Learning Solutions from
GE Medical Systems
Program Supplement
NM: Special Imaging Techniques
1173
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  1. 1. Learning Solutions from GE Medical Systems Program Supplement NM: Special Imaging Techniques 1173 TiP-TV TM GE Training in Partnership Television © 2002 General Electric Company. All rights reserved.
  2. 2. 2 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 TABLE OF CONTENTS SECTION PAGE PREFACE TABLE OF CONTENTS ......................................................................................................... 2 PRESENTER BIOGRAPHIES ................................................................................................ 3 SPECIAL CONTRIBUTORS ................................................................................................... 4 PROGRAM OBJECTIVES, TARGET AUDIENCE, AND PRODUCTIVITY STATEMENT .............. 5 PROGRAM OUTLINE ............................................................................................................ 6 DEEP VEIN THROMBOSIS.................................................................................................................... 7 GASTROINTESTINAL (GI) BLEED IMAGING...................................................................................... 15 SALIVARY GLAND IMAGING .............................................................................................................. 21 APPENDIX A: DVT IMAGING WITH ACUTECT .................................................................................. 24 APPENDIX B: TESTICULAR IMAGING ............................................................................................... 26 APPENDIX C: DACRYOCYSTOGRAPHY .......................................................................................... 27
  3. 3. 3 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 PRESENTER BIOGRAPHIES Rosemary Messner, BS, CNMT - GE Medical Systems Nuclear Applications Specialist Rosemary holds a Bachelor of Science degree in Computer Science from Carroll College in Waukesha, Wisconsin. In addition, she is a certified Nuclear Medicine Technologist with an Associate of Science degree in Nuclear Medicine Technology from the University of Cincinnati. She worked as a staff technologist and radiation safety officer in Cleveland, Ohio for 15 years. Rosemary joined GE Medical Systems in February, 1993. She provided clinical assistance to customers on the GE TiP Applications OnLine Service Answerline for three years. As an Operator Information Development specialist, she developed TiP Tutorials for the Nuclear GENIE Processing and Review workstation. She has also developed and presented various customer training programs such as Level 1 Starcam training at the GE Education Center and technologist training seminars. Rosemary is currently a Nuclear Applications Specialist for the Central Region based in Lexington, Kentucky. She is responsible for training nuclear medicine technologists and physicians on GE products. Jean A. Schmitz, BS, CNMT - GE Medical Systems Nuclear and Mammography TiP-TV Program Coordinator Jean holds a Bachelor of Science degree in Nuclear Medicine Technology with a Chemistry minor from the University of Wisconsin - LaCrosse. She worked as a staff nuclear medicine technologist and clinical instructor at St. Joseph's Hospital/Marshfield Clinic in Marshfield, Wisconsin for five years. Jean joined GE Medical Systems in 1988 and was responsible for training applications personnel world-wide, and assisted in product development and validation. Jean was a member of the team that developed and implemented the TiP, Training in Partnership, education program platform. As the Nuclear and Mammography TiP-TV Program Coordinator, Jean is responsible for coordinating, developing and presenting training programs to nuclear medicine and mammography personnel via the TiP-TV satellite network.
  4. 4. 4 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 SPECIAL CONTRIBUTORS Darlene Fink-Bennett, MD Co-Chief of the Department of Nuclear Medicine William Beaumont Hospital Royal Oak, MI N. David Greyson, MD, FRCPC Associate Professor of Radiology and Nuclear Medicine St. Michael’s Hospital Toronto, Ontario, Canada Bruce R. Line, MD Professor of Radiology and Attending Physician in Nuclear Medicine Albany Medical College Albany, NY Raymond Taillefer, MD, FRCPC, A.B.N.M. Professor of Nuclear Medicine University of Montreal Montreal, Quebec, Canada Jack Ziffer, PhD, MD, FACC Medical Director of Nuclear Medicine Baptist Hospital Miami, FL
  5. 5. 5 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 PROGRAM OBJECTIVES, TARGET AUDIENCE, AND PRODUCTIVITY STATEMENT Program Objectives By the end of this program, the viewer should be able to: • Discuss the process for detecting deep vein thrombosis. • Explain the techniques used for gastrointestinal imaging. • Discuss the techniques used for salivary gland, testicular and dacryocystography imaging. Target Audience Course objectives for this program specifically target all nuclear medicine personnel. While not limited to this audience group, the technical content will be most effective when applied to people with this training. NOTE: Viewers who apply for continuing education (CE) credit and meet the application requirements are eligible for credit, regardless of their audience status. Productivity Statement This program was developed to enhance your professional and educational level, and increase your productivity and skills.
