Medical laser application : international journal for laser treatment and research最新文献

Diagnostic imaging of the upper urinary tract is a cumbersome process that involves a multitude of different imaging modalities, including ultrasonography, conventional radiography, X-ray fluoroscopy (retrograde and antegrade ureteropyelography), endoscopy (cystoscopy and ureterorenoscopy) without or with biopsy, multi-detector-row computed tomography (MDCT), and magnetic resonance imaging (MRI). However, these modalities leave a diagnostic gap because they cannot demonstrate different layers of the wall of the upper urinary tract. Recent research shows that catheter-based, intraluminal probes for optical coherence tomography (OCT) with near-infrared light provide cross-sectional images from within the lumen of the upper urinary tract that distinguish between the urothelium, lamina propria, and muscle layer at spatial resolutions of about 10–15 μm in axial and about 20–25 μm in lateral directions respectively. The feasibility of in vivo imaging and the superiority of OCT to endoluminal ultrasonography (ELUS) have been demonstrated. However, OCT has yet to show that it is capable of characterizing pathologic lesions, e.g., urothelial cancer. The present paper summarizes the basic principles and initial results of catheter-based, time-domain intraluminal OCT in the upper urinary tract.

Lasers are valuable tools in pulmonary medicine. Endobronchial photoresection with the Nd:YAG laser is well-established in interventional bronchoscopy. Photodynamic therapy (PDT), which uses monochromatic laser light to activate photosensitizers, has several proven and experimental indications in pulmonary medicine. Lasers serve as the light source in autofluorescence bronchoscopy (AFB), which has aided pulmonologists for nearly two decades in the early diagnosis of lung cancer. They also feature in fibered confocal fluorescence microscopy (FCFM), which promises to extend endoscopic visibility in clinical medicine to the cellular level. This paper is a review of these laser applications and their clinical results.

Following the rapid pace at which laser applications and interventions evolved during the 1980s and 1990s, laser systems are now being used extensively in all fields of otorhinolaryngology. Surgical techniques have been refined and adapted to standards of minimally invasive operations. As long-term results are now widely available, especially in endolaryngeal and endopharyngeal laser surgery for malignant lesions, the indications for laser interventions versus conventional surgery are more clearly defined and have become less controversial. The original diversity of laser systems has now been concentrated into fewer systems for which the clinical experience is equally widespread. Current developments are focused on the application of laser energy and intelligent laser power control. This allows surgeons to concentrate on the actual resection task at hand. Future developments include precise non-thermal ablation techniques with femtosecond and picosecond lasers but also feedback-controlled systems which rely on diagnostic parameters that are evaluated automatically during the resection process. Another field of application is the non-destructive stimulation of inner ear hair cells or auditory neurons which has opened up new perspectives for the development of hearing aids or cochlear implants.

Laser-induced lithotripsy and photodynamic therapy (PDT) are among the most important laser applications in urology. Laser lithotripsy has revolutionized urinary calculi treatment. Today, Ho:YAG laser lithotripsy using a small-caliber ureteroscope can be considered to be the first choice for treatment of ureteral calculi. In contrast to laser-induced lithotripsy, PDT is not yet firmly established in urological clinical routine. However, preclinical and clinical trials with PDT in urology are showing promise in the treatment of malignancies at multiple sites. The present article gives a review of the literature from both fields and discusses the current status of laser lithotripsy and PDT in urology.

Objective

Diffuse neonatal hemangiomatosis (DNH) is a severe disease with multiple organ involvement. If left untreated, it results in high mortality rates. Death occurs due to intractable heart failure following arteriovenous shunting or due to massive cerebral or gastrointestinal bleeding. If there are large liver hemangiomas and medical treatment is not sufficient, it is necessary to use interventional or surgical procedures such as embolization or ligation of the hepatic artery. We present another local tumor destruction procedure to treat liver hemangiomas in DNH, the interstitial laser therapy (ILT).

Method

ILT was performed in a 3-month-old male infant suffering from DNH with intractable heart failure and multiple liver hemangiomas. Due to the severity of the infant's condition and the minimally invasive character of the treatment, the ILT was performed directly in the neonatal intensive care unit. The ILT was carried out percutaneously by guiding a bare fiber (0.6 mm core diameter) via a puncture needle into the pathologically altered liver region. A Nd:YAG laser (1064 nm) was used as a light source for ILT because its light penetrates deeply into biological tissue. Tissue destruction was achieved with moderate laser power of 4–6 W and a long application time of 90–300 s. Using these applied physical laser parameters, almost spherical volumes of coagulation necrosis could be obtained with diameters of up to 1–2 cm. Puncture and the laser application were monitored by color-coded duplex sonography (CCDS). A decrease in color signal intensity at the tip of the bare fiber indicated the increasing tissue coagulation during application time.

Results

After 2 sessions of ILT of liver manifestation in 10 days the cardiac output was reduced by 50%. Postoperative Doppler imaging showed fibrosis in the treated areas of the liver. The child was transferred back to his country of origin but he died 3 months later of intracranial bleeding.

Conclusion

In our opinion interstitial laser therapy can be an effective minimally invasive method to treat life-threatening liver hemangiomas in diffuse neonatal hemangiomatosis.