Exploration of AI-Assisted On-Board Perfusion Imaging Technique on Patients Undergoing Thoraxradiotherapy

PURPOSE/OBJECTIVE(S)

Pulmonary function of lung cancer patients can significantly change along the radiation therapy (RT) course. Scholars have synthesized lung function maps from computed tomography (CT) images. Still, there is lack of study exploring the feasibility of generating lung perfusion information from cone-beam CT (CBCT). Our study aims to fill up this gap in the body of literatures.

MATERIALS/METHODS

One-hundred-and-six pairs of planning CT and CBCT images of thoracic cancer patients from XX hospital were collected retrospectively. All CT images were registered to CBCT with a deformable algorithm, and referred as deformed planning CT (dCT). A 2D convolutional neural network (CNN) model built with cycle generative adversarial network (cycle-GAN) was trained to correct CBCT image artifacts and HU value discrepancies. The corrected CBCT was named enhanced CBCT (eCBCT) in this study. All CBCT, eCBCT and dCT images were then input to a pre-trained CT-to-perfusion deep learning (DL) model to synthesize perfusion images (PI), namely PICBCT, PIeCBCT and PIdCT respectively. For model training, 80 image pairs were assigned to the training set while others to the testing set. dCT and PIdCT were respectively regarded as the ground truth in two consecutive models. One extra validation case acquired with SPECT perfusion scan was collected for model performance test. Quantitative evaluation was done between the ground truth and the synthesized images. Peak signal-to-noise ratio (PSNR) and mean absolute error (MAE) were computed to assess efficacy of CBCT enhancement. Correlation (R) and Dice similarity coefficient (DSC) were used to evaluate voxel-wise and function-wise concurrence in CBCT-derived perfusion mapping.

RESULTS

In CBCT enhancement, [eCBCT-dCT] pairs demonstrated higher agreement than [CBCT-dCT] pairs. Quantitatively, PSNR and MAE were improved from 21.10±1.60 to 24.08±1.76, and 68.99±13.51 to 47.06±11.31 (p<0.01), respectively. For perfusion translation, higher correlation was demonstrated in both voxel-wise and function-wise evaluation within [PIeCBCT-PIdCT] than [PICBCT-PIdCT]. R correlation increased from 0.84±0.09 to 0.89±0.06 (p<0.01), whereas DSC in high-functional regions increased from 0.77±0.06 to 0.82±0.05 (p<0.01). In the validation case, strong correlation was observed between SPECT perfusion scan and PIeCBCT, with R increasing from 0.57 to 0.65 when compared to PICBCT.

CONCLUSION

We proposed a novel DL framework that synthesized perfusion images from fractionally acquired CBCT. Our framework met the clinical needs in providing real-time lung perfusion maps. It can be used to track the continuously changing pulmonary function status throughout the RT course using routinely scanned CBCT, without additional imaging modalities. The framework can facilitate functionally guided adaptive radiation therapy by providing immediate pulmonary function information.

Eight-year follow-up of a randomized clinical trial comparing ultrasound-guided foam sclerotherapy with surgical stripping of the great saphenous vein

BACKGROUND

This was an 8-year follow-up of an RCT comparing ultrasound-guided foam sclerotherapy (UGFS) with high ligation and surgical stripping (HL/S) of the great saphenous vein (GSV).

METHODS

Patients were randomized to UGFS or HL/S of the GSV. The primary outcome was the recurrence of symptomatic GSV reflux. Secondary outcomes were patterns of reflux according to recurrent varices after surgery, Clinical Etiologic Anatomic Pathophysiologic (CEAP) classification, Venous Clinical Severity Score (VCSS) and EuroQol Five Dimensions (EQ-5D™) quality-of-life scores.

RESULTS

Of 430 patients originally randomized (230 UGFS, 200 HL/S), 227 (52·8 per cent; 123 UGFS, 103 HL/S) were available for analysis after 8 years. The proportion of patients free from symptomatic GSV reflux at 8 years was lower after UGFS than HL/S (55·1 versus 72·1 per cent; P = 0·024). The rate of absence of GSV reflux, irrespective of venous symptoms, at 8 years was 33·1 and 49·7 per cent respectively (P = 0·009). More saphenofemoral junction (SFJ) failure (65·8 versus 41·7 per cent; P = 0·001) and recurrent reflux in the above-knee GSV (72·5 versus 20·4 per cent; P = 0·001) was evident in the UGFS group. The VCSS was worse than preoperative scores in both groups after 8 years; CEAP classification and EQ-5D® scores were similar in the two groups.

CONCLUSION

Surgical stripping had a technically better outcome in terms of recurrence of GSV and SFJ reflux than UGFS in the long term. Long-term follow-up suggests significant clinical progression of venous disease measured by VCSS in both groups, but less after surgery. Registration number: NCT02304146 (http://www.clinicaltrials.gov).