  6. 6. 6 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 PROGRAM OUTLINE NM: Special Imaging Techniques I. Deep Vein Thrombosis A. Vascular Anatomy B. Non-Nuclear Imaging Modalities 1. Contrast Venography 2. Duplex Ultrasonography 3. Magnetic Resonance Angiography 4. Computed Tomography (CT) 5. Impedance Plethysmography (IPG) C. Nuclear Techniques D. Thrombus-Binding Peptides II. Gastrointestinal Imaging A. Gastrointestinal (GI) Bleed Imaging B. Meckel's Diverticulum III. Salivary Gland Imaging A. Salivary Gland Case Review
  7. 7. 7 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 DEEP VEIN THROMBOSIS • About 5 million cases of deep vein thrombosis (DVT) are reported each year in the United States – Approximately 10% of these patients are diagnosed with pulmonary embolus, which is a potentially fatal complication of DVT • As high as 52% of patients autopsied in the United States were found to have some evidence of pulmonary embolism – This was believed to have contributed to the patient’s death in 14% of these cases • With DVT and pulmonary embolism being a major cause of morbidity and mortality throughout the world, it’s important to have some method of quickly and accurately diagnosing acute venous thrombosis, before serious complications are realized • There are many common clinical symptoms that suggest acute DVT: – Edema – Swelling – Warmth – Redness – Pain • Certain conditions or situations may increase the risk of acute DVT: – Recent pelvic operation or hip or knee replacement – Recent trauma – History of cancer – Estrogen therapy – Recent travel – Stasis – Congestive heart failure – Obesity – Prior history of DVT – Family history of thrombosis
  8. 8. 8 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 VASCULAR ANATOMY Graphic courtesy of Diatide, Inc. and Nycomed Amersham • The greater saphenous vein extends the length of the each leg along the medial border – This is a superficial vein – A thrombus in this vein is not considered to be a deep vein thrombosis • The femoral and deep femoral veins in the thigh arise from the external iliac vein – The femoral and deep femoral veins are both positioned anteriorly • The greater saphenous, femoral, and deep femoral veins all branch off at about the same point • Near the knee the femoral vein moves posteriorly and becomes the popliteal vein – Any compression of the knee, such as a pillow or angle sponge, could easily cause temporary obstruction of the this vein • The anterior tibial veins, posterior tibial veins, and peroneal veins are all paired veins and arise from the popliteal vein – The anterior tibial vein runs along the anterolateral edge of the tibia – The posterior tibial vein lies along the posteromedial edge of the tibia – The peroneal veins also lie posteriorly and are lateral to the posterior tibial veins 1. Greater saphenous vein 2. Femoral vein 3. Deep femoral vein 4. Popliteal vein 5. Anterior tibial veins (paired) 6. Posterior tibial veins (paired) 7. Peroneal veins (paired) Deep Veins: #2, 3, 4, 5, 6, 7 Superficial Veins: #1 ANTERIOR POSTERIOR 1 2 3 4 5 6 7
  9. 9. 9 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • There are a variety of procedures that rely primarily on detecting the effects of the thrombosis, such as altered venous return pathways resulting from partial or total venous occlusion, rather than the process – Process: activated platelets causing aggregation and thrombus formation – Effect: vascular obstruction or filling defect Graphic courtesy of Diatide, Inc. and Nycomed Amersham NON-NUCLEAR IMAGING MODALITIES • There are two primary non-nuclear modalities used to detect DVT – Contrast venography – Duplex ultrasonography Contrast Venography • Contrast venography has been considered the “gold standard” for the diagnosis of DVT • This procedure involves the injection of a contrast medium into a dorsal foot vein and allows the entire lower extremity to be imaged with a high level of detail • Limitations of contrast venography – An invasive procedure that can be very painful – Technically demanding – Frequently fails to distinguish between acute and old thrombi – In 20% to 25% of patients, procedure cannot be performed or there is inadequate visualization of the deep veins – Patient condition interferes with exam ! Obesity ! Severe edema ! Cellulitis of a limb ! Limited mobility ! Leg cast
