Advanced Interventions Dr. Coenraad Frederik Nicolaas Koegelenberg Stellenbosch University 7602 Cape Town SOUTH AFRICA coeniefn@sun.ac.za AIMS Optimisation of patient positioning prior to and safety during ultrasound-guided procedures Appreciation of the general technical factors and practical aspects involved with ultrasound guidance Provide an overview of the indications and evidence base for ultrasound-guided pleural, pulmonary and other related biopsies Introduce other indications for ultrasound guidance, including tube thoracostomy insertion and medical thoracoscopy SUMMARY Introduction There are many advantages of using transthoracic ultrasound (TUS) as a guide for invasive procedures, including the decreased risk of complications, increased diagnostic yield, and convenience, as both imaging and procedure can be performed by a single operator at the bedside.(1,2) Further advantages are the cost saving and reduction in ionising radiation, when compared to CT scanning. Patient factors The optimal patient position for performing TUS and the subsequent planned intervention is important yet often underappreciated. Ultrasonographic visualisation of the chest contents can usually only be achieved through the intercostal spaces, the supraclavicular fossae and the upper abdomen. Critical care and emergency medicine physicians usually scan acutely ill patients in the supine position and evaluate eight chest areas utilising the well-known E-FAST method.(3) In contrast, the respiratory physician uses TUS as an adjunct to clinical assessment and routine radiology prior to transthoracic interventions. A patient s chest radiograph and CT scan frequently identify the area of interest, and thereby provide guidance for the optimal positioning of the patient.(2) The posterior chest is best scanned with patient in a sitting position using a bedside table as an armrest, or alternatively sitting backwards on a chair and leaning forward against the back of the chair. The lateral and anterior chest wall can be examined with the patient in either the lateral decubitus or supine position and superior sulcus pathology can be visualised apically with the patient in the supine or sitting position. Many clinicians hold the transducer in a longitudinal (vertical) plane with the transducer indicator in a cephalad position. Although, this technique has some advantages (e.g. potentially greater sensitivity for detecting pneumothoraces), superior visualisation of the pleura and peripheral lung tumours can be achieved by positioning the transducer parallel to the intercostal spaces. Interventionists, therefore, often utilise this technique. Patient safety is important. The main viscera, diaphragm and major blood vessels should be clearly visualised. The intercostal arteries generally run below the rib in the sub-costal groove.(4) The first few centimetres lateral to the spine often exposes the artery within the intercostal space. The variability of its position increases with age and a more cephalic intercostal spaces, and a lateral approach is therefor generally safer.(5) Colour flow Doppler can be used to identify intercostal
arteries, but it may be challenging as it produces artefact with respiratory movement. Further assessment is required before wider clinical use given its apparent poor negative predictive value.(6) General Technical Aspects Ultrasound-guided procedures can either be performed by freehand or real-time.(2) The freehand technique involves accurately visualising and identifying the area of interest and marking the overlying skin. Both the optimal depth and safety range should be noted. The procedure is then performed in the correct plain and at the appropriate depth without repositioning the patient. Patients are sometimes asked to hold their breath. Real-time guided procedures can be performed either in-plane of the ultrasound or out-ofplane. Reusable probes designed for real-time guidance are commercially available, and are often combined with disposable biopsy needles. Using the in-plane (long axis) approach, the needle enters the skin at the side of the probe, and traverses the plane of ultrasound with the whole shaft (seen as a large needle artefact) being visualised in the tissue. For the out-of-plane (short axis) approach, the needle enters the skin away from the probe, and is aimed at the plane of sound. Only the needle tip is visualised while the remainder of the needle is off screen. At the end of the procedure, ultrasound remains a validated screening method for post-procedural pneumothoraces. Image-Guided Pleural Biopsy Blind closed pleural biopsy is prone to sampling error, and has a sensitivity for diagnosing malignancy of 48-56%. Medical thoracoscopy was therefore traditionally preferred as first line investigation for undiagnosed pleural exudates.