an Observational Study Evaluting the Effectiveness and Safety of DKutting LL Noval Scoring Balloon Angioplasty for Vessel Preparation Facilitated by IVUS on the Lower Limb Ischemia Patients With Calcified Lesions

Inclusion Criteria: * Age ≥ 18 years and ≤ 85 years. * Clinical diagnosis of lower extremity atherosclerotic arterial disease, with a Rutherford Classification of Category 2-5. * The patient has provided written informed consent. * Life expectancy \> 1 year. * Confirmed by clinical and CTA examination: de novo or restenotic lesions after PTA in the femoropopliteal or infrapopliteal arteries, with no stent implantation within 2 cm of the target lesion. Stenosis ≥70% or chronic total occlusion (CTO). * Lesion confirmed by CTA and color Doppler to have moderate to severe calcification (PACSS Grade 3-4). Lesion can be single or tandem, with a total length ≤150 mm. Reference vessel diameter near the target lesion ≥2 mm. * Allowable location of the target lesion: ≥1 cm distal to the common femoral artery bifurcation, and up to 10 cm above the ankle. * If the lesion is below-the-knee (BTK), the inflow vessels must have no non-target lesions, or any non-target lesions must be successfully treated with the current device without vascular complications. * No serious vascular complications such as flow-limiting dissection occur after pre-dilation of the target lesion. * Presence of at least one reconstructible infrapopliteal runoff vessel patent to the ankle. Exclusion Criteria: * Allergy to contrast media. * Coagulopathy; severe hepatic insufficiency (ALT or AST \> 3 times the upper limit of normal). * Cardiac insufficiency (New York Heart Association Class III-IV). * Life expectancy \< 1 year. * Acute cardiovascular events (e.g., acute myocardial infarction, stroke) within the past 3 months; active gastrointestinal bleeding affecting the use of anticoagulant/antiplatelet therapy. * Previous stent implantation or bypass surgery in the target vessel. * Acute/subacute limb ischemia or thrombotic lesions. * Contraindications to anticoagulation or antiplatelet therapy. * Failure to cross the lesion with a guidewire during the procedure; anticipation that the IVUS catheter or DKutting balloon will be unable to cross the lesion after pre-dilation. * Intraoperative occurrence of severe complications requiring conversion to other treatment methods (e.g., bypass surgery). * Pregnant or lactating women. * Active infection at the intended treatment site; foot wounds reaching WIfI Stage 3, or ankle/foot ulcers primarily of non-ischemic etiology. * Patient withdrawal of informed consent. * Planned amputation. * Planned use of adjunctive therapy devices (e.g., atherectomy, laser). * Participation in another interventional drug/device clinical study for lower limb arteries where the primary endpoint has not been reached, or planned participation in such a study. * Patient is bedridden or unable to walk. * Presence of an aneurysm in the ipsilateral limb vasculature.