冷循环液温度对微波消融离体猪肝消融灶形态的影响

目的 观察冷循环液温度对微波消融（MWA）离体猪肝消融灶形态的影响。方法 将20块新鲜离体猪肝组织随机分为冰水冷循环组（A组）及常温冷循环组（B组）,分别以不同消融功率（50、60、70 W）及消融时间（1、5 min）于各亚组,即A1与B1（50 W,1 min）、A2与B2（50 W,5 min）、A3与B3（60 W,1 min）、A4与B4（60 W,5 min）、A5与B5（70 W,1 min）及A6与B6（70 W,5 min）亚组内各消融10个靶区。对比A、B组相同条件亚组间及组内消融灶形态,包括消融灶纵向直径（LD）、横向直径（TD）、球形指数（RI）及体积（V）。结果 相同消融功率及时间下,A组各亚组消融灶LD均小于B组（P均＜0.05）;A1 与B1、A2与B2、A4与B4、A5与B5、A6与B6亚组之间,前者消融灶RI均大于后者（P均＜0.05）,而A3与B3亚组间消融灶RI差异无统计学意义（P＞0.05）。冷循环液温度对2组消融灶TD（F=1.125）和V（F=3.332）的主效应均不显著（P均≥0.05）。相同冷循环液温度条件下,A1与A2、A3与A4、A5与A6各亚组间消融灶形态各参数差异均有统计学意义（P均＜0.05）,B组各亚组间亦然。结论 以恒定消融功率及时间行MWA消融离体猪肝时,采用冰水冷循环可使消融灶形态更接近于球形;且随消融时间延长,消融灶范围越大,则RI越高。     

三维重建辅助腹腔镜超声引导激光消融在肝脏恶性肿瘤的临床应用

背景与目的 激光消融（LA）提高了肝肿瘤消融的精度，从而降低了并发症的可能性，已成为肝脏恶性肿瘤重要的临床治疗方法之一。然而，目前关于应用三维（3D）重建辅助腹腔镜超声技术引导LA治疗肝脏恶性肿瘤的相关报道较少。因此，本研究探讨3D重建辅助腹腔镜超声引导下LA治疗肝脏恶性肿瘤的临床效果与应用价值。方法 回顾性收集2020年9月—2022年3月行3D重建辅助腹腔镜超声引导下LA治疗肝脏恶性肿瘤患者的临床资料，分析手术完成情况、手术时间、术中出血量、术后并发症发生情况、手术前后肝功能指标与肿瘤标志物变化，术后随访期间肿瘤总缓解率（ORR）和复发率。结果 共纳入35例符合纳入标准的患者，其中原发性肝癌25例、结直肠癌肝转移6例、胰腺癌肝转移2例、肺癌肝转移2例。所有患者均顺利完成手术，手术时间为（66.3±2.8）min，术中出血量为（15.9±12.4）mL。3例患者术后出现轻微并发症，包括1例胸腔积液和2例术后发热，未发生围术期严重并发症或死亡。患者术后出现转氨酶与总胆红素升高的情况，经常规保肝治疗后，术后1个月均恢复至术前水平。25例原发性肝癌患者术后3个月AFP较术前明显降低（8.2 ng/mL vs. 5.3 ng/mL，Z=-3.269，P=0.001）。所有患者在术后3个月复查增强CT，显示肿瘤ORR为100%。术后6个月再次复查增强CT，治疗的53个癌灶中2个出现局部复发，局部复发率为3.8%（2/53），再次接受LA。结论 有选择性利用3D重建辅助腹腔镜超声引导的LA治疗肝脏恶性肿瘤，具有治疗精准，侵袭性小，疗效满意的优点。尤其，对于肝脏难以定位的较小病灶、靠近重要结构的以及其他复杂情况，选择该治疗方法有利于患者。     

