AB1363 IMAGE PATTERN ANALYSIS IN FLUORESCENCE OPTICAL IMAGING FOR DIFFERENTIAL DIAGNOSIS IN RHEUMATIC JOINT DISEASES

Background

As outlined in previous studies, different rheumatic joint diseases present specific characteristic patterns and features in fluorescence optical imaging (FOI) (1-4).

Objectives

We tested different features in FOI for their ability to differentiate various rheumatic joint diseases such as rheumatoid arthritis (RA), osteoarthritis (OA) and psoriatic arthritis (PsA) with the aim to identify clear FOI criteria for the diseases.

Methods

FOI images from patients with RA, OA, PsA and healthy volunteers were evaluated by two readers blinded for diagnosis and calibrated against each other, using the prima vista mode (PVM) and the 5-phase model. For the latter, the overall time course of FOI in each hand was divided into 5 phases with a computational algorithm. Phases 1 and 2 describe the inflow (start to 15% and 15%-90% on rising edge), phase 3 is the peak phase and phases 4 and 5 comprise the outflow (90%-36.8% and 36.8% to end on falling edge). Twenty-six different features were defined by an atlas, for example the streaky pattern feature (T) as a signal enhancement around the PIP area that appears streaky, whereby the stripes are orthogonal to the finger axis (Figure 1a). The cloudy pattern (W) is visible during the inflow on the back of the hand (Figure 1b). The enthesis feature (E) depicts a V shaped and filled pattern between nail and DIP (Figure 1c). The feature frequency in each patient and phase (PVM, 5-phase) was counted and statistically analysed.

Figure 1.

Examples for FOI patterns and features: a) (T) Streaky pattern in PVM image (OA); b) (W) Cloudy pattern on the back of the hand in phase 1 (PsA); c) (E) Enthesis pattern in phase 3.

Results

In total, 128 patients (RA (age mean 54.2; SD 10.6; median 52.4), OA (58.0; 14.3; 60.1), and PsA (47.9; 12.7; 46.8)) and healthy volunteers (32 in each group) were included in the feature reading. In our analysis, OA can be differentiated from RA on the basis of the feature T. Feature T is found in phase 3 (χ2: 4.61; diagnostic odds ratio (DOR): 7.49; sensitivity (TPR) 0.11; specificity (TNR): 0.98; positive predictive value (PPV): 0.87; negative predictive value (NPV): 0.52), phase 5 (χ2: 18.5; DOR: 5.60; TPR 0.55; TNR: 0.82; PPV: 0.76; NPV: 0.64 and PVM (28.3; 12.1; 52%; 92% 87%; 65%). By means of the feature E, a distinction between RA and PsA is only limited possible (χ2: 9.58; DOR: 3.65; TPR 0.40; TNR: 0.84; PPV: 0.71; NPV: 0.59). But PsA can well be distinguished from RA by the appearance of pattern W in phase 1 (χ2: 7.68; DOR: 6.92; TPR 0.19; TNR: 0.97; PPV: 0.86; NPV: 0.54).

Other significant features yield high specificity (70%-98%) while having low sensitivity (12%-52%).

Conclusion

This work demonstrates that FOI feature analysis has the potential for differential diagnosis with FOI, which could optimize the (early) diagnostic process of rheumatic joint diseases. A majority of features yield high specificity, but only low sensitivity. The combination of different features using artificial intelligence might lead to improved diagnostic accuracy.

References

[1]Werner SG, et al. Inflammation assessment in patients with arthritis using a novel in vivo fluorescence optical imaging technology. Ann Rheum Dis. 2012; 71(4):504-510.

[2]Glimm AM, et al. Analysis of distribution and severity of inflammation in patients with osteoarthitis compared to rheumatoid arthritis by ICG-enhanced fluorescence optical imaging and musculoskeletal ultrasound: a pilot study. Ann Rheum Dis. 2016; 75(3):566-570.

[3]Wiemann O, et al. The “green nail” phenomenon in ICG-enhanced fluorescence optical imaging - a potential tool for the differential diagnosis of psoriatic arthritis. J Dtsch Dermatol Ges. 2019;17(2):138-147.

[4]Schmidt A, et al. Detection of subclinical skin manifestation in patients with psoriasis and psoriatic arthritis by fluorescence optical imaging. Arthritis Res Ther. 2020; 22(1):192.