  10. 10. 10 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 – Incorrect diagnosis can result from an inadequate venogram ! Large thrombus not detected due to appearance of normal blood flow ! Streaming effect of the contrast makes it appear that a thrombus exists when it does not – Contraindicated in patients with the following conditions ! Contrast media allergy ! Congestive heart failure ! Renal insufficiency Duplex Ultrasonography • At many institutions, duplex ultrasonography is the first imaging procedure used to diagnose acute DVT • Combines real-time or continuous wave compression sonography with Doppler evaluation – Deep veins are visualized directly with real-time ultrasonography or with continuous wave compression sonography – Doppler technology identifies, measures, and displays the blood flow within the vessels – Non-invasive • Limitations of ultrasonography – Fresh thrombus may not be detected due to its lack of echogenicity – Cannot differentiate acute versus chronic thrombus – Chronic changes to the blood vessels from a previous episode of DVT may be misdiagnosed as acute DVT – Identification of DVT in the calf is very limited – Results are highly operator dependent – False positives can occur from compression of the transducer on the underlying vein – Anatomical variants, such as collateral vessels, may cause false negatives – Patient condition can interfere with the study ! Obesity ! Leg casts ! Mobility Magnetic Resonance Angiography • Magnetic resonance (MR) angiography provides the potential for imaging the important venous channels, even the proximal upper limb veins • Technologies for peripheral vascular imaging with MR are still evolving – Contrast agents – Coils Computed Tomography (CT) • Computed tomography can detect DVT in the abdomen, pelvis, and limbs • Superior to contrast venography for proximal disease • Useful in complicated cases involving the abdomen and pelvis
  11. 11. 11 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 Impedance Plethysmography (IPG) • Measures the capacity of the venous system to fill and empty by measuring volume changes in the leg – By inflating and deflating a pneumatic thigh cuff, changes in electrical resistance (impedence) are measured – These changes are decreased in patients with venous obstruction • Limitations of IPG – Does not identify the specific cause of decreased venous flow – Can not distinguish between acute and chronic DVT – May not detect small occlusions – Presence of collateral vessels may give false negative – Sensitivity of the procedure varies widely, depending upon the patient population NUCLEAR TECHNIQUES • Two methods detect the effects of venous obstruction – Radionuclide venogram using 99m Tc macroaggregated albumin (MAA) – Radionuclide venogram using 99mTc-labeled red blood cells (RBC) • Radionuclide venogram using Tc-99m macroaggregated albumin (99m Tc MAA) – 1.5 to 2 mCi (55 to 74 MBq) of tracer is injected into the dorsal pedal vein – Dynamic images are obtained to evaluate the blood flow through the vessels – 80% to 90% accuracy for detecting DVT in the thigh – Allows a perfusion lung scan to be performed without an additional injection - – It’s limitations are similar to contrast venography • Radionuclide venogram using 99m Tc -labeled red blood cells (RBC) – This technique relies on identifying changes in the normal venous anatomy by comparing one leg to the other – Values reported for this procedure’s sensitivity and specificity vary significantly ! Sensitivity: 68% to >90% ! Specificity: 88% to >90% – Limitations ! Unable to determine the cause or the likely age of the venous obstruction ! Must follow very strict guidelines for the procedure ! Poor labeling, positioning, and imaging can result in non-diagnostic or misleading results • Positioning of the limbs is critical to the results – The limbs must be in an exact and symmetrical position – External compression by pillows, elastic bandages, or stockings can cause false-positive results • Instead of relying on the effects of venous obstruction, other nuclear medicine techniques have attempted to detect the formation of acute thrombus
  12. 12. 12 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • Iodine-125 labeled fibrinogen uptake tests – This was the earliest agent used for detecting active clot formation – A hand held probe was used to count about 12 to 20 locations on each leg and record the counts as a percentage of the precordial (heart) activity – This was repeated daily for 2 to 6 days, depending upon the results – While this technique was a bit primitive and no imaging was performed, this was a relatively sensitive test for detecting DVT – Iodine-125 fibrinogen is no longer produced commercially in the United States • In the late 1970s, Indium-111 labeled platelets were investigated as an agent for the detection for the development of DVT – This agent had good sensitivity (69% at 4 hours, 100% at 24 hours) and specificity (92% at 4 hours, 89% at 24 hours) – Limitations ! 