对比冷冻消融与微波消融治疗兔VX2椎旁肿瘤的有效性及安全性

目的 对比冷冻消融（CA）与微波消融（MWA）治疗兔VX2椎旁肿瘤的有效性及安全性。方法 选取48只新西兰大白兔建立VX2椎旁肿瘤模型并随机分为CA组（n=24）及MWA组（n=24）,比较组间完全消融率、生存率、布里斯托尔兔疼痛量表（BRPS）评分及并发症发生率。结果 CA组完全消融率及治疗后21天生存率分别为91.67%（22/24）及33.33%（8/24）,均高于MWA组［66.67%（16/24）及16.67%（4/24）］（P均＜0.05）。CA组治疗后4 h、1天、4天、7天及14天BRPS评分均低于MWA组（P均＜0.001）;2组上述时间点BRPS评分均低于治疗前（P均＜0.05）。CA组并发症发生率（3/24,12.50%）低于MWA组（8/24,33.33%）（P＜0.05）。结论 CA治疗兔VX2椎旁肿瘤的安全性及有效性均优于MWA。     

经皮微波消融治疗低风险甲状腺微小乳头状癌效果及对生活质量的影响

目的 观察经皮微波消融治疗低风险甲状腺微小乳头状癌（PTMC）的效果和对患者生活质量的影响。方法 对75例经病理证实的单发低风险（T1N0M0）PTMC患者行超声引导下经皮微波消融治疗。术后随访,分别于1、3、6、12、24个月观察治疗效果及并发症,并行躯体健康总评（PCS）、心理健康总评（MCS）和36项健康调查简表（SF-36）评分。结果 75例均顺利完成手术。消融过程中4例出现短暂声嘶,2 h内恢复;15例自觉放射性耳根痛、颈部疼痛等,消融后立即缓解。术后24个月时治疗有效率100%（75/75）,病灶消失率93.33%（70/75）,无局部复发病例。术后1、3个月病灶最大径和体积均较术前增加,术后6、12、24个月病灶均较术前缩小（P均<0.05）。术前及术后各时间点促甲状腺激素（TSH）、游离三碘甲状腺原氨酸（FT3）、游离甲状腺素（FT4）水平差异均无统计学意义（P均>0.05）。术前及术后不同时间点PCS得分差异无统计学意义（P>0.05）,术后各时间点MCS得分及SF-36总分均高于术前（P均<0.05）。结论 经皮消融治疗低风险PTMC安全、有效,并可提升患者生活质量。     

氩氦刀冷冻消融与微波消融治疗原发性肝细胞癌近期疗效及对免疫功能的影响

目的 对比CT引导下氩氦刀冷冻消融与微波消融治疗原发性肝细胞癌（pHCC）近期疗效及对患者免疫功能的影响。方法 回顾性分析52例原发性pHCC患者,其中24例接受CT引导下氩氦刀冷冻消融（冷冻组）、28例接受CT引导下微波消融（微波组）,比较2组消融后1个月疗效,分析组间及组内消融前1日与消融后4周外周血CD4⁺、CD8⁺ T淋巴细胞占比及CD4⁺/CD8⁺的差异。结果 消融后1个月,冷冻组客观缓解率（87.50%）与微波组（85.71%）差异无统计学意义（P=0.833）。消融前1日,组间外周血CD4⁺、CD8⁺ T淋巴细胞占比及CD4⁺/CD8⁺差异均无统计学意义（P均>0.05）;消融后4周,组间外周血CD4⁺、CD8⁺ T淋巴细胞占比及CD4⁺/CD8⁺差异均有统计学意义（P均<0.05）,外周血CD4⁺ T淋巴细胞占比及CD4⁺/CD8⁺均较消融前1日升高（P均<0.001）、CD8⁺ T淋巴细胞占比较消融前1日降低（P均<0.001）。结论 氩氦刀冷冻消融与微波消融治疗pHCC近期疗效确切且相当,前者增强免疫功能的效果更佳。     