Clarivein® mechano-chemical ablation an interim analysis of a randomized controlled trial dose-finding study

Objectives

The ClariVein® system is an endovenous technique that uses mechano-chemical ablation to treat incompetent truncal veins. This study was conducted to identify the ideal Polidocanol dosage and form for mechano-chemical ablation in order to occlude the great saphenous vein. When adhering to safe dosage levels, sclerosants with higher concentrations potentially limit the extent of treatment. It has been demonstrated that this problem may be overcome by using Polidocanol as a microfoam. This paper was established on findings of a preliminary analysis.

Material and methods

The initial study was a single-blinded multicenter randomized controlled trial where patients are allocated to three treatment arms. Group 1 consisted of mechano-chemical ablation +2% Polidocanol liquid, group 2: mechano-chemical ablation +3% Polidocanol liquid and group 3: mechano-chemical ablation +1% Polidocanol foam

Results

Eighty-seven, 34 males and 53 females (60.9%), mean age 55 years s.d. 16.0 (range 24–84), were enrolled in the study. Treatment length was 30 cm (range 10–30) for 95.2% of the patients. Mean operating time was 16 minutes (range 5–70). The mean saphenofemoral junction diameter (7.7 mm) was similar in all three groups. At 6 weeks post-treatment duplex ultrasound showed that 25 out of 25 = 100%, 27 out of 28 = 96.4% and 13 out of 23 = 56.5% were occluded in the mechano-chemical ablation + 2% Polidocanol liquid, mechano-chemical ablation + 3% Polidocanol liquid and mechano-chemical ablation + 1% Polidocanol microfoam respectively ( p < 0.001). However, stricter scrutiny showed that the anatomical success rate defined as occlusion of at least 85% of the treated length to be 88.0%, 85.7% and 30.4% respectively ( p < 0.001).

Conclusion

Mechano-chemical ablation using ClariVein® combined with 1% Polidocanol microfoam is significantly less effective and should not be considered as a treatment option of incompetent truncal veins. Further investigation to determine the ideal Polidocanol liquid dosage with mechano-chemical ablation is advocated and is being conducted accordingly.

Conservative versus surgical treatment of venous leg ulcers: 10-year follow up of a randomized, multicenter trial

Introduction

Leg ulcers have a large socio-economic impact. Treatment modalities are either conservative or surgical. Conservative treatment involves local treatment and compression therapy. Surgical treatment of venous ulcers is based on correcting venous hypertension, by treating incompetent superficial, deep, and perforating veins. A prospective randomized multicenter trial comparing surgical treatment (combined superficial and perforating vein surgery) with ambulatory compression therapy was conducted during 1998 and 2001. This paper presents the results of a 10-year follow-up period of this trial.

Materials and methods

All patients enrolled in the original prospective trial were approached and invited for additional examination and duplex ultrasound evaluation. Secondary, disease specific and generic quality-of-life (QoL) was assessed. Current ulcer state and recurrence during the follow-up period was assessed.

Results

After a mean of 97 months follow up, 80 (41%) out of 196 legs could be inspected. The incidence of “ulcer-free”, the main outcome, was significantly ( p = 0.007) higher in the surgical group (58.9%), compared to the conservative group (39.6%). Observed ulcer recurrence was 48.9% for the surgical group and 94.3% for the conservative group. The number of incompetent perforating veins appears to be a significant ( p < 0.001) risk factor for not being ulcer-free. Disease specific QoL showed no significant difference between the surgical and conservative groups.

Conclusions

The addition of surgical treatment in patients with venous ulceration leads to a significantly higher chance of being ulcer-free, than just ambulatory compression therapy. This effect persists after 10 years of follow up. The number of incompetent perforating veins has a significant effect on the ulcer-state and recurrence.

Prognostic factors associated with clear cell sarcoma in 14 Chinese patients

PURPOSE. To identify prognostic factors associated with clear cell sarcomas in 14 Chinese patients. METHODS. Medical records of 7 men and 7 women (mean age, 36 years) with histologically confirmed clear cell sarcoma of tendons and aponeuroses were reviewed. Patient demographics, tumour characteristics, and treatment modalities were retrieved. Prognostic factors associated with favourable 5-year survival were determined. RESULTS. The most affected sites were the thigh (n=5) and the foot (n=4); the mean time from symptom onset to diagnosis was 9.5 months. The tumour stage at diagnosis was IIA in 8 patients, IIB in 2, and III in 4. The mean tumour size was 4.5 cm in diameter. One patient was lost to follow-up. For the remaining 13 patients, the mean time to disease-related mortality was 2.5 years. Nine patients had distant metastases; the most common sites were lungs and pleura (n=7), followed by distant lymph nodes (n=4), bone (n=2), pericardium (n=2), and brain (n=1). All patients underwent surgical excision. Three women and one man (mean age, 27 years) attained 5-year disease-free survival. All had stage IIA tumours at diagnosis. Their mean tumour size was 1.75 cm in diameter, which was significantly smaller than that of all patients (4.5 cm). Tumour size of ≤ 2.5 cm in diameter (p=0.004) and stage IIA tumour at diagnosis (p=0.04) were significant prognostic factors for 5-year survival. CONCLUSION. Tumour size of ≤ 2.5 cm and early stage tumour are associated with 5-year disease-free survival. Early detection is crucial for the prognosis of clear cell sarcomas.

