Christopher H. Hunt

Frequency and severity of adverse effects of iodinated and gadolinium contrast materials: retrospective review of 456,930 doses.

OBJECTIVE The purpose of this study was to determine the frequency and characteristics of adverse effects of low-osmolar iodinated and gadolinium contrast agents in a single-center experience with a large number of cases. MATERIALS AND METHODS A retrospective review of all intravascular doses of low-osmolar iodinated and gadolinium contrast materials administered from 2002 through 2006 was conducted. Adverse effects were identified through the use of radiologist and nurse event recording. Adverse effects were examined for type and severity of reaction, treatment required, and outcome. RESULTS A total of 456,930 contrast doses (298,491 low-osmolar iodinated, 158,439 gadolinium) were administered over the study period. A total of 522 cases of adverse effects (0.11% of total) were identified (458 low-osmolar iodinated, 64 gadolinium). The most common adverse effects were hives (274, 52.5%) and nausea (92, 17.6%). Of all adverse effects, 79 of low-osmolar iodinated and 15 of gadolinium contrast material necessitated treatment. Most treatments were performed in the radiology department alone. Only 16 cases of adverse effects necessitated transfer for further observation or treatment. Epinephrine was used to manage an adverse effect in nine instances. Thirty-two of the adverse effects of low-osmolar iodinated contrast material (6.9%) occurred in patients with a history of allergy who received premedication. Only two of these premedication reactions necessitated transfer to the emergency department. The one death in the study period occurred after administration of low-osmolar iodinated contrast material. The patient had no symptoms during the contrast administration or imaging but died suddenly within 30 minutes of receiving the dose. CONCLUSION Both iodinated and gadolinium contrast agents are associated with a very low rate of adverse effects. Most adverse effects are mild and can be managed in the radiology department. Transfer for additional treatment or observation is rarely needed.

Evidence-based guideline: Neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome

Introduction: The purpose of this study was to develop an evidence‐based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS). Methods: Two questions were asked: (1) What is the accuracy of median nerve cross‐sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2). Results: Neuromuscular ultrasound measurement of median nerve cross‐sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B). Muscle Nerve 46: 287–293, 2012

SUNCT Responsive to Gabapentin

SUNCT syndrome is characterized by episodes of short-lasting unilateral neuralgiform pain with conjunctival injection, tearing, and rhinorrhea. Described initially by Sjaastad et al in 1989, 1 the attacks involve moderately severe orbital pain which typically lasts between 10 and 120 seconds. The frequency of attacks varies from less than 1 attack per day to more than 30 per hour. This debilitating disorder is notable for its resistance to treatment, even with medications typically effective for patients with trigeminal neuralgia, cluster headache, or migraine. We describe a woman with SUNCT syndrome that was exquisitely sensitive to gabapentin.

The role of MR myelography with intrathecal gadolinium in localization of spinal CSF leaks in patients with spontaneous intracranial hypotension.

BACKGROUND AND PURPOSE: Localization of spinal CSF leaks in CSF hypovolemia is critical in directing focal therapy. In this retrospective review, our aim was to determine whether GdM was helpful in confirming and localizing spinal CSF leaks in patients in whom no leak was identified on a prior CTM. MATERIALS AND METHODS: Forty-one symptomatic patients with clinical suspicion of SIH were referred for GdM after undergoing at least 1 CTM between February 2002 and August 2010. A retrospective review of the imaging and electronic medical records was performed on each patient. RESULTS: In 17 of the 41 patients (41%), GdM was performed for follow-up of a previously documented leak at CTM. In the remaining 24 patients (59%), in whom GdM was performed for a suspected CSF leak, which was not identified on CTM, GdM localized the CSF leak in 5 of 24 patients (21%). In 1 of these 5 patients, GdM detected the site of leak despite negative findings on brain MR imaging, spine MR imaging, and CTM of the entire spine. Sixteen of 17 patients with previously identified leaks underwent interval treatment, and leaks were again identified in 12 of 17 (71%). CONCLUSIONS: GdM is a useful technique in the highly select group of patients who have debilitating symptoms of SIH, a high clinical index of suspicion of spinal CSF leak, and no demonstrated leak on conventional CTM. Intrathecal injection of gadolinium contrast remains an off-label use and should be reserved for those patients who fail conventional CTM.

