Ly m p hoscln tig ra p hic Stud ies in Patients W it h Ly mp hedema To tht Editor: I read with dismay Dr. Howarth's anicle entitled "Increased Lymphoscintigraphic How Pattern in the Lower Extremity Under Evaluation for Lymphedema," which was published in the May 1997 issue of the Mayo Clinic Proceedings (pages 423 to 429). Mindfulof thedevastating effectsof minortrauma (such as injections) the limbs of patients with lymphedema-e-effects that can often be irreversibly disfiguring-I searched in vain through the article for some evidence that the procedure (lymphoscintigraphy)led to any alteration in thetherapeutic management of any of the 51 patients in the series. The advancement of knowledge is salutary. but its value must be weighedagainst the risk of permanent disfigurement of patients.
'0
Sheldon S. Schoen. M.D. Livingston. New Jersey
phatic vessel that is then cannulated. The radioconrrasr material thai is then introduced under pressure is a highly viscous, iodine containing medium that has been associated with lymphangitis. sclerosis. and even embolic phen omena," The distinction between these two tests is important. Because of its safety and simplicity, lymphoscintigraphy is frequently used to investigate swelling of the extremities. This testcan help distinguish lymphedemafrom swelling due to other causes and has recenl1y been used to predict lymphatic malignant spread oft umors.' Its value lies in its ability 10 demonstrate lymphatic physiologic and pathophysiologic features. Despite theassociated potential adverseeffects, lymphangiography can also be useful in delineating lymphat ic structures before surgical intervention in patients with congenital abnormal ities," Ob viously, the potential benefits of any technique must outweigh the associated risks. Thus,lymphoscinligraphy remains thesafest. best tolerated, and most "physiologic" means of assessing lymphatic function. Douglas M. Howarth. M.D. John Hunter Hospital Newcastle, New South Wales, Australia
In response: Dr. Schoen makes an important point regarding
invasive testing in patients with lymphedema-that minor trauma in such patients can exacerbate the conditio n. Lymphoscintigraphy. however, does not produce adverse reactions of this type andhas not been associated withexacerbation of lymphedema orlocal inflam ma tion since the technique was refined 10 include use of the radioisotope technetium 99m <-I'c). ""'Tc is a readily available isotopewitha gamma emissionof 140keY anda half-life of 6 hours. With a standard dose of 20 to 40 MBq. radiation dosimetry 10 the periphery is about 0.15 '0 0.30 Gy.' The lest involves a shallow subcutaneous injection of a total volume of 0. 1 mL of 99In"fc bound to minute panicles of sulfur colloid that have a mean size of 60 nm .! Panicles of this size travel rapidly and freely through the lymphatic vessels without interfering with lymp hatic function. When lymphoscintigraphy was pioneered in the early 19505, various isotopes with less favorable radiation dosimetry were used. These isotopes included gold Au 198. which is no longer advocated because of reponed local necrosis at injeclion sites.'
ln contrast to ""'Tc-sulfur colloid lymphoscintigraphy, the radiographic technique of lymphangiography is a truly invasive test. Often, a small incision is necessary to expose a peripheral lym-
REFEREN CES I. O'Connor MK, editor. The Mayo Clinic Manual of Nuclear Medicine. New York: Churchill Livingstone; 1996 2. Hung Je. Wiseman GA. Wahner HW. Mullan BP. Taggart TR. Dunn WL. Filtered lechnedum-99m-sulfur colloid evaluated for Iymphoscintigraphy. J Nuel Med 1995;36:1895-1901 3. Oshome MP. Meijer WS. Yeh SO. DeCosse JJ. Lymphoscintigraphy in the staging of solid tumors. Surg Gynecol Obstet 1983;156:384-39 1 4. Gloviczki P, Wahner HW. Clinical diagnosis and evaluation of lymphedema. In: Rutberford RB. editor. Vascular Surgery. Vol 2. 4th ed . Philadelphia: Saunders; 1995 5. Uren RF. Howman-Giles RB. Sha w HM. Thompson JF. McCarthy WHo Lymphoscinligraphy in high-risk melanoma of the trunk: predicting draining node groups. defining lymphatic channels and locating the sentinel node. J Nuel Med 1993;34:1435-1440 6. Gloviczki P, Calcagno D. Schirger A. Pairolero PC. Cherry KJ. Hallett JW, et al. Noninvasive evaluation of the swollen extremity: experiences with 190 Iymphoscintigraphic examinations. J Vasc Surg 1989;9:683-689
The Editor welcome s lett ers and co mments . parti cularly pertaining to recently pu bli shed artic les in the Mayo Clinic Proceedings. A letter should be no lo nger than 500 words. contai n no more than 5 referen ce s, and be in a double-spaced. typewritten form at. The letter should be signed. II is ass umed tha t appropriate letters may be published. at the discretion of the Ed itor , unless the writer indicates ot herwise. The Editor reserves the rig ht to edi t lett ers in acco rda nce with the Mayo Clinic Proceedings style and to abridge them if necessary .
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.