(7) Image guidance has been shown to increase the likelihood of obtaining pleural tissue independent of pleural thickening. Both CT and TUS guidance can be utilised, with the latter having the advantage of being mobile.(8) There is no convincing evidence to suggest that CT guidance is superior, while TUS guidance allows for the biopsy of overtly abnormal pleura. TUS allows the operator to target biopsy sites close the diaphragm where malignant deposits are more frequently located. Thus TUS guidance decreases the risk of visceral lacerations and allows the use of other devices, e.g. Tru-Cut and safe biopsy of dry mesotheliomas.(8,9) Using TUS-guidance, the diagnostic yield for malignancy is in the order of 77-90%, and even as high as 100% for mesothelioma (>3 cm).(10) The TUS-guided biopsies are more likely to be diagnostic if at least 6 specimens are taken and where pleural thickening is >10mm, or where there is pleural nodularity or solid pleural tumours.(8) Ultrasound-guided pleural biopsy has a diagnostic yield of up to 90% for pleural tuberculosis, which is not surprising given the diffuse nature of the disease.(8) Some centres prefer to use the Tru-Cut needle biopsies over the more conventional Abrams needle. Current evidence however, still favours the use of the Abrams needle. One study found a greater overall diagnostic yield of 79% for the Abrams needle compared with 63% for the Tru-cut needle.(11) Assessment of the initial imaging can be used to decide with procedure to perform. Patients can be divided into those with: (i) a mass lesion with an interface of at least 1 cm in two dimensions; (ii) diffuse pleural thickening (>10 mm) and/or nodularity; or (iii) insignificant pleural thickening.(7,8) Pleural based masses are ideally suited for TUS-guided transthoracic fine needle aspiration (TTFNA), preferably with rapid on-site evaluation (ROSE). TUS-guided cutting needle biopsy (CNB) is performed if no diagnostic material can be confirmed on ROSE. In the absence of a pleural based mass lesion, the choice of biopsy device and technique is best guided by the clinical setting. If the pretest probability for TB is high, an Abrams needle should be utilised (irrespective of pleural
thickening), and imaging should be used to improve safety. In the presence of pleural thickening or nodularity, TUS-guided biopsy with either Tru-cut or Abrams needle in the area of interest should be performed. In the absence of overt pleural abnormalities, a low supradiaphragmatic biopsy with an Abrams needle is suggested, as it is more likely to harvest pleura. A recent study confirmed the utility of this approach, yielding a 90% diagnostic yield in previously undiagnosed pleural exudates.(12) Image-Guided Lung Biopsy Pulmonary masses are only detectable if there is pleural contact present. In this setting TUS-guided biopsy is considered safe, as no aerated lung is traversed.(13) Because of rib shadows, the acoustic window is too narrow to demonstrate the whole mass circumference, but TUS allows accurate assessment of its depth. The diagnostic yield of TUS-guided pulmonary biopsy is 89%. TTFNA has a higher sensitivity than CNB in diagnosing lung cancer (95% vs. 81%), whereas CNB is superior in non-carcinomatous tumours and benign pathology.(13) The pleural contact length also influences diagnostic yield.(14) Pneumothoraces are observed in 1.3% of cases undergoing TTFNA and 4% of cases with CNB.(13) With peripheral lung lesions, TUS-guidance is comparable to CT-guidance in terms of sample accuracy, but has the benefits of a reduced procedure time and pneumothorax rate.(15) Other Image-Guided Chest Biopsies Chest wall masses are well suited for transthoracic ultrasound-assisted biopsy, as the pleural space and chest cavity is not breached. The diagnostic yield is comparable to TUS-guided pulmonary biopsy.(7) TUS-guided biopsy of mediastinal masses offers a significantly less invasive, safer and cheaper alternative to mediastinoscopy or mediastinotomy.(16) Prospective data showed that 93% of patients with an anterior mediastinal mass could be diagnosed in a single-session with TUS-guided biopsy.(16) Cervical, supraclavicular and axillary lymph nodes are accessibly by means of TUS-guided biopsy. Malignant nodes appear bulky, with a hypoechoic appearance and irregular borders. FNA of supraclavicular lymph nodes is standard practice in many institutions. It has the advantage of providing cytological diagnosis and pathological staging (pn3) in one, minimally invasive procedure.