VP Shunt PatencyAmanda Sachs, R.T. (MR)

Nuclear Medicine Technology Directed Practice III

College of Allied Health SciencesUniversity of Cincinnati

Anatomy Overview

★ What is “VP”?○ Ventriculoperitoneal

■ shunt moves CSF from the ventricles to the peritoneum in the abdominal cavity where it can be absorbed

★ CSF shunts are placed, usually at a young age, to treat symptoms of hydrocephalus○ the shunt moves excess CSF fluid out of the ventricles

to decrease the amount of CSF in the brain, thus decreasing hydrocephalus

★ “The shunt system consists of a reservoir with a valve placed beneath the soft tissues of the head, a proximal (afferent) tubing line leading from one of the ventricles to the reservoir, and a distal (efferent) tubing line leading from the reservoir to the peritoneal cavity” (Macdonald & Burrell, 2009)

All about shunts

Indications★ Suspect of a malfunctioning CSF

shunt○ hydrocephalus-related symptoms

■ increase in intracranial pressure ■ mental instability ■ urinary incontinence■ gait instability■ headaches■ coma■ and many others

★ If patient has a possibility of current infection or general illness, VP shunt study should be delayed until patient is well again due to the risk of meningitis and other infection

★ Patient should not be pregnant or breastfeeding○ Female patients of childbearing age must be able

to prove they are not pregnant (by institutional policy)

○ If breast feeding, patient must make special preparations ahead of time

★ Any recent nuclear medicine studies using Tc-99m or In-111 may interfere with this study

Contraindications

★ Area of the injection site (over the shunt reservoir) must be shaved and cleansed

★ “A focused history containing the following elements should be obtained:○ History of neurologic procedures, including

shunt○ History of hydrocephalus or seizures○ symptoms of head pressure or pain○ Problems with balance or memory○ Results of other diagnostic tests” (Farrell, et

al.)★ No diet or medication restrictions

Patient Preparation

★ Tc-99m DTPA (preferred), In-111 DTPA, or, rarely,Tc-99m pertechnetate may be used for imaging of shunts○ Tc-99m DTPA

■ 0.5mCi (0.5-1.0mCi) ● technically Tc-99m DTPA is not approved for

intrathecal injections and “should be used with caution” (Farrell, et al.)

○ In-111 DTPA■ 75-300 uCi (depending on the the site of the

shunt)

Radiopharmaceutical Information

★ Dose administered by a physician★ Patient is sitting upright★ Injected intrathecally into shunt

○ through rubber reservoir of shunt■ usually located: on the right side of the head;

behind the ear, on top of the head, or the posterior portion of the head; and usually a few centimeters below where the initial incision site during surgery was.

○ a small amount, bolus, is all that may be injected as “to ensure minimal disruption of the normal CSF flow” (Macdonald & Burrell, 2009).■ 0.3-0.5ml

○ CSF should NOT be removed by a syringe during this procedure

Radiopharmaceutical Administration

★ Patient Supine after injection★ Immediate pictures

○ Anterior and Laterals○ centered over head○ 1 minute picture○ special attention to number of counts in that 1 minute

★ Marker Picture○ Lateral

■ slowly trace a radiopharmaceutical marker around the scalp■ also place marker on each canthus (outside corner of the eyes) for a few

seconds○ Repeat for Anterior

★ Anterior pictures every 2 minutes for 10 minutes★ Anterior Images every 5 minutes for at least 20 minutes

○ alternating between imaging the abdomen (where the shunt empties) and the head

★ “If activity is not passing down the tube [or] is not clearing, the patient should be placed in an upright position and/or the shunt should be pumped” and the series of images would be repeated

per University Hospital protocol

Imaging Protocol (In-111 DTPA)

★ Photopeaks at 173 and 247 keV★ 15% window★ Medium Energy High Resolution Collimators★ 128 x 128 Matrix

per University Hospital

Acquisition Parameters(In-111 DTPA)

★ 30 minute dynamic study○ 60 images 30 seconds each or 1

minute/frame for 20 minutes○ Anterior images

★ Planar 10 minutes/view

Imaging Protocol (Tc-99m DTPA)

★ LFOV camera★ Low Energy High Resolution

collimators★ photopeak at 140 keV

○ 20% window★ 128 x 128 matrix

Acquisition Parameters (Tc-99m DTPA)

★ activity in shunt reservoir

★ activity along entire course of shunt tubing into the peritoneal cavity

★ In Tc-99m DTPA, kidney visualization is normal for shunt patency

Normal vs. Abnormal Study★ reflux into

ventricles of the brain

★ early termination of shunt tubing activity

★ any signs of obstruction

NormalImages

Abnormal

★ “Sum the dynamic images and display for optimal visualization of the area of interest” (Farrell, et. al)

★ Processing these images involves labeling the markers (scalp, canthus, etc.)

★ Images should be inverted so that hot areas are dark and background is lighter

★ Label the area imaged on display page○ examples: Anterior head, anterior abdomen,

Lateral chest, etc.★ Label the times of the images

Processing

Campellone, J. (2013, October 29). Ventriculoperitoneal shunting (D. Zieve, Ed.). Retrieved July 17, 2015, from http://www.nlm.nih.gov/medlineplus/ency/article/003019.htm

CSF Shunt Scintigraphy. (2014, October 1). Retrieved July 8, 2015, from http://www.sh.lsuhsc.edu/raddept/pdf/sec18/Rad Proc 18.8.7.6.pdf

Farrell, M., Mantel, E., Basso, D., Thomas, K., & Kerr, B. (n.d.). Quick-reference protocol manual for nuclear medicine technologists.

Hydrocephalus and Ventriculoperitoneal (VP) Shunt [Medical Illustration]. Retrieved from http://findlaw.doereport.com/generateexhibit.php?ID=9550&ExhibitKeywordsRaw=&TL=&A=42409

Macdonald, A., & Burrell, S. (2009). Infrequently Performed Studies in Nuclear Medicine: Part 2. Journal of Nuclear Medicine Technology, 1-3. Retrieved July 8, 2015, from http://interactive.snm.org/docs/Infrequently%20Performed%20Studies%20Part%202.pdf

Nuclear Medicine Shunt Patency. (n.d.). Retrieved July 7, 2015, from http://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/hydrocephalus/procedures/nuclear_medicine_shunt.html

University Hospital

Ventriculoperitoneal Shunt Tap. (n.d.). Retrieved July 17, 2015, from http://emedicine.medscape.com/article/81058-overview#a6

Ventriculoperitoneal Shunt. (n.d.). Retrieved July 17, 2015, from http://www.fpnotebook.com/Neuro/Surgery/VntrclprtnlShnt.htm

References