth.

Long-term high protein intake does not increase oxidative stress in rats

The maximum dietary protein intake that does not cause adverse effects in a healthy population is uncertain. We tested whether a high protein intake enhances oxidative stress. Adult rats were adapted to different casein-based diets containing either an adequate (13.8%; AP), medium (25.7%; MP), or high (51.3%; HP) level of crude protein; a fourth group received a HP diet but no RRR-alpha-tocopherol acetate (HP-toc). After 15 wk of feeding, plasma protein carbonyl concentration, liver lipid peroxide levels [thiobarbituric acid-reacting substances (TBARS)], reduced glutathione (GSH) status and leucine kinetics ([1-(13)C]leucine) were measured. Higher concentrations of protein carbonyls and TBARS were found in rats fed the AP and the HP-toc diets compared with those fed the MP and HP diets (P: < 0.05). GSH concentrations in plasma did not differ but total blood GSH concentrations were significantly (P: < 0.05) lower in rats fed the HP-toc diet compared with those fed the AP, MP and HP diets. Liver GSH concentrations were significantly (P: < 0.01) lower in rats fed the AP diet compared with the other groups. Rates of postabsorptive leucine oxidation (LeuOX) and flux (Q(Leu)) were positively correlated with the dietary protein level (for AP, MP, and HP, respectively: LeuOX, 74.9 +/- 28.5, 109 +/- 35.2, 142.3 +/- 38.4 micromol/(kg. h); Q(Leu), 425 +/- 102, 483 +/- 82, 505 +/- 80 micromol/(kg. h). Only HP-toc resulted in a significantly greater protein breakdown (PB(Leu)) and Q(Leu). No difference was seen in nonoxidative leucine disposal. Long-term intake of high protein diets did not increase variables of oxidative stress, in contrast to our initial hypothesis. An unexpected finding was that adequate protein feeding (AP) may in fact induce oxidative stress.

Multiply scattered light tomography and confocal imaging: detecting neovascularization in age-related macular degeneration

A novel technique, Multiply Scattered Light Tomography (MSLT), and confocal Infrared Imaging are used to provide diagnostic information using a comfortable, rapid, and noninvasive method. We investigated these techniques in detecting neovascularization in age-related macular degeneration. The MSLT used a Vertical Cavity Surface Emitting Laser (VCSEL) at 850 nm, while the confocal imaging technique used either the VCSEL or a 790 nm laser diode. Both were implemented into the topographical scanning system (TopSS, Laser Diagnostic Technologies, Inc.) Confocal imaging with both lasers provided different information about neovascularization as a function of focal plane, and different also from MSLT.

Automated biological target volume delineation for radiotherapy treatment planning using FDG-PET/CT

BACKGROUND

This study compared manually delineated gross tumour volume (GTV) and automatically generated biological tumour volume (BTV) based on fluoro-deoxy-glucose (FDG) positron emission tomography (PET)/CT to assess the robustness of predefined PET algorithms for radiotherapy (RT) planning in routine clinical practice.

METHODS

RT-planning data from 20 consecutive patients (lung- (40%), oesophageal- (25%), gynaecological- (25%) and colorectal (10%) cancer) who had undergone FDG-PET/CT planning between 08/2010 and 09/2011 were retrospectively analysed, five of them underwent neoadjuvant chemotherapy before radiotherapy. In addition to manual GTV contouring, automated segmentation algorithms were applied-among these 38%, 42%, 47% and 50% SUVmax as well as the PERCIST total lesion glycolysis (TLG) algorithm. Different ratios were calculated to assess the overlap of GTV and BTV including the conformity index and the ratio GTV included within the BTV.

RESULTS

Median age of the patients was 66 years and median tumour SUVmax 9.2. Median size of the GTVs defined by the radiation oncologist was 43.7 ml. Median conformity indices were between 30.0-37.8%. The highest amount of BTV within GTV was seen with the 38% SUVmax algorithm (49.0%), the lowest with 50% SUVmax (36.0%). Best agreement was obtained for oesophageal cancer patients with a conformity index of 56.4% and BTV within GTV ratio of 71.1%.