超声引导经皮微波消融治疗结直肠癌肝转移瘤不良事件及其影响因素

目的 探讨超声引导经皮微波消融（MWA）治疗结直肠癌肝转移瘤（CRLM）不良事件（AE）及其影响因素。方法 回顾性分析427例接受超声引导经皮MWA治疗的CRLM患者,共治疗614例次、1 334个病灶,统计术后AE发生率及其影响因素。结果 AE总发生率4.89%（30/614）,无消融相关死亡。影响AE的危险因素包括穿刺针数（OR=1.301,P=0.005）、高危部位病灶（OR=2.829,P=0.025）、病灶数>5（OR=4.655,P=0.010）、腹腔手术史（OR=7.716,P=0.047）及肝吸虫病（OR=17.683,P=0.005）。结论 超声引导经皮MWA治疗CRLM的AE发生率较低,AE发生与病灶数目、高危部位、穿刺针数、腹腔手术史及肝吸虫病有关。     

超声引导下颈中间丛阻滞联合甲状腺囊下阻滞用于微波消融甲状腺结节

目的 观察超声引导下颈中间丛阻滞（ICPB）联合甲状腺囊下阻滞用于微波消融甲状腺结节的价值。方法 前瞻性纳入68例单发结节性甲状腺肿患者,随机将其分为干预组（n=34）和对照组（n=34）。对干预组于超声引导下ICPB联合甲状腺囊下阻滞消融,对照组于常规局部浸润麻醉后行甲状腺结节微波消融,对比组间一般资料、术中及术后情况,消融过程及消融后2、4、8及24 h分别记为T1、T2、T3、T4及T5。评价ICPB联合甲状腺囊下阻滞用于微波消融甲状腺结节的价值。结果 最终60例入组,干预组、对照组各30例;干预组患者T1~T3期间心率-血压乘积（RPP）及T1~T4期间视觉模拟量表（VAS）评分均显著低于对照组（P均<0.05）,而T2及T3期间40项恢复质量（QoR-40）评分显著高于对照组（P均<0.05）。干预组术中接受利多卡因者占比及剂量、术后口服对乙酰氨基酚占比及剂量均显著低于对照组（P均<0.05）。干预组术后未见明显并发症,对照组术后4例声嘶、2例呕吐。结论 超声引导下ICPB联合甲状腺囊下阻滞用于甲状腺结节微波消融安全性较高,可提供有效围手术期镇痛。     

基于超声列线图预测甲状腺良性结节微波消融后残留

目的 观察基于超声的多因素logistic回归模型列线图预测甲状腺良性结节微波消融（MWA）后残留的价值。方法 回顾性纳入101例接受超声引导下MWA的甲状腺良性结节患者（共133个结节）,根据MWA后1个月超声造影（CEUS）所见分为残留组（n=21）与无残留组（n=112）。比较组间MWA前甲状腺良性结节超声表现,将差异有统计学意义者纳入多因素logistic回归分析,筛选MWA后残留的独立预测因素,并绘制可视化列线图。以受试者工作特征曲线及其曲线下面积（AUC）评估列线图预测MWA后残留的区分度,以Hosmer-Lemeshow拟合优度检验评估其校准度。结果 超声显示消融存在风险及结节体积均为甲状腺良性结节MWA后残留的独立预测因素（P均＜0.05）,提示消融风险高［OR=17.637（2.528,123.019）］及体积大的甲状腺良性结节［OR=1.297（1.155,1.457）］MWA后残留风险更高。所获列线图预测甲状腺良性结节MWA后残留的AUC为0.756,Hosmer-Lemeshow检验显示拟合度较好（P=0.401）。结论 超声显示消融风险高及体积较大甲状腺良性结节MWA后残留风险较高;基于所获列线图可简便、有效地预测上述风险。     

