Indium-111 diethylene-triamine-pentaacetic acid scintigraphy in the evaluation of function and patency of baclofen intrathecal infusion systems

Isotopic Scintigraphy in Intrathecal Drug Delivery Failure: A Single-Institution Case Series

Background

The aim of this study was to assess the feasibility and diagnostic accuracy of an optimized ¹¹¹Indium‐diethylenetriamine‐penta‐acetic‐acid single‐photon‐emission computed tomography (CT) (¹¹¹In‐DTPA SPECT‐CT) examination in patients with suspected intrathecal drug delivery (ITDD) failure.

Materials and Methods

Retrospective analysis of routinely collected observational data from a case series of patients in the setting of the academic Center for Pain Medicine, Departments of Radiology and Nuclear Medicine and Neurosurgery. Twenty‐seven patients participated between January 2014 and January 2019. Thirty‐six optimized examinations including standardized pump flow rate with additional SPECT‐CT imaging and a stepwise standardized analysis were performed. A 10 mL mixture of medication and 20 MBq 111In‐DTPA was injected into the pump reservoir. Planar and SPECT‐CT images were acquired at 24, 48, and 72 hours (h) after injection and at 96 hours and/or seven days, if needed. All images were reassessed by the first two authors using an optimized procedure.

Results and Conclusions

Twenty‐two abnormalities were identified in 21 examinations, with these abnormalities consisting of leakage (n = 7), spinal catheter obstruction (n = 7), and cerebrospinal fluid flow obstruction (n = 8). Interventions (n = 19) confirmed the cause of ITDD failure. A false‐positive finding at follow‐up (n = 1) and a false‐negative finding (n = 1) were encountered. Sensitivity was 95% (20/21) and the specificity 93% (14/15). A significant difference (p < 0.001) was found between the accuracy of the conventical and the optimized analysis. The optimized ¹¹¹In‐DTPA SPECT‐CT examination is a powerful diagnostic tool for detecting the cause of ITDD failure.

Catheter Access Port (Computed Tomography) Myelography in Intrathecal Drug Delivery Troubleshooting: A Case Series of 70 Procedures

Objectives

Intrathecal drug delivery is used for the treatment of intractable spasticity, dystonia, and pain. When the symptomatology fails to respond to therapy, the cause could be failure of the medication infusion. The purpose of this study is to assess pump catheter access port (CAP)‐myelography and CAP‐CT‐myelography as advanced imaging methods in treatment failure.

Materials and Methods

We analyzed observational routinely collected data of 70 CAP procedures with 2D/3D reconstructions and additional imaging of 53 adult patients where the cause of treatment was unclear between November 2013 and November 2018. CAP‐myelography and CAP‐CT myelography were performed with postprocessing 2D/3D reconstructions. When myelography could not be obtained or when the result did not reveal the cause of the treatment failure, additional procedures, such as noncontrast CT, MRI, lumbar puncture CT, and 111Indium‐DTPA SPECT‐CT, were performed.

Results

CAP fluid aspiration prior to contrast medium injection was not possible (N = 17). In one case, contrast was injected into the pump pocket unintentionally (N = 1). Of 70 procedures, 24% were unaspiratable. The remaining CAP myelography examinations (N = 52) had limited value for the diagnosis. CAP‐CT myelography (N = 50) was normal (N = 31). The abnormal results (N = 19) were dorsal dural leak (N = 5), subdural catheter position (N = 2), limited rostral flow of contrast material (N = 4), limited and abnormal contrast distribution (N = 3), obstruction of rostral flow (N = 2), a leak at the pump‐catheter connection (N = 1), and a sheared catheter localized in the pump pocket (N = 2). Limited contrast distributions were found to be false positive findings (N = 2). Four normal CT‐CAP myelographic procedures were false negatives, as the reference tests revealed a cause of intrathecal drug delivery (ITDD) failure. The CAP‐CT procedures resulted in a sensitivity of 81% (17/21) and a specificity of 93% (27/29).

Conclusions

CAP‐CT myelography with 2D/3D reconstructions is an essential step in the diagnostic algorithm for cases involving ITDD failure.

Evaluation of intrathecal baclofen delivery system malfunction by computed tomography scan

AIM

To describe the computed tomography (CT) findings encountered when catheter patency is questionable. The role of CT in directing treatment is evaluated.

METHOD

Records of children with intrathecal baclofen pump management were reviewed. Only patients with CT evaluation who had revision pump/catheter surgery were included.

