Burn imaging with a whole field laser Doppler perfusion imager based on a CMOS imaging array

Laser Doppler perfusion imaging (LDPI) has been proven to be a useful tool in predicting the burn wound outcome in an early stage. A major disadvantage of scanning beam LDPI devices is their slow scanning speed, leading to patient discomfort and imaging artifacts. We have developed the Twente Optical Perfusion Camera (TOPCam), a whole field laser Doppler perfusion imager based on a CMOS imaging array, which is two orders of magnitude faster than scanning beam LDPI systems. In this paper the first clinical results of the TOPCam in the setting of a burn centre are presented. The paper shows perfusion images of burns of various degrees. While our system encounters problems caused by blisters, tissue necrosis, surface reflection and curvature in a manner similar to scanning beam imagers, it poses a clear advantage in terms of procedure time. Image quality in terms of dynamic range and resolution appears to be sufficient for burn diagnosis. Hence, we made important steps in overcoming the limitations of LDPI in burn diagnosis imposed by the measurement speed.     

Prospective comparative evaluation study of Laser Doppler Imaging and thermal imaging in the assessment of burn depth

Introduction

The accurate assessment of burn depth is challenging but crucial for surgical excision and tissue preservation. Laser Doppler Imaging (LDI) has gained increasing acceptance as a tool to aid depth assessment but its adoption is hampered by high costs, long scan times and limited portability. Thermal imaging is touted as a suitable alternative however few comparison studies have been done.

Burn wound healing time assessed by laser Doppler imaging. Part 2: validation of a dedicated colour code for image interpretation

Introduction

Laser Doppler imaging (LDI) has been investigated and used since 1993 for the assessment of burn wounds. Here we describe tests that validate use of the dedicated colour palette, derived in Part 1, for a standardised interpretation of LDI images for prediction of healing time (<14 days, 14-21 days or >21 days). We also describe clinical and technical factors to be taken into account during LDI imaging and during image interpretation.

Methods

(1) A cohort of images, selected at random, were assessed, according to strict rules of interpretation, by 6 clinicians against photographs of healing, for accuracy of healing time prediction and clinical usefulness using five-point scales. (2) All images were assessed technically in a similar way for accuracy and the accuracy was further studied by analysing the data by ordinal logistic regression to predict the dependence of burn healing time on demographic variables (age, sex, race, %TBSA, burn cause and site). (3) Where average LDI blood flow could be determined, regression analysis was used to assess the potential accuracy of the technique.

Results

(1) Clinical accuracy was found to be 93% and usefulness was 89%; (2) technical accuracy was found to be 96%; (3) regression analysis found that a potential accuracy of 90.9% could be achieved using LDI results alone, increasing to 92% if gender was also considered; no other parameters had an influence on healing time prediction.

Conclusion

LDI can be used in a standardised way as a valid tool for improving on clinical assessment of burn wounds. This can enable earlier appropriate management.     

Accuracy of early burn depth assessment by laser Doppler imaging on different days post burn

Background

Accurate diagnosis of burn depth is essential in selecting the most appropriate treatment. Early assessment of burn depth by clinical means only has been shown to be inaccurate, resulting in unnecessary operations or delay of grafting procedures. Laser Doppler imaging (LDI) was reported as an objective technique to determine the depth of a burn wound, but the accuracy on very early days post burn has never been investigated yet.

Methods

In 40 patients with intermediate depth burns, we prospectively evaluated and compared the accuracy of the LDI measurements with the clinical assessments on days 0, 1, 3, 5, 8. Clinical evaluation of the depth of the burn was performed by two observers blinded to the LDI images. Accuracies were assessed by comparison with outcome: healing times longer than 21 days were considered to be equivalent to a biopsy finding of a deep dermal wound. Obviously superficial and full thickness wounds were excluded. LDI flux level was used for LDI prediction of outcome: less than 220 PU to predict non-healing at day 21.

Results

The accuracies of burn depth assessments on the day of burn and post burn days 0, 1, 3, 5 and 8 using LDI were 54%, 79.5%, 95%, 97% and 100% compared with clinical assessment accuracies of 40.6%, 61.5%, 52.5%, 71.4% and 100%, respectively. LDI accuracy was significantly higher than clinical accuracy on day 3 (p < 0.001) and day 5 (p = 0.005). Burn depth conversion was also considered. This is the first study to quantify the advantage of LDI scanning over clinical assessments during these important early after burn days.     