超声引导经皮热消融与甲状旁腺切除术治疗继发性甲状旁腺功能亢进疗效与安全性比较的Meta分析

背景与目的 继发性甲状旁腺功能亢进（SHPT）是慢性肾病（CKD）常见的一种并发症,体内钙磷平衡紊乱导致甲状旁腺激素（PTH）代偿性过度分泌。药物治疗效果不佳的患者进展成为难治性SHPT,外科切除增生的甲状旁腺是目前治疗SHPT的有效方法,但手术治疗存在一定的局限性,如手术、麻醉双重风险较高,术后可发生感染、永久性甲状旁腺功能减退、瘢痕增生等潜在风险。随着科学技术的进步,热消融治疗SHPT成为研究热点,但尚缺乏统一诊疗规范,需要更多的循证医学证据促进诊疗标准化的制定。因此,本文通过比较超声引导下热消融与传统甲状旁腺切除术（PTX）治疗SHPT的临床有效性和安全性,探讨热消融术在难治性SHPT治疗中的临床应用前景。方法 检索多个国内外数据库,收集比较超声介导的热消融与传统开放式PTX治疗CKD继发的难治性SHPT的临床对照研究,检索时间为建库至2022年11月30日。根据纳入与排除标准筛选文献后。使用ReveMan 5.3软件行Meta分析。评价指标为术后3、6个月的血清PTH与血清钙水平、住院时间、低钙血症与声音嘶哑的发生率。结果 最终纳入12项研究,共1 060例患者,其中热消融组510例,PTX组550例。与PTX比较,热消融组术后3、6个月PTH水平（MD=18.18,95% CI=-21.19~57.55,P=0.37;MD=-5.35,95% CI=-32.59~21.90,P=0.70）、血钙水平（MD=-0.09,95% CI=-0.28~0.10,P=0.35;MD=-0.10,95% CI=-0.29~0.10,P=0.34）差异均无统计学意义。热消融组低钙血症发生率低于PTX组（18.5% vs. 27.3%）,差异有统计学意义（OR=0.57,95% CI=0.38~0.84,P=0.005）,两组声音嘶哑发生率差异无统计学意义（OR=0.89,95% CI=0.55~1.45,P=0.64）。热消融组住院时间明显短于PTX组（MD=-3.97,95% CI=-5.68~-2.27,P<0.000 1）。结论 超声引导经皮热消融治疗SHPT可能是PTX的一种替代技术,具备安全、有效、可重复性高、并发症少等特点,但其最终的优越性需要大样本、多中心前瞻性随机对照试验来证明。     

对比乙型与丙型肝炎背景下肝细胞癌患者经微波消融治疗后预后

目的 对比观察微波消融（MWA）治疗乙型（HB）与丙型肝炎（HC）背景下肝细胞癌（HCC）的预后。方法 回顾性分析HCC伴HB（HB-HCC）及HCC伴HC（HC-HCC）各159例患者资料,比较组间肿瘤学结局,分析患者死因,观察HCC患者MWA后总生存期（OS）的危险因素。结果 HC-HCC组OS率低于HB-HCC组（P=0.045）,组间无病生存率（P=0.095）及癌症特异性生存率（P=0.189）差异均无统计学意义。相比HB-HCC组,HC-HCC组患者死于肝硬化并发症的风险更高（HR=2.339,P=0.043）。Child-Pugh B级（HR=3.082,P＜0.001）、肝炎病毒载量＞500 IU/ml（HR=1.654,P=0.006）及病灶最大径≥3.0 cm（HR=1.541,P=0.017）均为HCC患者MWA后OS的独立危险因素。结论 相比HB-HCC患者,HC-HCC患者MWA后OS较短。     

Interstitial Nd:YAG laser ablation in normal rabbit liver: trial to maximize the size of laser-induced lesions.

In order to apply interstitial laser ablation to relatively small liver tumors in humans, it will be necessary to optimize the irradiation schedule. Nd:YAG laser was applied to normal rabbit liver in vivo at various power and energy outputs, including a protocol in which irradiation was repeated twice, with and without fiber tip advancement during the intermission. Ex vivo and in vivo tissue were also irradiated to determine the effect of perfusion on the lesion size. We obtained the same monotonic relationship between laser settings and lesion size in rabbit liver as we previously reported in rat liver. MR-guided fiber advancement between heating periods increased the transverse diameter of the lesion, and MR monitoring demonstrated this process. Our results suggest that repeated irradiation with brief intermissions, when combined with fiber advancement, may increase the lesion size.     

