A review of lymphoscintigraphy - what constitutes a positive result and how this affects the patients management.

Transcription

1 A review of lymphoscintigraphy - what constitutes a positive result and how this affects the patients management. Poster No.: C-1030 Congress: ECR 2014 Type: Educational Exhibit Authors: N. J. Ley, E. Lorenz, J. Taylor, J. Harding; Sheffield/UK Keywords: Lymph nodes, Nuclear medicine, Oncology, Nuclear medicine conventional, Education, Radiobiology, Haemodynamics / Flow dynamics DOI: /ecr2014/C-1030 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 15

2 Learning objectives To review the use of lymphoscintigraphy in our institution detailing the Indications Methods Examples of different results Clinical implications of a positive result. Page 2 of 15

3 Background Introduction: Lymphoedema is a chronic condition that can have serious physical and psychological implications for patients and early recognition increases the likelihood of successful treatment. Diagnosis is often clinical, however it is important to establish a diagnosis in ambiguous cases before instituting a lifetime management plan. The Lymphatic System Is a complex circulatory system in the body. It consists of 2 broad parts which are: Lymphoid tissue, such as bone marrow and thymus the main role of which is in the generation of lymphocytes. Lymph conducting system formed from lymph vessels, capillaries and nodes, the main role of which is transportation of the lymph around the body and it is this conducting system that lymphoscintigraphy is assessing. (Fig 1)[i] on page Lymphoedema Lymphoedema results from obstruction or impaired flow of the lymph channels. It is characterised by accumulation of subcutaneous fluid most commonly in the limbs but can affect any part of the body and leads to excessive swelling of the affected body part. The condition can lead to distortion in function, size and shape whilst predisposing the patient to infection and long term psychological and social distress. It arises because of failure of the lymphatic system and it can be broadly divided into intrinsic (primary) and extrinsic (secondary) types. Primary Lymphoedema: Is an inherited disorder which is rare and most commonly affects women. It is characterised by a congenital malformation or absence of the lymphatic system and specific causes include Page 3 of 15

4 Milroy's disease which begins in infancy and is caused by a congenital abnormality of the lymph nodes. Meige's disease (Lymphoedema praecox) which can present in infancy or nd rd later in the 2-3 decades and is a result of absent valves in the lymphatic vessels[ii] on page. Secondary Lymphoedema: Is often diagnosed clinically and is a result of damage to the lymphatic system. In the western world the most common causes include malignancy, radiotherapy or surgery. In tropical countries parasitic infection is the main causative agent. Page 4 of 15

5 Images for this section: Fig. 1: Normal anatomy of the lymph system Page 5 of 15

6 Findings and procedure details Lymphoscintigraphy has become an important tool in making a diagnosis of lymphoedema. It is a safe, minimally-invasive and a well established technique for assessing the lymphatic drainage[iii] on page. Indications: To confirm a diagnosis of Lymphoedema in patients with suspected primary Lymphoedema. In ambiguous cases where patients have also had a subsequent operation/ malignancy that is masking a diagnosis or primary Lymphoedema. Secondary lymphoedema is usually diagnosed clinically unless it is an unusual presentation in which clinical findings could be used in conjunction with a lymphoscintigraphy study to establish a diagnosis of underlying primary lymphoedema. It is important to establish a diagnosis of primary lymphoedema as these patients are younger and require higher compression to control their symptoms. A confirmed diagnosis may also help them cope with the psychological and social implications of the condition. In ambiguous cases it is important to establish the diagnosis to exclude a different, treatable cause of the limb swelling for example cellulitis, and also to ensure that new onset leg swelling doesn't represent anything more sinister such as disease recurrence for example in patients with treated gynaecological malignancy. Methods: ii Using the guideline from the British Society of Nuclear medicine and the evidence in the current literature our institution adopts the following imaging protocol; Injection site: A single subcutaneous injection between the web spaces of both feet or hands. The injection volume is below 0.25mls as the dermal space is so small. Injection: Technetium-99m Nanocolloid, ARSAC reference level 20MBq per limb. Page 6 of 15