RESULTS

From 295 patients, 27 had CT contrast study; in three of them, baclofen could not be aspirated and the procedure was stopped, eight had normal scan and did not need surgery and 16 patients were reported. Four patients had normal CT (free contrast formed a perfect crescent shape), and had surgery because the pump battery was close to expiration. Five patients had inadequate fluid pooling (fluid was seen without a crescent shape). Five patients had fluid leak (fluid was seen around the pump or in the lumbar canal below catheter entrance level or outside the canal in the lumbar region). Two patients had catheter occlusion (fluid loculation around the catheter tip with no free flow).

INTERPRETATION

CT contrast study is safe and effective for locating defects in intrathecal baclofen delivery system. When catheter patency is questionable, CT plays an important role in directing the next step of management.

Isotopic Scintigraphy Coupled With Computed Tomography for the Investigation of Intrathecal Baclofen Device Malfunction

OBJECTIVE

To assess the potential use of indium-111 diethylenetriamine pentaacetic acid ((111)In-DTPA) scintigraphy coupled with computed tomography (CT) for the investigation of intrathecal baclofen (ITB) device malfunction.

DESIGN

Retrospective study of a case series of patients.

SETTING

Neurosurgical and physical and rehabilitation medicine departments.

PARTICIPANTS

Patients (N=7) with reduced ITB effectiveness in whom prior conventional radiographs were inconclusive.

INTERVENTION

Nine (111)In-DTPA scintigraphic studies and 8 CT scans. Planar acquisitions were followed by tomoscintigraphy combined with CT.

MAIN OUTCOME MEASURE

Progression of the radiotracer in the pump, catheters, and in the subarachnoid space.

RESULTS

In 7 cases, scintigraphy coupled with CT showed leakage behind the pump, lack of activity outside the pump reservoir, abrupt interruption of activity in the catheter, or abnormal distribution of the radiotracer, thus demonstrating that the drug did not reach its target. Surgical revision confirmed these findings in 5 cases. In 1 case, combined imagery ruled out device dysfunction. In the remaining case, only planar acquisitions were performed, showing correct diffusion of the radiotracer.

CONCLUSIONS

The combination of scintigraphy and CT provides simultaneous functional and anatomic imagery of the device. The slow infusion of the radioisotope mimics the diffusion of baclofen, and this could be a useful method to explore intrathecal device malfunction. Further studies are required to compare scintigraphy coupled with CT, to radiopaque injection followed by fluoroscopy or CT.

Evaluation of usefulness of scintigraphic imaging in diagnosis of intrathecal drug delivery system malfunction - a preliminary report

BACKGROUND

Implantable intrathecal drug delivery systems (IDDS) are basic tool enabling chronic intrathecal pharmacotherapy. Lack of expected clinical results of IDDS therapy necessitates search for the cause with the help of diagnostic imaging methods among other things. Beside radiological techniques, it is also possible to visually assess IDDS systems by nuclear medicine methods. In this study we assess utility of radioisotopic methods in differential diagnosis of failure of therapy with IDDS systems.

MATERIAL/METHODS

Scintigraphic studies were performed in selected patients with neurological diseases associated with spasticity, who had IDDS system implanted and were unable to maintain satisfying clinical effect of inrathecally infused baclofen. After emptying the IDDS system of the drug, radiotracer (99mTc-DTPA) solution was injected into the pump reservoir. Subsequently, a series of scintigraphic images was registered, demonstrating passage and distribution of the infused radiotracer.

RESULTS

In all investigated cases, scintigraphic study resulted in acquiring relevant additional diagnostic information. Normal or disrupted distribution of radiotracer in spinal canal allowed for a diagnosis drug resistance or demonstrated presence of arachnoid adhesions respectively. Early appearance of radiotracer in blood was considered a proof of leak. Our examinations had decisive influence on further patient treatment, allowing for diagnosis of drug resistance in one patient or complication related to IDDS system in three other cases including breakage of a catheter, pump malfunction and arachnoid adhesions.

CONCLUSIONS

Scintigraphic methods carry significant amount of information facilitating final diagnosis of the cause of IDDS therapy failure. They should become an important element complementing the diagnostic strategy in patients with suspected failure of intrathecal drug administration systems. Interpretation of radioisotopic studies, since they are purely functional, must be performed in strict relation to clinical data and radiological examinations as they carry indispensable, basic information regarding morphology.