Alternative lasers for endoscopic surgery: comparison of pulsed thulium-holmium-chromium:YAG with continuous-wave neodymium:YAG laser for ablation of colonic mucosa.

Precise and controllable tissue vaporization is essential for minimizing risk in removal of sessile polyps from the lumen of thin walled gastrointestinal organs such as the colon. We compared the ablative efficiency on canine colonic mucosa of the THC:YAG laser with the clinically employed cw Nd:YAG laser. Fresh canine colon was treated with a progressive dose schedule using each laser at several energy/power densities. Ablation depth was measured on fresh tissue and thermal (non-ablation or coagulative) damage examined histologically. The THC:YAG ablation rates were 13.7 +/- 0.8 and 10.2 +/- 0.4 microns/J at 55 and 85 J/cm2, respectively. The Nd:YAG laser generated 3.7 +/- 0.3, 2.8 +/- 0.1, and 3.6 +/- 0.2 microns/J at 4,460, 5,095, and 5,730 W/cm2, respectively. There was a significant (P less than 0.001) difference among the THC:YAG ablation rates and between the THC:YAG and Nd:YAG ablation rates (ANOVA). The THC:YAG laser craters had significantly less collateral thermal damage than Nd:YAG. The pulsed THC:YAG laser should have an important clinical role since its use could reduce the risk of perforation in endoscopic laser procedures such as the removal of sessile polyps.     

Infrared laser bone ablation

The bone ablation characteristics of five infrared lasers, including three pulsed lasers (Nd:YAG, lambda = 1,064 micron; Hol:YSGG, lambda = 2.10 micron; and Erb:YAG, lambda = 2.94 micron) and two continuous-wave lasers (Nd:YAG, lambda = 1.064 micron; and CO2, lambda = 10.6 micron), were studied. All laser ablations were performed in vitro, using moist, freshly dissected calvarium of guinea pig skulls. Quantitative etch rates of the three pulsed lasers were calculated. Light microscopy of histologic sections of ablated bone revealed a zone of tissue damage of 10 to 15 micron adjacent to the lesion edge in the case of the pulsed Nd:YAG and the Erb:YAG lasers, from 20 to 90 micron zone of tissue damage for bone ablated by the Hol:YSGG laser, and 60 to 135 micron zone of tissue damage in the case of the two continuous-wave lasers. Possible mechanisms of bone ablation and tissue damage are discussed.     

Endometrial laser ablation in rabbits: a comparative study of three laser types

Endometrial laser ablation is one of the alternatives to hysterectomy in cases of intractable uterine bleeding. It is currently performed using the Nd:YAG laser at 1.06 microns. The aim of this study was to compare the tissue effect of three types of laser irradiation (Nd:YAG laser at 1.06 and 1.32 microns and holmium laser at 2.12 microns) on the rabbit endometrium. Crater formation, coagulation necrosis, and muscle necrosis were evaluated at the time of ablation, as well as at 1 week and 4 weeks postablation. The results were assessed by determining the depth and width of the affected portion in the uterine wall (lumen to serosa). It was shown that Nd:YAG laser at 1.32 microns caused more generalized and extended effects as compared with the other laser types examined. Endometrial regeneration was faster after ablation by the Nd:YAG laser at 1.06 microns and the holmium laser than by the Nd:YAG laser at 1.32 microns. The widest range of "ablation energy" (defined as that causing ablation without muscle damage) was achieved by applying the holmium laser. Further evaluation of the holmium laser for this indication is recommended.     