CONCLUSIONS

At present there is only low concordance between manually derived GTVs and automatically segmented FDG-PET/CT based BTVs indicating the need for further research in order to achieve higher volumetric conformity and therefore to get access to the full potential of FDG-PET/CT for optimization of radiotherapy planning.

Apparently isolated partial articular fractures of the radial head: prevalence and reliability of radiographically diagnosed displacement

The purpose of this study was to measure the prevalence and reliability of the radiographic diagnosis of displacement of apparently isolated partial articular radial head fractures and use these factors to assess treatment considerations. Among 119 radiographically visible partial fractures of the radial head not associated with other wrist, forearm, or elbow injury, 101 were classified as Mason type 1 (85%), 11 as borderline between Mason type 1 and Mason type 2 fractures (9%), and 7 as Mason type 2 fractures (6%) according to Broberg and Morrey's modification of the Mason classification. The intraobserver reliability of the classification of Mason type 1 and type 2 fractures was excellent (mean kappa, 0.85), but the interobserver reliability was only moderate (multirater kappa, 0.45). Because apparently isolated, stable partial fractures of the radial head are infrequently displaced and observers have moderate disagreement regarding the diagnosis of displacement, it is likely that displacement is overdiagnosed.

Haemophilic arthropathy of the ankle treated by total ankle replacement: a case series

The standard treatment for end-stage osteoarthritis of the ankle joint in haemophilic patients has been fusion of the ankle joint. Total ankle replacement is still controversial as a treatment option. The objective of this prospective study was to evaluate the mid-term outcome in patients treated with total ankle replacement using an unconstrained three-component ankle implant. Ten haemophilic ankles in eight patients (mean age: 43.2 years, range 26.7-57.5) treated with total ankle replacement were followed up for a minimum of 2.7 years (mean: 5.6, range 2.7-7.6). The outcome was measured with clinical and radiological evaluations. There were no intra- or peri-operative complications. The AOFAS-hindfoot-score increased from 38 (range 8-57) preoperatively to 81 (range 69-95) postoperatively. All patients were satisfied with the results. Four patients became pain free; in the whole patient cohort pain level decreased from 7.1 (range 4-9) preoperatively to 0.8 (range 0-3) postoperatively. All categories of SF-36 score showed significant improvements in quality of life. In one patient, open ankle arthrolysis was performed because of painful arthrofibrosis. For patients with haemophilic osteoarthritis of the ankle joint, total ankle replacement is a valuable alternative treatment to ankle fusion.

Substrate specificity of hybrid modules from peptide synthetases

Homologous modules from two different peptide synthetases were analyzed for functionally equivalent regions. Hybrids between the coding regions of the phenylalanine-activating module of tyrocidine synthetase and the valine-activating module of surfactin synthetase were constructed by combining the two reading frames at various highly conserved consensus sequences. The resulting DNA fragments were expressed in Escherichia coli as C-terminal fusions to the gene encoding for the maltose-binding protein. The fusion proteins were purified, and the amino acid specificities, the acceptance of different nucleotide analogues, and the substrate binding affinities were analyzed. We found evidence for a large N-terminal domain and a short C-terminal domain of about 19 kDa within the two modules, which are separated by the sequence motif GELCIGG. The two domains could be reciprocally transferred between the two modules, and the constructed hybrid proteins showed amino acid adenylating activity. Hybrid proteins fused at various consensus motifs within the two domains were inactive, indicating that the domains may fold independently and represent complex functional units. The N-terminal domain was found to be responsible for the amino acid specificity of the modules, and it is also involved in the recognition of the ribosyl and the phosphate moieties of the nucleotide substrate. For tyrocidine synthetase I, we could confine the sites for amino acid specificity to a region of 330 residues. The C-terminal domain is essential for the enzymatic activity and has a strong impact on the specific activity of the modules.

