3D-2D image registration in the presence of soft-tissue deformation in image-guided transbronchial interventions.

Purpose. Target localization in pulmonary interventions (e.g. transbronchial biopsy of a lung nodule) is challenged by deformable motion and may benefit from fluoroscopic overlay of the target to provide accurate guidance. We present and evaluate a 3D-2D image registration method for fluoroscopic overlay in the presence of tissue deformation using a multi-resolution/multi-scale (MRMS) framework with an objective function that drives registration primarily by soft-tissue image gradients.Methods. The MRMS method registers 3D cone-beam CT to 2D fluoroscopy without gating of respiratory phase by coarse-to-fine resampling and global-to-local rescaling about target regions-of-interest. A variation of the gradient orientation (GO) similarity metric (denotedGO') was developed to downweight bone gradients and drive registration via soft-tissue gradients. Performance was evaluated in terms of projection distance error at isocenter (PDEiso). Phantom studies determined nominal algorithm parameters and capture range. Preclinical studies used a freshly deceased, ventilated porcine specimen to evaluate performance in the presence of real tissue deformation and a broad range of 3D-2D image mismatch.Results. Nominal algorithm parameters were identified that provided robust performance over a broad range of motion (0-20 mm), including an adaptive parameter selection technique to accommodate unknown mismatch in respiratory phase. TheGO'metric yielded median PDEiso= 1.2 mm, compared to 6.2 mm for conventionalGO.Preclinical studies with real lung deformation demonstrated median PDEiso= 1.3 mm with MRMS +GO'registration, compared to 2.2 mm with a conventional transform. Runtime was 26 s and can be reduced to 2.5 s given a prior registration within ∼5 mm as initialization.Conclusions. MRMS registration via soft-tissue gradients achieved accurate fluoroscopic overlay in the presence of deformable lung motion. By driving registration via soft-tissue image gradients, the method avoided false local minima presented by bones and was robust to a wide range of motion magnitude.

Technical aspects of endobronchial ultrasound-guided transbronchial needle aspiration: CHEST guideline and expert panel report

BACKGROUND: Endobronchial ultrasound (EBUS) was introduced in the last decade, enabling real-time guidance of transbronchial needle aspiration (TBNA) of mediastinal and hilar structures and parabronchial lung masses. The many publications produced about EBUS-TBNA have led to a better understanding of the performance characteristics of this procedure. The goal of this document was to examine the current literature on the technical aspects of EBUS-TBNA as they relate to patient, technology, and proceduralist factors to provide evidence-based and expert guidance to clinicians. METHODS: Rigorous methodology has been applied to provide a trustworthy evidence-based guideline and expert panel report. A group of approved panelists developed key clinical questions by using the PICO (population, intervention, comparator, and outcome) format that addressed specific topics on the technical aspects of EBUS-TBNA. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion, and well-recognized document evaluation tools were used to assess the quality of included studies, to extract meaningful data, and to grade the level of evidence to support each recommendation or suggestion. RESULTS: Our systematic review and critical analysis of the literature on 15 PICO questions related to the technical aspects of EBUS-TBNA resulted in 12 tatements: 7 evidence-based graded recommendations and 5 ungraded consensus-based statements. Three questions did not have sufficient evidence to generate a statement. CONCLUSIONS: Evidence on the technical aspects of EBUS-TBNA varies in strength but is satisfactory in certain areas to guide clinicians on the best conditions to perform EBUS-guided tissue sampling. Additional research is needed to enhance our knowledge regarding the optimal performance of this effective procedure.(AU)

Role of the Endobronchial Landmarks Guiding TBNA and EBUS-TBNA in Lung Cancer Staging.

Background. Lung cancer is the leading cause of malignancy related mortality in the United States. Accurate staging of NSCLC influences therapeutic decisions. Transbronchial needle aspiration (TBNA) and endobronchial ultrasound-guided TBNA (EBUS-TBNA) has been accepted as a procedure for the diagnosis and staging of lung cancer. The aim of this study is to evaluate the efficacy and adequacy of TBNA and EBUS-TBNA for sampling of mediastinal adenopathy using the Wang's eleven lymph node map stations. Methods. We retrospectively reviewed 99 consecutive cases diagnosed with malignancy by EBUS-TBNA and a series 74 patients evaluated for mediastinal adenopathy or a pulmonary lesion using conventional transbronchial needle aspiration. The IASLC lymph node map was correlated with Wang's map. Results. A total of 182 lymph node stations were sampled using EBUS-TBNA. 96 were positive for nodal metastasis. A total of four cases of samples taken from station 2R showed malignant cells. From the 74 cases series using cTBNA 167 nodes were sampled in 222 passes. Lymphoid or malignant tissue was obtained in 67 (91.8%) cases; 55.1% of the nodes were 1 cm or less. Conclusions. The use of the eleven stations described in Wang's map to guide TBNA of the mediastinal nodes allows sampling of radiologically considered nonpathological nodes. These data suggest that Wang's map covers the most frequent IASLC nodal stations compromised with metastasis.

The rate of treatment of chronic hepatitis C in patients co-infected with HIV in an urban medical centre.

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection is common. HIV co-infection results in a higher rate of histologic progression and shorter interval to HCV-related cirrhosis. Successful treatment of HCV with interferon-based therapy reduces the morbidity and mortality of patients. Significant factors may limit the availability of treatment in co-infected patients. The rate of treatment of HCV and limiting factors to treatment in a co-infected population in an urban setting were determined. A retrospective review of co-infected patients was conducted at our liver and gastrointestinal (GI) clinics for treatment of HCV from July 2001 to June 2002. Treatment of HCV and reasons for nontreatment were recorded. A total of 104 HCV/HIV co-infected patients were identified. Seventy-two per cent were males. Mean age was 47.2 years (32-72). Seventy-four of the 82 (90%) with identifiable risk factors for HCV infection had a history of intravenous drug use (IVDU). Twenty per cent (21/104) of the total underwent a liver biopsy. Sixty-seven per cent who had a liver biopsy were treated. Overall, sixteen patients were treated. Eighty-eight (85%) patients were not treated for the following reasons: 13 refused treatment, and 75 were ineligible. Of the ineligible patients, 40% were noncompliant with visits, 15% were active substance abusers, 13% had decompensated cirrhosis, 8% had significant active psychiatric conditions and 24% had significant co-morbid disease. A majority of patients co-infected with HCV/HIV had a IVDU history. Most co-infected patients were not eligible for HCV treatment. A majority of noncandidates had potentially modifiable psychosocial factors leading to nontreatment.