Effects of Nd:Yag laser irradiation on osteoblast cell cultures

The application of Nd:YAG lasers in endodontics has been explored by many investigators for different purposes. The aim of this in vitro study is to evaluate the effects of Nd:YAG laser on osteoblast cell cultures. A 1,064 nm Nd:YAG laser was used to irradiate human osteoblast-like cells (Saos-2) in noncontact mode for 10 s with different energy settings. The settings varied were pulse energy (20–120 mJ), pulse repetition rate (10–30 Hz), and power output (0.2–3.6 W). He–Ne, the aiming beam of Nd:YAG laser, was used in noncontact mode for 10 s. After 7-, 14-, and 21-day incubation period, cell viability and proliferation were evaluated with methylthiazoletetrazolium (MTT) colorometric method. The comparison of average MTT values gave no statistically significant difference between 20 mJ, 10 Hz, He–Ne, and control (p<0.05). The differences between all other groups were significant (p<0.05). Increase in the pulse energy, pulse repetition rate, and power output has a negative effect on the cell viability and proliferation.     

Experimental study of partial liver resection with a combined CO2 and Nd:YAG laser

The use of the CO₂ laser in liver surgery is mainly limited by the lack of coagulation of the larger vessels. In an experimental study, partial liver resections were performed on pigs with a Nd:YAG as well as with a combined CO₂ and Nd: YAG laser. The best cutting efficiency was obtained with the CO₂ laser. On the other hand, the Nd:YAG laser and the combined laser sources showed excellent hemostasis at the cutting edge corresponding with a width of necrosis at about 5 mm in histomorphometric examination and zones with histologically different characteristics. Rebleedings from the resection lines were avoided in all cases using the combined CO₂ and Nd:YAG laser.     

Nd:YAG laser versus traditional scalpel. A preliminary histological analysis of specimens from the human oral mucosa

Hyperplastic fibro-epithelial lesions are the most common tumor-like swellings in the mouth. The neodymium yttrium aluminium garnet (Nd:YAG) laser appears to be useful for the surgical treatment of these lesions. Some controversies of laser surgery concern the accuracy of pathological diagnosis as well as the control of thermal damage on the target tissue. The aim of this study was to establish if the thermal changes induced by the Nd:YAG laser may affect the histopathological diagnosis and the evaluation of the resection margins. Furthermore, we compared the histological features of oral benign fibro-epithelial lesions excised through Nd:YAG laser and traditional scalpel. Twenty-six benign fibro-epithelial oral lesions from 26 patients, localized in the same oral subsites (cheek and buccal mucosa), were collected at the Unit of Oral Pathology and Oral Laser-assisted Surgery of the Academic Hospital of the University of Parma, Italy. Specimens were subclassified into three groups according to the tool used for the surgical excision. Group 1 included six specimens excised through Nd:YAG laser with an output power of 3.5 W and a frequency of 60 Hz (power density 488,281 W/cm²); Group 2 included nine specimens excised through Nd:YAG laser with an output power of 5 W and a frequency of 30 Hz; Group 3 included 11 specimens excised through a Bard-Parker scalpel blade no. 15c. Epithelial changes, connective tissue modifications, presence of vascular modifications, incision morphology and the overall width of tissue modification were evaluated. Differences between specimens removed with two different parameters of Nd:YAG laser were not significant with regard to stromal changes (p = 0.4828) and vascular stasis (p = 0.2104). Analysis of regularity of incision revealed a difference which was not statistically significant (p = 1.000) between group 1 and group 2. Epithelial and stromal changes were significantly more frequent in specimens with a mean size less than 7 mm (p < 0.0001). Nd:YAG laser induced serious thermal effects in small specimens (mean size less than 7 mm) independently from the frequency and power employed. The quality of incision was better and the width of overall tissue injuries was less in the specimens obtained with higher frequency and lower power (group 1: Nd:YAG laser at 3.5 W and 60 Hz).     