When Should I Do Dynamic CT Myelography? Predicting Fast Spinal CSF Leaks in Patients with Spontaneous Intracranial Hypotension

Which patients with intracranial hypotension will need dynamic CT myelography? The authors assessed brain and spine MRI studies and opening pressure measurements in 150 consecutive patients with intracranial hypotension to see if these can predict fast CSF spine leaks that will require dynamic myelography. Fast leaks were present in 21% and correlated well with the presence of spinal extra-arachnoid fluid. No correlation between fast leaks and brain MRI findings was found. Thus, when spinal extra-arachnoid fluid is documented on MRI studies there is no need for conventional CT myelography but the patient should be directly studied with dynamic CT myelography. BACKGROUND AND PURPOSE: Some patients with SIH have fast CSF leaks requiring dynamic CTM for localization; however, patients generally undergo conventional CTM before a dynamic study. Our aim was to determine whether findings on head MR imaging, spine MR imaging, or opening pressure measurements can predict fast spinal CSF leaks. MATERIALS AND METHODS: A retrospective review was performed on 151 consecutive patients referred for CTM to evaluate for spinal CSF leak. Head MR imaging was evaluated for diffuse dural enhancement and “brain sag,” and spine MR imaging for presence of an extradural fluid collection. The opening pressure was recorded. The CTM was scored as no leak, slow leak localized on conventional CTM, or fast leak that required dynamic CTM. RESULTS: Fast CSF leaks were identified in 32 (21%), slow leaks in 36 (24%), and no leak in 83 (55%) of 151 patients on initial CTM. There was significant association between spinal extra-arachnoid fluid on MR imaging and the presence of a fast leak (sensitivity 85%, specificity 79%, P < .0001). There was not significant association between fast leak and findings on head MR imaging (P = .27) or opening pressure (P = .30). CONCLUSIONS: If all patients with spinal extra-arachnoid CSF on MR imaging had been sent directly to dynamic CTM, repeat myelography would have been avoided in most patients with fast leaks (23 of 27; 85%). However, a minority of patients with slow or no leaks would have been converted from conventional to dynamic CTM (16 of 77; 21%). Spinal MR imaging is helpful in premyelographic evaluation of SIH.

ACR Appropriateness Criteria Low Back Pain.

Most patients presenting with uncomplicated acute low back pain (LBP) and/or radiculopathy do not require imaging. Imaging is considered in those patients who have had up to 6 weeks of medical management and physical therapy that resulted in little or no improvement in their back pain. It is also considered for those patients presenting with red flags raising suspicion for serious underlying conditions, such as cauda equina syndrome, malignancy, fracture, and infection. Many imaging modalities are available to clinicians and radiologists for evaluating LBP. Application of these modalities depends largely on the working diagnosis, the urgency of the clinical problem, and comorbidities of the patient. When there is concern for fracture of the lumbar spine, multidetector CT is recommended. Those deemed to be interventional candidates, with LBP lasting for > 6 weeks having completed conservative management with persistent radiculopathic symptoms, may seek MRI. Patients with severe or progressive neurologic deficit on presentation and red flags should be evaluated with MRI. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (the RAND/UCLA Appropriateness Method and the Grading of Recommendations Assessment, Development, and Evaluation) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Pitfalls and Artifacts

FDG PET is extremely useful in staging and restaging cancer, differentiating malignant from benign processes, and locating otherwise occult sites of malignancy. However, areas of real or apparent FDG activity do not always represent malignancy. In this chapter we will review the more common categories of pitfalls and artifacts and how they can be recognized and avoided. Pitfalls arise when real benign biologic processes result in imaging findings that mimic malignancy. Common pitfalls are seen with abnormal nonmalignant biologic processes, as well as normal physiologic and anatomic variation. Artifacts are imaging findings that arise in the process of patient preparation and imaging. Artifacts can mimic real biologic processes, or can negatively affect the interpretation of real biologic processes. Common artifacts result from errors related to attenuation correction, motion, truncation, glucose and insulin, FDG injection and uptake. When combining PET and CT imaging, some pitfalls and artifacts are avoided, while others may be newly created or multiplied.

Intramedullary Spinal Cord Metastases: MRI and Relevant Clinical Features From a 13-Year Institutional Case Series

This article reviews the MRI and clinical findings in 70 spinal cord metastases; 20% of patients had multiple metastases and 8% were asymptomatic. Spinal cord metastases were the initial clinical presentation in 20% of patients. Nearly all metastases showed contrast enhancement and had extensive edema. Cysts and hemorrhage were, however, uncommon and nearly 60% of patients had other metastases to the CNS or that were seen in studies in other organs. Accompanying pial metastases were also common. BACKGROUND AND PURPOSE: Because intramedullary spinal cord metastasis is often a difficult diagnosis to make, our purpose was to perform a systematic review of the MR imaging and relevant baseline clinical features of intramedullary spinal cord metastases in a large series. MATERIALS AND METHODS: Consecutive patients with intramedullary spinal cord metastasis with available pretreatment digital MR imaging examinations were identified. The MR imaging examination(s) for each patient was reviewed by 2 neuroradiologists for various imaging characteristics. Relevant clinical data were obtained. RESULTS: Forty-nine patients had 70 intramedullary spinal cord metastases, with 10 (20%) having multiple intramedullary spinal cord metastases; 8% (4/49) were asymptomatic. Primary tumor diagnosis was preceded by intramedullary spinal cord metastasis presentation in 20% (10/49) and by intramedullary spinal cord metastasis diagnosis in 10% (5/49); 98% (63/64) of intramedullary spinal cord metastases enhanced. Cord edema was extensive: mean, 4.5 segments, 3.6-fold larger than enhancing lesion, and ≥3 segments in 54% (37/69). Intratumoral cystic change was seen in 3% (2/70) and hemorrhage in 1% (1/70); 59% (29/49) of reference MR imaging examinations displayed other CNS or spinal (non–spinal cord) metastases, and 59% (29/49) exhibited the primary tumor/non-CNS metastases, with 88% (43/49) displaying ≥1 finding and 31% (15/49) displaying both findings. Patients with solitary intramedullary spinal cord metastasis were less likely than those with multiple intramedullary spinal cord metastases to have other CNS or spinal (non–spinal cord) metastases on the reference MR imaging (20/39 [51%] versus 9/10 [90%], respectively; P = .0263). CONCLUSIONS: Lack of known primary malignancy or spinal cord symptoms should not discourage consideration of intramedullary spinal cord metastasis. Enhancement and extensive edema for lesion size (often ≥3 segments) are typical for intramedullary spinal cord metastasis. Presence of cystic change/hemorrhage makes intramedullary spinal cord metastasis unlikely. Evidence for other CNS or spinal (non–spinal cord) metastases and the primary tumor/non-CNS metastases are common. The prevalence of other CNS or spinal (non–spinal cord) metastases in those with multiple intramedullary spinal cord metastases is especially high.

