the advent of endobronchial ultrasound ( ebus ) has widened the horizons for an intervention pulmonologist . while convex or linear probe ebus enables sampling of the mediastinal and hilar lymph nodes , the use of radial probe ebus helps in the biopsy of peripherally located lesions . the use of radial probe ebus to visualize and biopsy the peripheral pulmonary opacities was first described in 1992 by hurter et al . subsequently , the technique was systematically studied by herth et al . and kurimoto et al . without and with the guide sheath method , respectively to sample the peripheral pulmonary lesions ( ppl ) . further , various sonographic patterns were described on radial ebus to distinguish benign from malignant diseases . radial probe ebus consists of an ultrasound probe transducer that has a frequency of 20 - 30 mhz and a scanning view of 360 degrees . the tissue penetration of the radial probe ebus is 4 - 5 cm and provides good quality images . based on internal morphology , vascular and bronchial patency , and internal echoes on ebus images , the lesions can be divided into three types ( type i , homogenous pattern ; type ii , hyperechoic dots and linear arcs ; and type iii , heterogeneous pattern ) . herein , we describe two cases that were successfully diagnosed with the use of radial probe ebus . to the best of our knowledge this is the first report on the use of radial probe ebus in the diagnosis of peripheral lung lesions from the indian subcontinent . a 62-year old lady presented with history of dry cough of one - month duration . there was no history of fever , chest pain , breathlessness , hemoptysis and loss of weight or appetite . a solitary pulmonary nodule ( 2  3 cm ) was detected in the right upper zone [ figure 1 ] that was subsequently confirmed on contrast enhanced computed tomography ( ct ) of the thorax [ figure 1 ] . a radial probe guided biopsy was planned to evaluate the etiology of the pulmonary nodule . the procedure was performed under local anesthesia and conscious sedation using fluoroscopy in the bronchoscopy suite of the department , as previously described . a flexible bronchoscope ( bf-1t20 , olympus , japan ) was introduced through the nasal route and the airway anatomy was visualized . after ruling out any endobronchial abnormality , a radial probe transducer ( 20 mhz , mechanical - radial type , [ um - s20 - 20r ; olympus , tokyo , japan ] ) with an outer diameter of 17 mm covered with the guide sheath ( sg-200c [ inner diameter 20 mm ] ; olympus , tokyo , japan ) was introduced through the working channel of the flexible bronchoscope . the probe was connected to an endoscopic ultrasound system ( eu - m30 ; olympus , tokyo , japan ) . the guide sheath has a length of 105 cm and the length of the radial probe transducer is 115 cm . the position of the radial probe was adjusted ex - vivo such that only the tip of the transducer protruded out of the guide sheath and the position was secured with a locking mechanism . the length of various instruments such as biopsy brush ( bc-202d-5010 ; olympus , tokyo , japan ) , and biopsy forceps ( fb-233d ; olympus , tokyo , japan ) was also secured in a similar fashion . after clearing the airways of secretions , the transducer probe was pushed forwards such that only the tip was visualized . the probe and sheath was then introduced to the selected segment until the resistance was felt and the probe could not be pushed any further . the radial probe - sheath assembly was then withdrawn slowly towards the operator until either an abnormality was identified or the probe - sheath assembly was visualized outside the chosen segment . if the lesion could not be identified in the selected segment the probe - sheath assembly was introduced into another segment . once the lesion was identified [ figure 2 ] , the transducer was then withdrawn and the guide sheath was left in situ . bronchial brushing , bronchial washing and transbronchial biopsy were then performed through the guide sheath . the patient underwent whole body positron emission tomography ( pet ) ct , which revealed a 2.1  1.6  1.6 cm soft tissue density with maximum standardized uptake value ( suv max ) of 7.1 involving the right upper lobe bronchus with no evidence of secondaries . a final diagnosis of adenocarcinoma of the lung stage ib was made . surgical lung biopsy specimen revealed adenocarcinoma of the lung with free resection margins ; the mediastinal lymph nodes were free of tumor cells . chest radiograph ( right panel ) showing a solitary pulmonary nodule ( arrow ) , which is also visualized on computed tomography of the chest ( left panel ) radial probe endobronchial ultrasound image showing heterogeneous area with multiple hyperechoic shadows a 29-year old gentleman presented with history of intermittent hemoptysis of one - month duration . about one - and - a - half years ago , he was diagnosed as pulmonary tuberculosis , based on the presence of fever , weight - loss , cough and positive sputum smear for afb . he was