(17) Role of TUS in Tube Thoracostomy Similar to biopsies, TUS-guided intercostal drain (ICD) insertions can either be performed freehand or real-time. With the free-hand technique the site should be in an area that contains the largest amount of pleural fluid. Care should be taken to avoid mobile structures such as the lung, diaphragm and heart during the respiratory cycle. The distance between the skin and parietal pleura, and between the parietal pleura and lung / diaphragm should be noted (and an image saved). TUS may also be utilised to place the guidewire under direct vision ( real-time insertion) such as the modified Seldinger technique to insert a small bore drain (once guidewire is in situ).(18) This technique is less painful, and as effective as large bore drains.(19) Ultrasound and Medical Thoracoscopy TUS is a very useful adjunct to thoracoscopy, as it allows real-time assessment of the nature of the pleural space. In the presence of a pleural effusion, TUS is performed on the table and with the patient
positioned for the procedure. The space is evaluated throughout the respiratory cycle, and the ideal space for Trocar insertion is identified. TUS is more accurate than CT at identifying pleural thickening, adhesions and loculations / septae.(20) It is important to also identify diaphragm, liver / spleen and lung, to prevent injury. Medical thoracoscopy has traditionally not been performed in the absence of an effusion. However, in suitable cases (e.g. with lung sliding in the mid-axillary line), a 16-gauge needle under direct TUS guidance with an in-plane approach can be used to successfully introduce air into the pleural space. This approach has been shown to be successful in 96% of cases with clear lung sliding, and is also considered safe.(21) Conclusions TUS is the ideal guide for transthoracic diagnostic and therapeutic procedures. The optimal patient position for scanning and the subsequent interventions is important. The main viscera, diaphragm, major blood vessels and, when appropriate, the intercostal arteries are readily visualised. TUS-guided procedures can either be performed freehand or real-time. TUS-guided pleural, chest wall, pulmonary, mediastinal and peripheral lymph node biopsy has a high diagnostic yield, is safe and can avert the need for more invasive and expensive investigations. TUS should be used as a guide to all ICD insertions. During medical thoracoscopy, TUS allows for safe insertion of the trocar, and even enables clinicians to perform thoracoscopy in the absence of an effusion. REFERENCES 1. Havelock T, Teoh R, Laws D, Gleeson F. Pleural procedures and thoracic ultrasound: British Thoracic Society Pleural Disease Guideline 2010. Thorax. 2010;65(Suppl 2):ii61 76. 2. Koegelenberg CFN, Von Groote-Bidlingmaier F, Bolliger CT. Transthoracic ultrasonography for the respiratory physician. Respiration. 2012;84(4):337-50. 3. Volpicelli G, Elbarbary M, Blaivas M, Lichtenstein D, Mathis G, Kirkpatrick A, et al. International evidence-based recommendations for point-of-care lung ultrasound. Intensive Care Med. 2012;38(4):577-91. 4. Tobin CL. Image Interpretation: Normal Ultrasound of the Chest. In: Tobin CL, Gleeson F, Rahman N, Feller-Kopman D, editors. Pleural Ultrasound for Clinicians. Boca Raton: CRC Press; 2014. p. 47-58. 5. Corcoran J, Psallidas I, Wrightson J, Hallifax R, Rahman N. Pleural procedural complications: prevention and management. J Thorac Dis. 2015;7(6):1058 67. 6. Salamonsen M, Dobeli K, McGrath D, Readdy C, Ware R, Steinke K, et al. Physician-performed ultrasound can accurately screen for a vulnerable intercostal artery prior to chest drainage procedures. Respirology. 2013;18(6):942-7. 7. Koegelenberg CFN, Diacon AH. Closed needle pleural biopsy or thoracoscopy Which first? Respirology. 2011;16(5):738 46. 8. Koegelenberg CFN, Diacon AH. Image-guided pleural biopsy. Curr Opin Pulm Med. 2013;19(4):368-73. 9. Stigt JA, Boers JE, Groen HJM. Analysis of dry mesothelioma with ultrasound guided biopsies. Lung Cancer;78(3):229-33. 10. Azzopardi M, Porcel J, Koegelenberg C, Lee Y, Fysh E. Current controversies in the management of malignant pleural effusions. Semin Respir Crit Care Med. 2014;35(6):723 31. 11. Koegelenberg CFN, Bolliger CT, Theron J, Walzl G, Wright CA, Louw M, et al. Direct comparison of the diagnostic yield of needle biopsies for pleural tuberculosis Direct comparison of the diagnostic yield of ultrasound-assisted Abrams and Tru-Cut needle biopsies for pleural tuberculosis. Thorax. 2010; 65(10):857-62 12. Koegelenberg C, Irusen E, von Groote-Bidlingmaier F, Bruwer J, Batubara E, Diacon A. The utility of ultrasound-guided thoracocentesis and pleural biopsy in undiagnosed pleural exudates. Thorax. 2015; 70:995-7
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