Preliminary study of the use of drug-eluting stents in atherosclerotic renal artery stenoses 4 mm in diameter or smaller.

PURPOSE To describe restenosis and clinical outcomes with drug-eluting stents (DESs) and compare them to those of bare metal stents (BMSs) in the treatment of symptomatic atherosclerotic renal artery stenosis (RAS) in the same patients. METHODS AND MATERIALS A retrospective study was performed of all patients with RAS treated with a DES (Taxus Express 2 or Cypher). DESs were used for RASs with luminal vessel diameters of 4 mm or smaller and BMSs were used for those larger than 4 mm. RESULTS Sixteen patients (eight women; mean age, 72 years +/- 8) underwent treatment of 27 RASs for worsening renal function (n = 10) and uncontrolled hypertension (n = 6). Eighteen RASs were treated with 23 DESs (Cypher, n = 12; Taxus, n = 11) and nine were treated with BMSs. The average follow-up was 22 months +/- 10. After the procedure, the mean systolic blood pressure decreased significantly (P < .05), with no change in the mean diastolic pressure, serum creatinine, or number of antihypertensive medications. By Kaplan-Meier estimates, the 1- and 2-year patency rates for DESs were 78% and 68%, respectively; and for BMSs, the respective rates were 58% and 47% (P = NS). The average diameters of RASs were 3.4 mm +/- 0.6 in the DES group and 5.3 mm +/- 0.6 in the BMS group (P < .05). There were two technical failures (7.7%) in the DES group. There was one minor complication and a non-flow-limiting dissection. CONCLUSIONS DESs were used to treat RASs with good technical results and low restenosis rates compared with BMSs despite the smaller artery diameters in the DES group.

The Added Value of 18F-FDG PET/CT for Evaluation of Patients with Esthesioneuroblastoma

The purpose of this study was to evaluate the clinical utility of 18F-FDG PET/CT in esthesioneuroblastoma staging and restaging and quantify the additional benefit of PET/CT to conventional imaging. Methods: A retrospective review was performed with institutional review board approval for patients with a diagnosis of esthesioneuroblastoma who underwent PET/CT from 2000 to 2010. PET/CT results were retrospectively reviewed by 2 radiologists who were unaware of the clinical and imaging data. Positive imaging findings were classified into 3 categories: local disease, cervical nodal spread, and distant metastasis. All conventional imaging performed in the 6 mo preceding PET/CT, and the medical records, were reviewed to determine the potential added value. Results: Twenty-eight patients (mean age, 52.3 ± 10 y; range, 23–81 y) were identified who underwent a total of 77 PET/CT examinations. Maximum standardized uptake value (SUVmax) was 8.68 ± 4.75 (range, 3.6–23.3) for the primary tumor and 8.57 ± 6.46 (range, 1.9–27.2) for the metastatic site. There was no clear association between primary tumor SUVmax and tumor grade (P = 0.30). Compared with conventional imaging, PET/CT changed disease stage or altered clinical management in 11 (39%) of 28 esthesioneuroblastoma patients. Of these, 10 (36%) of 28 were upstaged on the basis of their PET/CT studies. Cervical nodal metastases were found in 5 (18%) of 28, local recurrence in 2 (7%) of 28, cervical nodal and distant metastases in 2 (7%) of 28, and distant metastases in 1 (4%) of 28. One patient (4%) was downstaged after negative findings on PET/CT. Conclusion: PET/CT is a useful adjunct to conventional imaging in the initial staging and restaging of esthesioneuroblastoma by detecting nodal and distant metastatic disease not demonstrated by conventional imaging and identifying local recurrence hidden by treatment changes on conventional imaging.