Asymptomatic grade-2 central chondrosarcoma of the distal femur with non-aggressive radiological features

This paper discusses the case of a 57-year-old man with an incidental finding of a radiologically non-aggressive chondroid lesion and concomitant osteonecrosis in the left distal femur. The final resected specimen showed a grade-2 chondrosarcoma. This case illustrates that long-term follow-up is necessary for non-aggressive chondroid lesions. If surgical management is considered, resection with an adequate margin is superior to intralesional curettage.

A sarcoma of 23 years' duration: symptom duration is not a reliable parameter to exclude malignancy

This report describes a 31-year-old woman with a 23-year history of a right buttock mass that was otherwise asymptomatic, but was proven to be a low-grade fibromyxoid sarcoma (a fully malignant soft tissue tumour with a potential for distant metastasis). This case illustrates that a long-standing tumour does not necessarily imply a benign pathology. A vigilant approach should be taken for any tumours that are of significant size (larger than 5 cm).

A MODIFIED PERIUNGUAL APPROACH FOR TREATMENT OF SUBUNGUAL GLOMUS TUMOUR

Subungal glomus tumours are uncommon; the only treatment is complete surgical excision. Transungual approach is often preferred; however, secondary nail deformity may occur. Lateral periungual approach is used to avoid this complication, but this approach provides limited exposure and is used for peripheral lesion only. We describe a modified periungual approach which can be applied to central lesions. This approach can provide adequate exposure for complete excision of the subungual tumour while avoiding incision of the nail bed.

Brodie's abscess of the ulna caused by Salmonella typhi

Osteomyelitis caused by Salmonella typhi is rare in patients with no haemoglobinopathies or other diseases causing immunosuppression. Brodie's abscess is a special variety of subacute or chronic osteomyelitis. An otherwise healthy woman who presented with forearm swelling for 6 months was diagnosed with a Brodie's abscess of the ulna caused by Salmonella typhi. Magnetic resonance imaging and a computed tomography-guided needle biopsy were performed. She was later found to be a Salmonella carrier. The Brodie's abscess was treated by surgical debridement and a course of antibiotics. The clinical, radiological, and management aspects of the disease are discussed.

Computed tomography-guided percutaneous radiofrequency ablation of osteoid osteoma: local experience

Osteoid osteoma is a slow-growing tumour with limited growth potential. In the past, treatment comprised open surgery with en-bloc resection or curettage of the tumour. In recent years, various minimally invasive percutaneous treatments have gained popularity. We report on six patients who underwent computed tomography-guided percutaneous radiofrequency ablations of osteoid osteomas between January 2000 and December 2003 in a regional hospital in Hong Kong. Technical success was achieved in all procedures, with a mean follow-up of 40 months (range, 18-65 months). Five of the six patients achieved complete pain relief after the procedure and remained pain-free on subsequent follow-up. One patient with persistent symptoms after the first ablation was successfully treated with a second ablation. The mean in-hospital stay was 2.4 days. Progress in radiological healing was observed in all patients. There was one complication of skin burn over the needle entry site. Our experience shows that percutaneous computed tomography-guided radiofrequency ablation is a minimally invasive and cost-effective treatment for osteoid osteoma.

Management of extremity soft tissue sarcoma after unplanned incomplete resection: experience of a regional musculoskeletal tumour centre

This study reviews the presentation and management of extremity soft tissue sarcoma after unplanned incomplete resection in a musculoskeletal tumour centre in Hong Kong. Medical records of 18 patients who were referred to our centre for further management from January 1995 to May 2001 after inadequate tumour excision were reviewed. Fourteen patients had been referred from private clinics and four from public hospitals. At initial presentation, 10 patients had lesions exceeding 5 cm, nine had a tumour deep in the subfascial plane, and eight had tumours that had recently increased in size. Sixteen had no preoperative radiological assessment or biopsy performed before excision. All except two patients needed additional skin and muscle reconstruction in a subsequent re-resection, and 12 required postoperative radiotherapy. Two patients subsequently developed distant metastases, and one patient died of an unrelated cause. No amputations were required, and no major complications arose from second surgery. Physicians' alertness towards the possible malignancy of soft tissue masses in extremities is important to avoid a potentially mutilating second resection. Well-planned re-resection in a specialised tumour centre can achieve satisfactory local control of disease.