treated with six months of anti - tuberculosis therapy and was declared cured . a chest radiograph performed during current illness revealed a solitary nodule in the left upper zone region . contrast enhanced ct of the thorax revealed a small nodule measuring 2.0  1.5 cm in the lingula [ figure 3 ] . sputum smear for afb , xpert mtb / rif , cytology , and culture for mycobacteria and fungi were all negative . subsequently , a radial probe ebus was performed as described above and the lesion was sampled by bronchial washing , brush cytology and transbronchial lung biopsy . patient was managed conservatively with tranexamic acid alone for hemoptysis . on follow - up at six months , the patient continues to do well and has not had any further episode of hemoptysis . contrast enhanced computed tomography of the chest showing a small nodule measuring 2.0  1.5 cm in the lingual a 62-year old lady presented with history of dry cough of one - month duration . there was no history of fever , chest pain , breathlessness , hemoptysis and loss of weight or appetite . a solitary pulmonary nodule ( 2  3 cm ) was detected in the right upper zone [ figure 1 ] that was subsequently confirmed on contrast enhanced computed tomography ( ct ) of the thorax [ figure 1 ] . a radial probe guided biopsy was planned to evaluate the etiology of the pulmonary nodule . the procedure was performed under local anesthesia and conscious sedation using fluoroscopy in the bronchoscopy suite of the department , as previously described . a flexible bronchoscope ( bf-1t20 , olympus , japan ) was introduced through the nasal route and the airway anatomy was visualized . after ruling out any endobronchial abnormality , a radial probe transducer ( 20 mhz , mechanical - radial type , [ um - s20 - 20r ; olympus , tokyo , japan ] ) with an outer diameter of 17 mm covered with the guide sheath ( sg-200c [ inner diameter 20 mm ] ; olympus , tokyo , japan ) was introduced through the working channel of the flexible bronchoscope . the probe was connected to an endoscopic ultrasound system ( eu - m30 ; olympus , tokyo , japan ) . the guide sheath has a length of 105 cm and the length of the radial probe transducer is 115 cm . the position of the radial probe was adjusted ex - vivo such that only the tip of the transducer protruded out of the guide sheath and the position was secured with a locking mechanism . the length of various instruments such as biopsy brush ( bc-202d-5010 ; olympus , tokyo , japan ) , and biopsy forceps ( fb-233d ; olympus , tokyo , japan ) was also secured in a similar fashion . after clearing the airways of secretions , the transducer probe was pushed forwards such that only the tip was visualized . the probe and sheath was then introduced to the selected segment until the resistance was felt and the probe could not be pushed any further . the radial probe - sheath assembly was then withdrawn slowly towards the operator until either an abnormality was identified or the probe - sheath assembly was visualized outside the chosen segment . if the lesion could not be identified in the selected segment the probe - sheath assembly was introduced into another segment . once the lesion was identified [ figure 2 ] , the transducer was then withdrawn and the guide sheath was left in situ . bronchial brushing , bronchial washing and transbronchial biopsy were then performed through the guide sheath . the patient underwent whole body positron emission tomography ( pet ) ct , which revealed a 2.1  1.6  1.6 cm soft tissue density with maximum standardized uptake value ( suv max ) of 7.1 involving the right upper lobe bronchus with no evidence of secondaries . a final diagnosis of adenocarcinoma of the lung stage ib was made . surgical lung biopsy specimen revealed adenocarcinoma of the lung with free resection margins ; the mediastinal lymph nodes were free of tumor cells . chest radiograph ( right panel ) showing a solitary pulmonary nodule ( arrow ) , which is also visualized on computed tomography of the chest ( left panel ) radial probe endobronchial ultrasound image showing heterogeneous area with multiple hyperechoic shadows a 29-year old gentleman presented with history of intermittent hemoptysis of one - month duration . about one - and - a - half years ago , he was diagnosed as pulmonary tuberculosis , based on the presence of fever , weight - loss , cough and positive sputum smear for afb . he was treated with six months of anti - tuberculosis therapy and was declared cured . a chest radiograph performed during current illness revealed a solitary nodule in the left upper zone region . contrast enhanced ct of the thorax revealed a small nodule measuring 2.0  1.5 cm in the lingula [ figure 3 ] . sputum smear for afb , xpert mtb / rif , cytology , and culture for mycobacteria and fungi were all negative . subsequently , a radial probe ebus was performed as described above and the lesion was sampled by bronchial washing , brush cytology and transbronchial lung biopsy . patient was managed conservatively