Lymphoscintigraphy is not a fresh ...

Lymphoscintigraphy is not a fresh technique, but its use in the OR is revolutionizing cancer surgery It is a performance that poses technical challenges and requires an interdisciplinary approach. Sentinel lymph node biopsy commonly is used for patients diagnosed with early stage cutaneous melanoma. Physicians are facing a slip back in melanoma cases; it is estimated that more than 40000 modern cases will have been diagnosed in 1997(1) There are other applications for sentinel lymph node biopsy, on the other hand this article focuses on the efficacy of this operation for use in patients with melanoma.

CANCER AND THE LYMPHATIC SYSTEM

The pathology of cancer is difficult to generalize, further with many tumors, the mechanism of invasion, or local spread, is speculation to be the same. Tumor pullulation invariably leads to the invasion of the lymphatic a whole Tumor cells trespass the delicate lymphatic channels, embolize, and are carried toward a lymph node, where they become trapped.(2)

Lymph nodes are generally establish in groups known as chains or basins. Drainage of dead body tissues via the lymphatics progresse proximally from channels to nodes (in basin or chains), and then rouses toward the central ducts located in the thoracic cavity. single in kind of the primary functions of the lymphatic order is to cleanse surrounding material part tissues. When foreign particles are filtered disclosed of lymph fluid by the lymph nodes, leukocyte rejoin to engulf and destroy the invaders, swelling the lymph node as the inflammatory proces progresse This is with what intent lymph nodes become enlarged when the visible form [i]or[/i] frame is fighting off antigens.

This mechanism, however, does not pretend to prevail when the lymph node is "seeded" with tumor small rooms Cancer cells are aggressive and are capable of prosperous multiplication in sites very different than their originating tissue. When the tumor tonnage becomes high enough, cancer lonely dwellings spill out of the first lymph node and continue to spread along the afferent lymphatic channels.(3) The local spread of the primary tumor then progresse as other lymph nodes are seeded

THE SENTINEL LYMPH NODE

Tumor spread to regional lymph nodes initially advances from the primary tumor site to a single lymph node. This important node has been designated the "sentinel" lymph node. by the agency of virtue of its tumor status in succession biopsy, this node is predictive of the disease progres in cases of cutaneous melanoma. When the sentinel lymph node is tumor exempt it can be assumed that the cancer has not spread to other lymph nodes in the lymphatic basin or chain.(4) reciprocally if tumor cells are not away in the sentinel lymph node, then tumor site. The isotope is taken up by the agency of the lymphatics and is carried to the sentinel lymph node. A high-resolution gamma camera equipped with a large field of view is used to map the isotope's path (Figure 1)

[Figure 1 ILLUSTRATION OMITTED]

The images generated according to an isotope are created as the simple body decays and are akin to stippling paper with a pen; the more times the compose is touched to the paper in a single area, the more intense the ink taint Likewise, the higher the concentration of radioactivity (ie, emitted gamma rays), the brighter the blot The image is, in fact, a collection of white stains on a black background. A lymph roll on study is performed with dynamic (ie, real time) imaging in subordination to the observation of a certified nuclear medicine technologist (CNMT) The design of this study is to note any early migration of the [sup99m]Tc(6) When the dynamic investigation is completed, static images are produc at regular intervals until the sentinel lymph node is seen (Figures 2 and 3) All images of the isotope are digitally produc and stored. After the sentinel node is confirmed in couple views (eg, anterior-posterior, lateral planes), the surgical biopsy can proceed

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GAMMA-DETECTING INSTRUMENT

The sentinel lymph node biopsy come abouts in the OR and is at the disposal of on the localizing guidance of a gamma ray-detecting instrument equipped with a cadmium zinc telluride crystal probe (Figure 4) The gamma-detecting instrument is compact and measures 29 cmx 38 cm and weighs just more than 6 kg It has a hand-held probe that is placed in a sterile drape for probing within the surgical incision.

[Figure 4 ILLUSTRATION OMITTED]

The gamma-detecting instrument is a sophisticated Geiger reckoner The Geiger counter (also known as the Geiger-Muller or G-M counter) measures the activity, in deems per second, of gamma-emitting substances. principally people are familiar with the crescendo of clicks heard from a Geiger reckoner as it senses a radioactive substance. The gamma-detecting instrument used in the OR also features an audible signal that assists the surgeon in localizing the radioactive sentinel lymph node.

Another feature of the instrument is a digital display to visually confirm the gamma ray enumerates The hand-held probe, which describes a significant percentage of the instrument's require to be paid [i]or[/i] undergone contains a very delicate sensing crystal that is as brittle as chalk. The probe, therefore, should be handled carefully, and precautions should be taken to avoid dropping it.