15% to 30% of patients, especially those who had venous stasis or low-grade thrombosis, required 18 to 24-hour delayed imaging in order to obtain diagnostic results ! Anticoagulation therapy (Heparin or warfarin therapy) could interfere with the test, possibly causing false-negative results ! The procedure for labeling and reinjecting the platelets can take 1.5 to 2 hours ! False-positive results may be seen due to " Trauma to the veins " Venipuncture " Hematomas " Hemangiomas " Varicose veins " Inflammation ! Cost and availability of 111 In-oxine • Many new radiopharmaceuticals have been, or are being, evaluated for the detection of acute DVT – T2G1s antifibrin monoclonal antibody – Antiplatelet monoclonal antibodies – Monoclonal antibody fragments – Thrombus-binding peptides • Antibody fragments without the Fc portion are preferred – More rapid blood clearance – The lower molecular weight may permit greater penetration into the thrombus – Less likely to cause immune reactions • One study showed that fragments labeled with 99m Tc cleared faster than those labeled with 111 In • Anticoagulants interfere with the labeling of most antifibrin and antiplatelet antibodies
  13. 13. 13 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • Antibodies to tissue antiplasminogen activator (t-PA) have also been used for DVT imaging – This antibody has a rapid blood clearance half-time and background can be significantly decreased by injecting the t-PA antigen in subtherapeutic doses – Another possible advantage is that uptake of this agent (anti-t-PA) by the thrombus may be unaffected by circulating anticoagulants (heparin, etc.) THROMBUS-BINDING PEPTIDES 99m Tc-labeled Apcitide (AcuTect) • Approved by the Food and Drug Administration in 1998 – Diatide, Inc and Nycomed Amersham • Apcitide is indicated for scintigraphic imaging of acute venous thrombosis in the lower extremities of patients who have signs and symptoms of acute venous thrombosis – Appears to detect acute and not chronic venous thrombosis (not confirmed clinically) • Binds preferentially to the glycoprotein (GP) IIb/IIIa receptors found on activated platelets Graphic courtesy of Diatide, Inc. and Nycomed Amersham • Based on clinical trials, anticoagulation therapy had no significant effect on the sensitivity and specificity of the AcuTect examination
  14. 14. 14 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • Acquisition technique plays a critical role in the proper interpretation of AcuTect imaging – Have patient drink plenty of fluids and void frequently to decrease background activity – Void before imaging to reduce bladder activity – Make sure foley catheter tubing is out of the field of view during imaging – Make sure there is no external compression on the deep veins, especially in the popliteal region ! Do not place a pillow under the knees – Position both legs straight, and in the exact same position, for accurate comparison between both legs • Case review of AcuTect images – Case 1: Normal – Case 2: Left Calf DVT 9m Tc labeled DMP-444 • Developed by the DuPont Pharmaceuticals Company • Binds to the glycoprotein (GP) IIb/IIIa receptors found on activated platelets
  15. 15. 15 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 GASTROINTESTINAL IMAGING GASTROINTESTINAL (GI) BLEED IMAGING • Indications – Detect and localize the site of active gastrointestinal bleeding – Guide for surgical therapy without the need for angiography – Help patient management by determining the need for aggressive therapy and transfusions • Common causes of upper GI bleeding in adults – Peptic ulcer disease – Gastritis – Esophagitis – Varices • Causes of lower GI bleeding – Massive bleeding ! Diverticular disease ! Polypectomy ! Angiodysplasia – Submassive bleeding ! Tumors ! Inflammatory or ischemic bowel disease • Massive bleeding is defined as blood loss that exceeds 30 ml/hr – It is most often due to diverticular disease – 80% to 90% of these bleeds stop spontaneously, but there is a 25% recurrence rate – If the cause is angiodysplasia, there is an 85% recurrence rate • Imaging agents – The primary imaging agent used for GI bleed studies is an intravenous injection of 20 to 30 mCi (740 -1110 MBq) of 99m Tc labeled red blood cells (RBC) – Some sites use a 10 to 15 mCi (370 - 555 MBq) injection of 99mTc sulfur colloid (SC) • Both agents provide similar information and appear to be up to 10 times more sensitive in the detection of lower GI bleeding than angiography, without being invasive • Contrast angiography has the advantage of being able to identify possible causes of the bleed even though the patient may not be actively bleeding, i.e. vascular tufts of angiodysplasia – Angiography also allows the possibility of intra-arterial vasopressin therapy • Angiography is capable of detecting bleeding rates of around 1.0 ml/minute – If there is intermittent bleeding, or a slower bleed rate, you might get a false negative exam • Studies with 99mTc sulfur colloid have detected bleeding rates as low as 0.05 to 0.1 ml/minute • Technetium labeled red blood cells have a minimal detectable bleeding rate of 0.1 to 0.35 ml/minute • With both agents, the severity of the bleed correlates with the amount of tracer seen in the lumen