The EuroNet paediatric hodgkin network - modern imaging data management for real time central review in multicentre trials

Since 2007, children and adolescents with Hodgkin lymphomas are treated in the Europe-wide EuroNet-PHL trials. A real time central review process for stratification of the patients enhances quality control and efficient therapy management. This process includes reading of all cross-sectional-images. Since reference evaluation is time critical, a fast, easy to handle and safe data transfer is important. In addition, immediate and constant access to all the data has to be guaranteed in case of queries and for regulatory reasons. To meet the mentioned requirements the EuroNet Paediatric Hodgkin Data Network (funded by the European Union - Project Number: 2007108) was established between 2008 and 2011. A respective tailored data protection plan was formulated. The aim of this article is to describe the networks' mode of operation and the advantages for multi-centre trials that include centralized image review.

Reduced collagen degradation in polytraumas with traumatic brain injury causes enhanced osteogenesis

Patients with traumatic brain injury (TBI) and skeletal injuries have increased rates of excessive bone healing (EH = hypertrophic callus formation and/or heterotopic ossification). Polytrauma patients are often attributed higher rates of delayed fracture union. This study compares 182 total fractures in 29 isolated polytrauma patients (POLY) and 48 patients after TBI and polytrauma (TBI+POLY), examining the clinical parameters of EH versus delay. A subset of 28 patients (13 TBI+POLY, 15 POLY) underwent serological testing for the following bone turnover parameters: carboxy-terminal extension peptide of type 1 procollagen (P1CP), pyridinolene cross-linked carboxy-terminal telopeptide (1CTP), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and basic fibroblast growth factor (bFGF). There were higher rates of delayed union in the POLY patients (45% vs. 23%) and EH in the TBI+POLY patients (33% vs. 17%) (not significant = NS). More delayed unions were observed in diaphyseal fractures suffered by POLY (28%) than in TBI+POLY (15%) patients (NS). EH after pelvic fracture was apparent in 52% TBI+POLY and in 21% POLY fractures (NS). P1CP levels did not differ between the groups, but the collagen breakdown parameter 1CTP was significantly higher in the POLY group (p = 0.01-0.04). IGF-1 levels were below normal in both groups, and did not differ. IGFBP-3, an IGF-1-inhibiting and collagenase-3-activating protein, was significantly higher in POLY patients (p = 0.017-0.037). bFGF levels did not vary between groups. Increased serum levels of 1CTP and IGFBP-3 in POLY patients suggest that EH in TBI patients is secondary to decreased collagen breakdown rather than increased synthesis.

Resolution of 4-chlorobenzoate dehalogenase from Pseudomonas sp. strain CBS3 into three components

Extracts of Pseudomonas sp. strain CBS3 grown with 4-chlorobenzoate as sole carbon source contained an enzyme that converted 4-chlorobenzoate to 4-hydroxybenzoate. This enzyme was shown to consist of three components, all necessary for the reaction. Component I, which had a molecular weight of about 3,000, was highly unstable. Components II and III were stable proteins with molecular weights of about 86,000 and 92,000.

Complete talar dislocation without late osteonecrosis: clinical case and anatomic study

Avascular necrosis is a well-known, severe complication postfracture or subluxation of the talus. Type and localization of injury often permit conclusions regarding the probability of bone necrosis. In the following case, talar neovascularization was demonstrated after severe trauma, resulting in an open pilon fracture of the right tibia and complete talar dislocation with consequent destruction of the most relevant blood supply. This example shows that even after apparently irreversible injury to the arterial circulation, immediate bony reconstruction with comprehensive soft tissue management is indicated and can lead to bony healing. The anatomy of intraosseus vascularization is reviewed and discussed.

Scanning laser reflectometry of retinal and subretinal tissues

Measurements of the human ocular fundus that make use of the light returning through the pupil are called reflectometry. Early reflectometry studies were limited by poor light return from the retina and strong reflections from the anterior surface of the eye. Artifacts produced misleading results in diseases like age-related macular degeneration. Novel laser sources, scanning, confocal optics, and digital imaging provide improved sampling of the signal from the tissues of interest: photoreceptors and retinal pigment epithelial cells. A wider range of wavelengths is now compared, including the near infrared. Reflectometry now provides functional mapping, even in severe pathology.