Soft tissue studies with 805 nm diode laser radiation: Thermal effects with contact tips and comparison with effects of 1064 nm Nd:YAG laser radiation

This study compares the perioperative depths of thermal coagulation, charring, and incision in rabbit liver, internal anterior abdominal wall skeletal muscle, and abdominal skin and in swine liver and abdominal skin obtained with 805 nm diode laser and 1,064 nm Nd:YAG laser radiation using 300-μm-diameter conicaltip and 1,200-μm-diameter spherical-tip contact fibers by hand. Additionally, the total depth of tissue necrosis surrounding incisions made with both lasers and contact tips is determined 48 hours postoperatively in the three tissues, and healing of the liver and abdominal wall muscle 21 and 35 days postoperatively is assessed histologically. Perioperatively determined charring, coagulation, and incision depth obtained in all tissues with either 805 nm or 1,064 nm laser radiation were sensibly equivalent at equal laser power values for each of the two contact tip shapes tested. At equal laser power values, coagulation depths obtained in rabbit abdominal skin using the 300-μm-diameter conical tip differed significantly (P ? 0.01) from those values obtained with the 1,200-μm-diameter spherical tip. Incision depths obtained with the two different contact tip shapes at equal laser power settings in the different tissues studied differed in a few instances with no apparent pattern relating to tissue type or laser power. Depth of incisions obtained with both laser and tip types increases in the range of 6–12 w, but plateaus in the range 12–18 w in the tissues studied. Incisions obtained with both diode and Nd:YAG laser contact were essentially hemostatic, with self-limiting oozing at most. Tissue necrosis examined at 48 hours showed invasion of inflammatory cells in liver, abdominal skeletal muscle, and skin; 21 and 35 days postoperatively, histology samples of liver and skeletal muscle showed healing with normal fibrous tissue deposition. Results of this study support the essential equivalency of tissue thermal effects obtained with the 805 nm diode and Nd:YAG lasers in the contact mode and support the use of the diode laser as an alternative medical laser. © 1993 Wiley-Liss, Inc.     

Optical properties of human articular tissue as implication for a selective laser application in arthroscopic surgery

Background and Objective: Optical density of normal and pathological hyaline cartilage, meniscus, and synovium is determined using native and laser-irradiated tissue samples in order to examine potentials for a selective laser ablation. Study Design/Materials and Methods: One hundred forty-four autopsy specimens were irradiated in a direct contact mode using a XeCl excimer laser (λ = 308 nm; 20 ns; 40 Hz; 40 ± 2.1 J/mm²; 800 μm fused silica fiber) and a continuous-wave Nd:YAG laser (λ = 1,064 nm; 1 s; 124 ± 5.4 W/mm²; 600 μm fused silica fiber). Transmission spectra were obtained by microspectrophotometry in a spectral range from 250 to 770 nm. Results: In the ultraviolet spectrum analyzed, optical density (OD) is calculated to 0.81 ± 0.05 for native hyaline cartilage, to 1.0 ± 0.07 for meniscal tissue, and to 0.68 ± 0.04 for synovium. With increasing wavelength the OD steadily decreases reaching mean values of 0.06 ± 0.01, 0.13 ± 0.03, and 0.15 ± 0.04 at 750 nm. Compared to normal tissue degeneration of cartilage and meniscus lead to a significant increase in OD with a maximum relative OD of 4.39 and 1.26, respectively (P <.001 and P <.01). In synovitis the OD increases with a maximum ratio of 1.45:1 (P <.01). Following Nd:YAG laser exposition the OD of the coagulated zone exceeded the value of native tissue by a factor of 9.71 for cartilage, 4.71 for meniscus, and 3.04 for synovium (P <.001). Excimer irradiation leads to a 3.38-fold increase in OD for cartilage, 2.23-fold for meniscal tissue, and 1.6-fold for synovium (P <.01). Conclusion: The results presented indicate that a preferential ablation of pathological tissue structures in articular surgery is possible by selecting laser systems with an appropriate spectral emission range. However, thermal laser tissue interaction may lead to severe alterations in optical properties reducing potentials of a preferential or selective laser application. © 1995 Wiley-Liss, Inc.