  16. 16. 16 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • In most cases, 99mTc labeled red blood cells is the agent of choice – The major advantage of labeled red blood cells is that they remain in the intravascular space for up to 48 hours – Allows repeat imaging, and makes it much more likely to identify a bleeding site since GI bleeds are typically intermittent • The quality of the labeling technique can significantly affect the quality of the images • The in-vivo method is the simplest technique – Labeling efficiency of only 85%, so there may be interference from free technetium in the intestinal tract and kidneys – IV injection of stannous ion (pyrophosphate) – 20 minute waiting period – IV injection of 20 mCi (740 MBq) 99mTc pertechnetate • The modified in-vivo method was initially the most commonly used technique – The labeling efficiency is around 92% to 95% – Easy method and provides good image quality, assuming the entire study is performed with good technique – Low possibility of infectious contamination – IV injection of stannous ion (pyrophosphate) – 20 minute waiting period – Draw patient’s blood into an anticoagulated syringe containing 20 mCi (740 MBq) of 99mTc pertechnetate – Gently mix contents for 10 minutes – Inject labeled blood back into patient • The in-vitro method is the technique recommended by the Society of Nuclear Medicine – Labeling efficiency of greater than 97% and has a very stable tag – Imaging can be performed at 24 hours without significant interference from free pertechnetate – Good blood handling and tagging techniques are critical with this method, especially if you are working on multiple preparations ! It is possible to mix up the samples and inject a patient with the wrong preparation, exposing them to an infectious disease ! Matching patient and sample ID tags are useful in avoiding mixing up multiple patient samples – Easiest to label cells using a kit such as UltraTag – Non-kit labeling should take place in a laminar flow hood – Costs more than other techniques • The sulfur colloid (SC) method is preferred in patients with collateral abdominal vessels that can obscure bleeding sites in the red blood cell exam – Sulfur colloid particles are rapidly cleared from the blood by the liver and spleen – It is not absorbed by the bowel so there is no interference with background activity – The activity in the liver and spleen may obscure upper abdomen bleed sites • In order for a bleed site to be detected using SC, active bleeding needs to take place during the time the sulfur colloid is in the intravascular space, which is about 15 to 20 minutes – If the patient has a significant intermittent hemorrhage, you may get a false negative result
  17. 17. 17 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • One way to minimize this effect is to divide a double dose of 99mTc SC into four separate doses – Administer repeated injections over a 30 minute or longer time period – This increases the time that the agent is circulating and thus available for bleed detection – This may increase the sensitivity of the exam • General guidelines for imaging – Use a large field of view detector fitted with a low energy, general purpose or high-resolution collimator – If the exam is performed as a portable, use a diverging collimator – There is no special patient preparation required – Make sure your patient did not have any exams which may conflict with the GI bleed exam - such as an X-ray procedure which used contrast media – The acquisition technique will vary depending upon which imaging agent used • Acquisition guidelines for 99m Tc RBC – Patient supine on the imaging table – Position the detector over the anterior abdomen and pelvic areas – Inject patient with the labeled RBCs – Imaging should be started immediately post injection – 128 x 128 acquisition matrix – An abdominal flow study is performed for 1 minute using 1 to 5 seconds/frame – This is followed by a series of dynamic images acquired for 10 to 60 seconds/frame over a 60 to 90 minute period ! If possible, these dynamic images should be split into several sets of images of about 10 to 15 minutes each ! This enables your physician to review images while the next set is being acquired – Once a bleeding site has been identified and localized sufficiently, the exam can be terminated without continuing for the entire 90 minutes – Non-dynamic images can be obtained if computer acquisition is not possible ! Sequential static images every 5 minutes for 60 to 90 minutes ! 1 million counts per image • Delayed imaging may be required in order to make the diagnosis – These are typically performed from 2 to 6 hours and/or at 18 to 24 hours post injection – Acquire either as dynamic or static images – Static images typically use a 128 matrix and obtain at least 500K counts • Delayed images are useful in showing subsequent bleeding and the severity of the bleed – The actual bleeding site may not be correctly identified – If a bleed has been detected and the patient is actively bleeding, performing a dynamic study at the time of the delayed imaging may give additional localization information • Additional views in different projections may help to further localize the bleeding site – Lateral views are useful in detecting rectal bleeds – Anterior oblique and posterior views are helpful in differentiating whether the bleed is anterior or posterior