Initial evaluation of prostate cancer with real-time elastography based on step-section pathologic analysis after radical prostatectomy: A preliminary study

OBJECTIVE: To determine whether real-time elastography can be used to detect prostate cancer as a relatively non-invasive modality based on the tissue strain value. PATIENTS AND METHODS: Seventeen patients underwent real-time elastography in conjunction with digital rectal examination (DRE), conventional gray-scale transrectal ultrasonography (TRUS), color Doppler ultrasonography (CDUS), and magnetic resonance imaging (MRI) prior to radical prostatectomy. The elastogram was compared to findings of conventional modalities and pathological findings of prostatectomy specimens. To obtain the elastogram, compression of the prostate was performed along with a visual indicator on a video screen. RESULTS: Twenty of 27 pathologically confirmed tumors were detected with real-time elastography. The cancer detection rate with real-time elastography was superior to the rates of other modalities and nearly equal to both on the anterior side (75.0%) and the posterior side (73.7%) of the prostate. A higher tumor detection rate for real-time elastography was observed for tumors with a higher Gleason score and larger tumor volume. CONCLUSION: In our preliminary study, real-time elastography in conjunction with gray-scale TRUS is a non-invasive modality to detect prostate cancer.     

Modeling of bioheat equation for skin and a preliminary study on a noninvasive diagnostic method for skin burn wounds

Heat transfer in a unit three-dimensional skin tissue with an embedded vascular system of actual histology structure is computed in the present work. The tissue temperature and the blood temperatures in artery and vein vessels are solved with a multi-grid system. The mean temperature of the tissue over the cross-section of the unit skin area is evaluated. The resulting one-dimensional function is regarded as the temperature of healthy tissue (or injured skin but the blood perfusion is still normally working) for large area of skin in view of the symmetric and periodic structure of the paired artery–vein vessels in nature. A three-dimensional bioheat equation then is formulated by the superposition of the skin burn wound effect and the healthy skin temperature with and without thermal radiation exposure. When this bioheat equation is employed to simulate ADT process on burn wounds, the decaying factor of the skin surface temperature is found to be a sharply decreasing function of time in the self-cooling stage after a thermal radiation heating. Nevertheless, the boundary of non-healing (needing surgery) and healing regions in a large burn wound can be estimated by tracking the peak of the gradient of decaying factor within 30 s after the thermal radiation is turned off. Experimental studies on the full ADT procedure are needed to justify the assumptions in the present computation.     

X-ray-free protocol for pectus deformities based on magnetic resonance imaging and a low-cost portable three-dimensional scanning device: a preliminary study

 Open in a separate windowOBJECTIVESTo compare a standard protocol using chest computed tomography (CT) to a non-irradiant protocol involving a low-cost portable 3D scanner and magnetic resonance imaging (MRI) for all pectus deformities based on the Haller index (HI).METHODSFrom April 2019 to March 2020, all children treated for pectus excavatum or carinatum at our institution were evaluated by chest CT, 3D scanning (iPad with Structure Sensor and Captevia—Rodin4D) and MRI. The main objectives were to compare the HI determined by CT or MRI to a derived index evaluated with 3D scanning, the external Haller index (EHI). The secondary objectives were to assess the inter-rater variability and the concordance between CT and MRI for the HI and the correction index.RESULTSEleven patients were evaluated. We identified a strong correlation between the HI with MRI and the EHI (Pearson correlation coefficient = 0.900; P < 0.001), with a strong concordance between a radiologist and a non-radiologist using intra-class correlation for the HI with MRI (intra-class correlation coefficient = 0.995; [0.983; 0.999]) and the EHI (intra-class correlation coefficient = 0.978; [0.823; 0.995]). We also identified a marked correlation between the HI with CT and the EHI (Pearson coefficient = 0.855; P = 0.002), with a strong inter-rater concordance (intra-class correlation coefficient = 0.975; [0.901; 0.993]), a reliable concordance between CT and MRI for the HI and the correction index (Pearson coefficient = 0.886; P = 0.033).CONCLUSIONSNon-irradiant pectus deformity assessment is possible in clinical practice, replacing CT with MRI and 3D scanning as a possible readily-accessible monitoring tool.