Indium 111 diethylenetriamine pentaacetic acid scintigraphy in the identification and management of intrathecal pump malfunction

BACKGROUND

Intrathecal drug-delivery systems have become widely used tools in the management of refractory chronic pain and spasticity. Because increasing numbers of patients are using these systems, rehabilitation specialists frequently are the initial care providers who identify clinical signs and symptoms indicating possible complications relating to the implanted system. Identification of a pump malfunction often presents a diagnostic challenge. Distinguishing among progression of disease, new organic problems, and/or drug-device complications is critical. The use of nuclear medicine indium 111 diethylenetriamine pentaacetic acid (DTPA) studies represents a highly effective, straightforward, minimally invasive way to assess implant function and drug distribution.

OBJECTIVE

To identify patients with suspected intrathecal pump malfunction and to determine whether the use of indium 111 DTPA is effective in identifying the source of failure.

DESIGN

A retrospective review was performed from 2011 to 2012.

SETTING

The study was performed at Georgia Health Sciences University.

PATIENTS

The 23 selected patients had implanted devices for either spasticity or pain and were experiencing symptoms of a possible pump malfunction despite normal radiographic imaging. Twenty-four scintigraphic studies were performed, with malfunction documented in 19 patients.

METHODS

A standard refill technique was used to inject 0.3 mL of indium 111 DTPA into the pump reservoir. Radionuclide images were reviewed at varying time points up to 48 hours after injection. The extent of radionuclide progression from the pump reservoir to the intrathecal space was evaluated. In cases in which a problem with the implant was identified, correlation with operative findings is described.

RESULTS

Normal results of studies ultimately correlated with other clinical issues and confirmed an alternative etiology for the clinical changes noted. In studies with abnormal results, several patterns of failure were identified: restriction of the radionuclide to the pump reservoir, extravasations of tracer into the pump subcutaneous pocket, failure of the tracer to migrate from the subcutaneous catheter to the intrathecal space, and pooling of the tracer in the subcutaneous tissues. In all cases, surgical findings confirmed the suspected mechanism of malfunction as determined by the study.

CONCLUSIONS

Indium 111 DTPA scintigraphy is a safe, straightforward way to identify and characterize clinical changes associated with intrathecal drug-delivery systems and to guide appropriate and clinical surgical management.

Combined C-arm fluoroscopy and C-arm cone beam computed tomography for the evaluation of patients with possible intrathecal baclofen delivery system malfunctions

BACKGROUND

Evaluating intrathecal baclofen (ITB) delivery systems for potential malfunction can be challenging. The catheter systems are prone to myriad complications that are frequently difficult to ascertain by conventional imaging techniques. Newer imaging technologies and their combinations can be used to identify such problems, define surgical indications, and focus operative planning. C-arm fluoroscopy and C-arm cone beam CT performed in one imaging session represents one such combination that has great utility.

OBJECTIVE

We present a case series of ITB catheter evaluations using combined C-arm fluoroscopy (CF) and C-arm cone beam CT (CCBCT).

METHODS

We retrospectively analyzed 7 pediatric patients who underwent ITB catheter systems evaluations by the use of combined CF and CCBCT. Study variables included indications for evaluation, imaging results, interventions, correlation of surgical findings with imaging, and clinical outcome.

RESULTS

Three patients had intact and patent catheter systems. Four patients demonstrated various problems of the catheter systems, including disconnection, microfracture, fracture with segment migration, and subdural migration. Dosage adjustments improved all patients with normal studies. Surgery was guided by the imaging, and all operative patients improved after targeted interventions. Intraoperative findings correlated perfectly with imaging.

CONCLUSION

Combined CF and CCBCT proved highly effective in the evaluation of our patients with potential ITB system malfunctions. This technique is advocated for such evaluations because it accurately defines problems with connectivity, integrity, and position of catheter systems. When surgical intervention is required, this information aids in operative planning.

Imaging evaluation of intrathecal baclofen pump-catheter systems

ITB pumps are widely used in the treatment of intractable spasticity for many clinical indications, including cerebral palsy and spinal cord injury. High-dose intrathecal administration places the patient at significant risk for withdrawal in the event of device malfunction, necessitating rapid and complete evaluation of the pump-catheter system. This article reviews the approach to imaging evaluation of ITB pump-catheter systems, with specific emphasis on radiography, fluoroscopy, CT, and nuclear scintigraphy.