  18. 18. 18 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • Use regions of interest drawn over the bleed to estimate blood loss – Must normalize counts from imaging to counts injected in syringe for accurate estimates • If extravasated blood does not move, you can use several additional methods to help localize bleed – Review of previous barium studies – Oral 99mTc sulfur colloid to outline the upper GI and small bowel anatomy – 99m Tc sulfur colloid enema to outline the colon • Acquisition guidelines for 99mTc sulfur colloid method – Pay careful attention to the imaging technique – Have the patient lay in a supine position and place the camera over the anterior abdominal and pelvic regions – Inject the patient with the 99mTc -SC – Place a shield over the liver and spleen activity if desired – Dynamic imaging ! 64 x 64 matrix ! 1 image every 15 to 60 seconds for 10 to 15 minutes – Static imaging ! 128 x 128 matrix ! 500K counts ! Every 1 to 2 minutes for 15 minutes – You may want to acquire anterior oblique images to see areas obscured by liver and spleen activity – If you don’t see any bleed site, it may be helpful to extend the imaging for another 15 minutes to allow activity hidden by the liver or spleen to move distally to an area where it can be seen – If the initial study is negative, you can repeat the exam as requested by your physician • When reviewing the images, it is important to be able to identify normal landmarks as well as abnormal activity • Sometimes, conditions exist which may interfere with the accuracy of the GI bleed results
  19. 19. 19 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 MECKEL'S DIVERTICULUM • Meckel’s diverticulum is a common cause of gastrointestinal bleeding in children – Sac or diverticulum on the small intestine which is an acute remnant of the omphalamessenteric duct – Meckel’s diverticula often contain gastric mucosa • Indications – Determine location of Meckel’s diverticulum – Gastrointestinal bleeding in children and young adults • Radiopharmaceutical – 99mTc pertechnetate is the agent of choice because it is picked up by ectopic gastric mucosa • Dosage – Intravenous injection – Adults: 8 to 12 mCi (296 - 444 MBq) – Children: 200 to 300 µCi/kg (7.4 - 11.1 MBq/kg) ! Use a minimum of 2 mCi (74 MBq) in pediatric patients • Collimator: Low Energy General Purpose, parallel hole • Patient preparation – None – Make sure patient did not have recent upper GI series or barium enema exams • Acquisition parameters and technique – Position patient supine on the table, with camera placed over the anterior abdomen ! May also use left lateral decubitus position to decrease small bowel activity arising from stomach – Large field of view detector – 128 x 128 matrix – Inject the patient – Optionally acquire flow study with 1 to 5 seconds/frame images for 1 minute – Acquire dynamic anterior mid-abdominal images at 30 to 60 seconds/frame for 30 to 60 minutes – Can also acquire a series of static anterior midabdominal images every 5 minutes for 30 to 60 minutes ! 500K counts – Additional anterior oblique, lateral, and/or posterior views are recommended to help localize site ! Stopping the dynamic acquisition when the bleed is identified to perform additional views will help distinguish bleed from kidneys, ureter, or bladder ! Post-void images are useful to detect activity obscured by bladder • Recently suggested for actively bleeding patients with suspected Meckel’s diverticulum – First perform GI bleeding exam to detect bleeding site rather than the ectopic mucosa – If using SC, a negative bleeding exam can be followed immediately by a Meckel’s diverticulum exam – If using Tc-99m labeled red blood cell, cold stannous pyrophosphate will cause pertechnetate to label red blood cells instead of localizing in Meckel’s – Effect may last for days after administration