with tranexamic acid alone for hemoptysis . on follow - up at six months , the patient continues to do well and has not had any further episode of hemoptysis . contrast enhanced computed tomography of the chest showing a small nodule measuring 2.0  1.5 cm in the lingual the index cases highlight the diagnostic performance of radial probe ebus in the evaluation of ppl . until recently , ct - guided needle aspiration or biopsy , surgical lung biopsy or video - assisted thoracoscopic surgery formed the procedure of choice in the assessment of ppl . the surgical procedures are invasive and require general anesthesia and hospitalization while the performance of ct - guided procedures is associated with high risk of pneumothorax and exposure to radiation . the risk of pneumothorax ranges from 9% to as high as 64% in ct - guided sampling of thoracic lesions . this risk is higher in the presence of chronic obstructive pulmonary disease , small lesion size , greater lesion depth , needle trajectory angle of < 45 degrees , and repeated pleural punctures . in a recent comparative study between ct - guided biopsy versus radial probe guided biopsy , the radial probe ebus - guided arm had had a similar diagnostic accuracy ( 93.3% vs. 87.5% ) but with a significantly lower incidence of pneumothorax ( 27% vs. 3% ) . the first series of radial probe ebus included 50 patients with ppl who underwent transbronchial lung biopsy under both fluoroscopic guidance and radial ebus . the diagnostic accuracy for radial ebus was similar to fluoroscopy - guided biopsy ( 80% vs. 76% ) ; however , there was a trend towards better diagnostic yield with radial ebus in lesions measuring less than 3 cm . in a subsequent study using the guide - sheath method , the radial ebus was diagnostic in 77% of the procedures performed . in lesions measuring 10 mm , radial ebus with in a recent meta - analysis ( 16 studies ) , the sensitivity and specificity of radial probe ebus for sampling the peripheral lung nodules / masses was 0.73 and 1.00 , respectively in the detection of lung cancer . in the index cases , the size of the lesions varied from 20 - 30 mm and were located atleast 3 cm away from the chest wall . we combined bronchial washing , brush sampling and transbronchial lung biopsy in both our patients . combining all three methods increases the diagnostic yield of radial ebus , when compared with either of the procedure performed alone . in a study involving 196 consecutive patients who underwent radial ebus , the diagnosis was confirmed in 55.6% of patients ( 109/196 ) from a combination of washings ( 63/190 ) , brushing ( 74/153 ) and transbronchial biopsy ( 79/149 ) . several factors affect the diagnostic yield of radial ebus with a higher yield observed in cases with malignant etiology , distance from hilum < 50 mm , size of the lesion > 3 cm , end - on bronchus sign on ct , use of guide sheath method , position of the probe within the lesion , number of biopsies performed and others . in both of our cases , the lesion was visualized on ebus , and we performed at least six biopsies in both of our patients and used the guide sheath method . the use of guide sheath method ensures reproducibility of the sampling and the target area can be sampled repeatedly as the position of the sheath is secured . this is unlike ct - guided fnac , where the position has to be reconfirmed after each pass , and changes with the respiratory movement . although , studies have shown that the diagnostic yield of radial ebus is not affected by the use of fluoroscopy , we chose to use fluoroscopy due to the initial learning curve and the time needed to acquire the skill in performing radial ebus . it has been shown that lesions can be sampled successfully using radial ebus , even if they are not visualized on fluoroscopy . this is further supported by a meta - analysis of sixteen studies where the use of fluoroscopy did not affect the diagnostic yield of radial ebus . the use of radial ebus is safe and the only complications are minor bleeding and pneumothorax . in a pooled analysis of sixteen studies , the complication rates varied from 0 - 7.4% . the pooled rate of pneumothorax was 1% ( 11 of 1,090 ) , with the rate of intercostal tube drainage being 0.4% . in the current report , we did not encounter any complication while performing radial probe ebus . in conclusion , the use of radial probe ebus can safely and effectively allow the sampling of peripheral pulmonary lesions .
radial probe endobronchial ultrasound ( ebus ) helps in the evaluation and sampling of peripheral pulmonary lesions ( nodules , masses , consolidation ) , and has been demonstrated a safer alternative to computed tomography guided procedure , especially in lesions that are away from the chest wall . 
 although radial probe ebus has been available for more than two decades , there is no report from the indian subcontinent . 
 herein , we describe two cases of peripheral lung lesions that were successfully sampled with the use of radial probe ebus .