Influence of the thermal effect on the TEM00 mode output power of a laser-diode side-pumped solid-state laser

A fraction of pump power has been converted to TEM00 mode laser power for a side-pumped solid-state laser by use of a space-dependent rate equation. We investigated the pump-to-mode (TEM00) ratio when scaling laser-diode side-pumped solid-state lasers to high-power levels by including the thermal effect in the space-dependent rate equation. Based on the assumption that Gaussian pump power is the same at any cross section of a laser rod, we resolved the output power with a space-dependent rate equation; temperature distribution in the laser rod was obtained; the optical path difference distribution was derived, and we estimated the diffraction losses that result from thermally induced spherical aberration by use of the Strehl intensity ratio. We determined that thermally induced diffraction losses are strongly dependent on pump power and on the pump-to-mode ratio.

Green up-conversion emission in Er3+:BaTiO3 sol-gel powders

Bright green emissions at 549 and 526 nm have been observed from sol-gel derived Er3+:BaTiO3 powders upon excitations at two near infrared (NIR) wavelengths of 973 and 816 nm. The decay characteristics were measured and studied. It was found that the predominant emission at 549 nm has very different lifetimes upon excitation at 973 and 816 nm, which was explained by the mechanisms of excited state absorption (ESA) of individual Er3+ ion and cooperative energy transfer (CET) between two near Er3+ ions for the up-conversion emission. Analysis also showed that 973-nm excitation is more effective for the green up-conversion emission.

Embossed Bragg Gratings Based on Organically Modified Silane Waveguides in InP

Considering the large variety of applications for optical glass waveguide gratings, the effective production method of embossing for micropatterning, and the unique advantages of InP-based materials, we expect that hybridization of embossed optical glass waveguide gratings and InP substrates will inevitably lead to new applications in integrated optics. We present our preliminary results of research toward the development of solgel-derived glass waveguide gratings made by embossing on InP. Theoretically, the dependence of the stop-band FWHM and transmission contrast of the grating filter on the grating length, and the relationship between the Bragg grating's reflective wavelength and the dopant concentration in the solgel waveguide, are obtained. Experimentally, using organically modified silane, we solve the problem of mismatching of SiO(2) and InP, and successfully fabricate an embossed glass grating with a second-order Bragg reflection wavelength of 1580 nm and a FWHM of 0.7 nm fabricated upon a solgel waveguide on an InP substrate.

Efficient method for evaluation of the diffraction efficiency upper bound of diffractive phase elements

The theoretical diffraction efficiency upper limit of diffractive phase elements (DPE's) with finite apertures is investigated. A successful numerical method of evaluating the efficiency upper bound of DPE's is proposed. The method includes a hybrid optimization procedure that combines a genetic algorithm with the conjugate gradient method. This efficient global optimization technique can also be used to design DPE's. Simulation computations are detailed for rotationally symmetric beam shaping in which a Gaussian profile laser beam is converted into a uniform beam. Numerical results demonstrate that the estimated diffraction efficiency upper bound is consistent with the design results.

Fluorescence feedback control of an active Q-switched diode-pumped Nd:YVO4 laser

We have implemented active feedback control in a Q-switched diode-pumped Nd:YVO(4) laser by monitoring the fluorescence intensity from the laser crystal. When the initial inversion level indicated by the detected fluorescence has reached a predetermined value, Q switching is initiated. This scheme allowed us to vary the reproducibility of the output pulse peak power and pulse width. The novel active Q-switching approach can reduce the shot-to-shot variations of the output pulse peak power and the pulse width.

The anatomic basis and clinical applications of flaps based on the posterior tibial vessels

The vascular anatomy of the posterior tibial vessels has been studied in 20 legs of 10 cadavers. The number, size and distribution of the direct cutaneous and direct muscle branches of the posterior tibial vessels were recorded. For analysis, the leg was divided into four equal segments, Zone I being the most distal and Zone IV the most proximal. The direct cutaneous branches were found to cluster mainly around Zone II. The direct muscle branches to the soleus and flexor digitorum longus muscles arose chiefly in Zones II and III. Based on this knowledge, we performed fasciocutaneous, island soleus muscle, musculo-fasciocutaneous and flexor digitorum longus muscle flaps based on the posterior tibial vessels in 12 patients. Four were free fasciocutaneous flaps and eight were pedicled flaps. All flaps survived and there were no major complications. Delayed wound healing was encountered in three patients.