  20. 20. 20 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • Results – Typical positive exam shows a focal area of increased activity in the right lower quadrant, which on a lateral view, is seen to be anterior and unrelated to ureteral activity – Normally see defect within first 30 minutes but may take up to an hour, depending on the amount of gastric mucosa present – Overall specificity and sensitivity for Meckel’s imaging is about 90% • Several pharmacologic interventions have been discussed which may increase the sensitivity of Meckel’s imaging – Methods have varying degrees of success – Cimetidine: blocks release of pertechnetate from cells increasing gastric and ectopic mucosa uptake – Pentagastrin: enhances mucosal uptake of pertechnetate ! Also stimulates pertechnetate secretion and GI motility; may reduce ectopic site activity ! Can use nasogastric suction to remove intragastric activity – Glucagon: decreases small bowel (diverticular) motility and peristalsis • False positive results – Intussusception (possibly related to associated hyperemia) – Urinary tract activity (often secondary to obstruction) – Various bowel lesions – Inflammatory bowel disease – Rarely: intestinal duplication cysts containing gastric mucosa • False negative results – Malrotation of the ileum – Small amounts of ectopic mucosa – Localized bowel irritability resulting in rapid clearance of pertechnetate from the area
  21. 21. 21 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 SALIVARY GLAND IMAGING • Salivary gland imaging, also known as nuclear sialography, plays an important role in the evaluation of functional salivary gland disorders • Indications – Evaluation of salivary gland function – Determine the size and location of the salivary glands – Detection and evaluation of mass lesions involving the salivary glands – Evaluation of the symptom of dryness of the mouth (xerostomia) • There are three bilateral pairs of major salivary glands – Parotid glands – Submandibular glands – Sublingual glands • The parotid glands are the largest of the salivary glands – Located anterior and inferior to the ear – Drain into the mouth through the Stenson ducts • The second pair is the submandibular glands – Located beneath the floor of the mouth – Empty directly into the mouth Accessory parotid gland Parotid duct Parotid gland Tongue Sublingual gland Submandibular duct External carotid arterySubmandibular gland
  22. 22. 22 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • The smallest of the salivary glands is the sublingual glands – Located beneath the tongue and are anterior to the submandibular glands • The salivary glands indiscriminately trap several ions, including 99mTc pertechnetate – These ions are also actively excreted by the glands into the saliva – Allows the evaluation the production and excretion of saliva – Dosage: 5 - 10 mCi (185 - 370 MBq) • For certain pathological conditions, 67Ga citrate is used for imaging – Inflammatory or neoplastic lesions – Sarcoidosis – Abscess – Determine if malignant – Lymphoma • For the acquisition, no special patient preparation is required – Some sites have the patient rinse his mouth to try to decrease early excretion of pertechnetate into the mouth • Acquisition guidelines – Low energy, high resolution or parallel hole collimator – Patient position: either supine or sitting with the detector positioned over the anterior face – Hyperextend the neck to prevent superimposition of the thyroid on the salivary glands – Inject the 99m Tc pertechnetate – Immediately acquire sequence of dynamic images to evaluate uptake phase ! 1-2 seconds/frame for 1 to 2 minutes to evaluate vascular phase ! 1-2 minutes/frame for 15 to 20 minutes to evaluate uptake phase – At 15 to 20 minutes post injection or when the glands are active, have your patient suck on sour candy or hold 1:1 dilution of lemon juice in mouth for 30 seconds (patient can swallow or expectorate the lemon juice into disposable container) ! Stimulates excretion of saliva – Continue imaging for another 10-20 minutes to evaluate the secretory phase – Images may also be acquired as a series of static images (300K-500K) at 2, 5, 10, 15, 30 and 30 minutes – In addition to the anterior views, acquire right and left lateral views with the head extended back slightly
  23. 23. 23 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 SALIVARY GLAND CASE REVIEW • Case 1: Sequence of the Salivary Gland Study • Case 2: Sjogren’s Syndrome • Case 3: Salivary Gland Tumor • Case 4: Gallium Imaging of Salivary Glands • Case 5: Lymphoma