Disclosure of Interests

None declared

First Report of White Pine Blister Rust in Nevada

White pine blister rust, caused by Cronartium ribicola Fisch., was found in 1997 infecting white pines (genus Pinus, subgenus Strobus) at two locations in the Carson Range of western Nevada. Rust incidence, infection age, damage to trees, rust phenology, and host distribution were evaluated at one of these locations and a nearby location in California in 1998. At the first location (39.3°N, 119.9°W), C. ribicola was found infecting 24 of 49 whitebark pines (P. albicaulis Engelm.) near Mt. Rose Summit on Highway 27 at 2,710 m elevation, ≈6 km northeast of Incline Village, Washoe County, NV. Among infected trees, 33% had only branch cankers, 54% had live stem cankers, and 12% had stem cankers that had killed portions of trees distal to cankers. No trees had died from infection. At the second location (39.1°N, 119.9°W), we found only 6 of 50 (12%) infected western white pines (P. monticola Dougl.) near Genoa Peak (≈2,750 m elevation), 3 km east of Lake Tahoe, Douglas County, NV; however, stem cankers occurred on 4 of the 6 infected trees. In September 1998, whitebark pines at Mt. Rose and Tahoe Meadows (2,550 m elevation, 1.5 km southwest of Mt. Rose Summit) were examined, and the following was observed: (i) aeciospore production was at its peak, indicating that sporulation can occur exceptionally late in the season in this region; (ii) signs of blister rust infection were absent on the telial hosts of C. ribicola (Ribes cereum, R. montigenum, and R. nevadense) at both locations; (iii) ≈80% of the cankers occurred on host wood produced in 1978 and 1979; and (iv) the oldest cankers originated on wood produced in 1968 and the youngest on wood produced in 1980. In October 1998, infected western white pines were examined at a location (2,650 m elevation) ≈30 km north of Lake Tahoe on Babbitt Peak, Sierra County, CA (39.6°N, 120.1°W). At this location, no trees had died from infection, fresh aeciospores were abundant on live cankers, R. montigenum and R. cereum were present but did not show signs of infection, and 19 of 20 cankers examined were on wood produced between 1978 and 1980. White pine blister rust was not found at any of 10 other locations examined throughout Nevada from 1995 to 1997. This is believed to be the first documented report of C. ribicola infecting white pines in Nevada and the easternmost extension of blister rust in the Sierra Nevada Region. These observations suggest that our understanding of blister rust spread and infection dynamics east of the Sierra Nevada crest is incomplete and that future surveys and research in this region must address, among other issues, timing of aeciospore production on pine, and the possibility of blister rust spread into the Great Basin.

The mechanism of delayed selfing in Collinsia verna (Scrophulariaceae)

Collinsia verna, blue-eyed Mary, has floral attributes of an outcrossing species, yet most flowers readily self-pollinate under greenhouse conditions. Here we describe the mechanism of self-pollination in C. verna via changes in relative positions of the stigma and anthers and late timing of receptivity, resulting in delayed selfing. Each flower contains four anthers that dehisce sequentially over ∼1 wk. Pollen that is not collected by pollinators accumulates in the keel petal and retains high viability (>80% pollen germination) up to the time of corolla abscission. The stigmatic surface does not become receptive until after the third anther dehisces. This overlap in the sexual phases is concurrent with a change in herkogamy during floral development. In most flowers (70%), the stigma has moved to the front of the keel and is positioned near the anthers when the third anther dehisces. Under field conditions, fruiting success of plants within pollinator exclosures was ∼75% of the fruiting success in open-pollinated plants (33% fruiting success via autogamy vs. 44% fruiting success, respectively). Collinsia verna plants in pollinator exclosures exhibit variation in autogamy rates within natural populations (range 0-80%). In addition, only half of naturally pollinated, receptive flowers examined had pollen tubes growing in their styles. In contrast, shortly after corolla abscission, nearly all flowers examined (96%) had pollen tubes in their styles. Thus we find that in C. verna, autogamy occurs late in floral development, which has the potential to provide substantial reproductive assurance, and that individuals vary in their ability to set fruit through this mechanism. We suggest that delayed selfing mechanisms may be overlooked in other species and that variable pollinator availability may play a significant role in the maintenance of mixed mating in species with delayed selfing, such as C. verna.