7 Image Acquisition: Both limbs imaged simultaneously using a whole body sweep at 10cm per minute from injection site to upper abdomen including the liver. Early views of the liver are useful to exclude an accidental intravenous injection, on late views liver activity can confirm completion of the lymphatic circuit. Imaging of the injection site is important even on delayed images to observe for dermal backflow which can appear late. Image Timing: Immediately after injection, at 30 minutes, 1 hour and 3 hours. Cobalt markers can be used to highlight anatomical landmarks. Interpretation: Our institution uses both qualitative and quantitative data analysis. Qualitative Analysis: A normal scan would demonstrate prompt uptake by the lymphatic vessels with the visualisation of discrete lymph nodes in the inguinal chains by 1 hour, para-aortic chains by 2 hours and the liver by 3 hours signifying completion of the study (Fig 2). Abnormal scans can demonstrate a range of different findings; 1. Absent or reduced uptake in the lymphatic vessels in comparison to the other side (Fig 3) with reduced uptake/visualisation of lymph nodes and delayed transit of tracer up the lymphatic vessels on the affected side. 2. Collateral flow into the deep lymphatics manifesting as visualisation of the popliteal lymph nodes (Fig 4), and collateral flow with the superficial skin lymphatics which can cause dermal back flow (Fig 5) and manifest as the 'stocking sign' (Fig 6). 3. The presence of lymphocoeles and lymphangiectasia. Quantitative analysis Our institution also uses a quanititative anlaysis alongside interpretation of the images. Activity values from our own studies were correlated with the clinical outcome in a collection of patients and using this with values in the current literature a range of normal uptake values at each time interval have been established. Page 7 of 15

8 Each patient has their own uptake values measured at 30 minutes, 1 hour and 3 hours and has them plotted on a reference graph. If the patients line lies below the normal reference line this can support a diagnosis of lymphoedema (Figures 2-6). These findings can help to support a positive scan however should not be interpreted alone. Page 8 of 15

9 Images for this section: Fig. 2: Normal study demonstrating rapid transit of tracer along the lymphatics with symmetrical inguinal lymph nodes. Sheffield school of radiology - Sheffield/UK Page 9 of 15

10 Fig. 3: Swift tracer uptake in the right lymphatic vessels that decreases overtime with clear activity in the right inguinal nodes. No uptake demonstrated in the left lymphatic chain and reduced activity in the left inguinal lymph nodes in keeping with left sided lymphoedema. Sheffield school of radiology - Sheffield/UK Page 10 of 15

11 Fig. 4: Demonstration of the popliteal lymph nodes can be a secondary sign of lymphoedema signifying collateral connection with the deep lymphatic chains. Sheffield school of radiology - Sheffield/UK Page 11 of 15

12 Fig. 5: Dermal backflow demonstrated in the left calf. Sheffield school of radiology - Sheffield/UK Page 12 of 15

13 Fig. 6: 'Stocking sign' in the right leg representing collateral flow with the skin lymphatic system. Sheffield school of radiology - Sheffield/UK Page 13 of 15

14 Conclusion The impact of a positive result: A diagnosis of primary lymphoedema can be clinically challenging and it is important to establish a diagnosis as these patients are often younger and require higher compression to control their symptoms. A confirmed diagnosis can also help them cope with the psychological and social implications of the condition. In ambiguous cases it is important to establish the diagnosis to exclude a different, treatable cause of the limb swelling for example cellulitis, and also to ensure that new onset leg swelling doesn't represent anything more sinister such as disease recurrence for example in patients with treated gynaecological malignancy. The qualitative information from the study can also help focus the treatment and use more targeted compression therapy to reduce the symptoms of limb swelling and distortion, repeated studies can also be utilised to monitor the patients response to treatment. Page 14 of 15

15 References [i] on page File:Blausen_0623_LymphaticSystem_Female.png [ii] on page DSECTION=causes [iii] on page Lymphoscintigraphy_with_referencesCF.pdf Page 15 of 15