  24. 24. 24 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 APPENDIX A: DVT IMAGING WITH ACUTECT • Acquisition parameters – Large field of view detector, single or dual head – Low energy, general purpose or high resolution parallel hole collimator – 15%-20% energy window centered around 140 keV – 128 x 128 acquisition matrix – Anterior and posterior static images ! Pelvis/thighs ! Knees ! Calves – Acquisition termination can be counts or time ! Minimum of 750K counts for pelvis ! Minimum of 500K counts for lower regions ! Typical acquisition time is 5 minutes/view – Acquire digital images • Patient preparation – Remove tight clothing, stockings or any lower extremity vascular compression devices – Ensure patient is well hydrated – Patient should void frequently during the first hours post-injection of the AcuTect and immediately prior to the study • Dosage – Peripheral intravenous injection in upper extremity – Approximately 100 µg of peptide radiolabeled with 20 mCi of technetium Tc-99m – An indwelling venous catheter or butterfly administration set may be used for the injection • Patient positioning – Proper patient positioning is essential for accurate image interpretation ! Ensure that patient alignment is maintained for all images acquired at all timepoints – Position patient supine on the imaging table – Use table guides to confirm straight limb position – Position the lower extremities symmetrically to allow comparison of early and late images ! It is advantageous to bind the feet together to stabilize the anterior-posterior position – Avoid flexion of the knees – Confirm that bedclothes, bedding, absorbent pads or pillows do not compress the limbs, especially behind the knees – Position urinary drainage catheters so they drain freely and are out of the field of view – To aid in patient positioning and in image interpretation, mark the right side of the patient in all images using a radioactive marker – Shield the urinary bladder – Confirm patient comfort to avoid motion during imaging
  25. 25. 25 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 • Image acquisition – Static images should be acquired using a fields of view that provide uninterrupted views of the thighs, knees and calves – Preferred fields of view for optimum image interpretation ! Pelvis and thighs: from the lower edge of the bladder to just above the knees ! Knees: from the mid-thigh to the mid-calf ! Calves: from just above the knees to just above the ankles – The full width of both legs should be in each view – Position the detector(s) as close to the patient as possible – Acquire two sets of images ! One set starting at 10 minutes post injection ! One set starting at 60 to 90 minutes post injection – Images should be acquired in the same sequence for each timepoint ! Preferred sequence: anterior pelvis/thighs, anterior knees, anterior calves, posterior pelvis/thighs, posterior knees, posterior calves – Repeat any image if patient moves during the acquisition • Image presentation – Preferably, the images should be presented digitally to allow image adjustment (brightness, contrast, and/or threshold and color) during interpretation – When formatting, images should be aligned by view for both timepoints to facilitate comparisons – If the images will be read from film, it is very important that the images be appropriately enhanced (by brightness, contrast, and/or threshold adjustment) to show asymmetric, deep venous AcuTect uptake if present, before generating the film • Source: AcuTect Image Atlas; 60-801880 September 1998; Diatide, Inc. and Nycomed Amersham
  26. 26. 26 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 APPENDIX B: TESTICULAR IMAGING • Indications – Evaluation of the patency of the blood supply to the testes – Evaluation of increased perfusion caused by inflammatory disease processes – Differentiation between acute epididymoorchitis and testicular torsion • Imaging agent – 99mTc pertechnetate – 15 mCi (555 MBq) adult dosage • No patient preparation is required • Acquisition guidelines – Place the patient in a supine position with legs abducted – Tape the penis up over the pubis to remove it from the field of view – Support the testes by placing a towel or pillow under the scrotum – Position the detector parallel and as close as possible to the scrotum – Inject the 99mTc pertechnetate – Immediately acquire dynamic images • 5 seconds/frame for 45 – 60 seconds – Acquire two anterior static images ! 500K – 1000K counts • If normal, symmetric perfusion of both testes should be seen
  27. 27. 27 of 27 © 2002 General Electric Company. All rights reserved. Learning Solutions from GE Medical Systems NM: Special Imaging Techniques Program Supplement REV 1 APPENDIX C: DACRYOCYSTOGRAPHY • Indications – Evaluation of the patency of the lacrimal duct – Evaluation for functional obstruction • Imaging agent – 99mTc pertechnetate – 200 µCi (7.4 MBq) per eye ! Dilute 10 mCi (370 MBq) of 99mTc pertechnetate to 0.5 ml with normal saline ! 10 drops delivers about 200 µCi (7.4 MBq) • No patient preparation is required • Acquisition guidelines – Place about 200 µCi (in the form of drops) in the affected eye or both eyes as requested – Quickly position the patient upright at a distance of 1.5 to 6 cm from the detector ! The distance will depend upon if one or both eyes are being imaged – Acquire 25K count static images at 0, 5, 10, and 15 minutes post administration • If normal, activity should be seen in the area of the nose by 10 to 15 minutes post administration

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