title: Prognostic factors influencing the development of an iatrogenic pneumothorax for computed tomography-guided radiofrequency ablation of upper renal tumor.
abstract: BACKGROUND
  Percutaneous radiofrequency (RF) ablation of upper renal tumors is considered a minimally invasive treatment, but this technique may cause pneumothorax.
  
  
  OBJECTIVE
  To assess retrospectively the prognostic factors influencing the development of iatrogenic pneumothorax for RF ablation of upper renal tumors.
  
  
  METHODS
  Computed tomography (CT)-guided RF ablation was performed in 24 patients (21 men, three women; age range 31-77 years, mean age 53.3 years) with 28 upper renal tumors. Various factors for pneumothorax-complicated (PC) upper renal tumors and non-pneumothoracic (NP) upper renal tumors were compared during RF ablation to determine which of the factors were involved in the development of pneumothorax.
  
  
  RESULTS
  Among 28 upper renal tumors in 24 patients, a pneumothorax occurred accidentally in six patients with eight tumors and intentionally in two patients with two tumors. This complication was treated with conservative management, instead of tube drainage. PC upper renal tumors had shorter distance from the lung or from the costophrenic line to the tumor, a larger angle between the costophrenic line and the tumor, and a higher incidence of intervening lung tissue than NP upper renal tumors (P<0.01). Intervening lung tissue was more frequently detected on CT images obtained with the patient in the prone position than on CT images obtained with the patient in the supine position.
  
  
  CONCLUSIONS
  The presence of intervening lung tissue and the close proximity between an upper renal tumor and the lung are high risk factors for developing an iatrogenic pneumothorax. Pre-ablation CT scan should be performed in the prone position to exactly evaluate intervening lung tissue.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. rapark@skku.edu
authors.forename: B K
authors.initials: BK
authors.lastname: Park
authors.forename: C K
authors.initials: CK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D003287:Contrast Media; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007049:Iatrogenic Disease; D007680:Kidney Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects / Q000379:methods; D011030:Pneumothorax / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy; D011379:Prognosis; D016684:Prone Position; D011856:Radiographic Image Enhancement / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors; D016683:Supine Position; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media