Imaging recommendations for acute stroke and transient ischemic attack patients: A joint statement by the American Society of Neuroradiology, the American College of Radiology, and the Society of NeuroInterventional Surgery.

SUMMARY: Stroke is a leading cause of death and disability worldwide. Imaging plays a critical role in evaluating patients suspected of acute stroke and transient ischemic attack, especially before initiating treatment. Over the past few decades, major advances have occurred in stroke imaging and treatment, including Food and Drug Administration approval of recanalization therapies for the treatment of acute ischemic stroke. A wide variety of imaging techniques has become available to assess vascular lesions and brain tissue status in acute stroke patients. However, the practical challenge for physicians is to understand the multiple facets of these imaging techniques, including which imaging techniques to implement and how to optimally use them, given available resources at their local institution. Important considerations include constraints of time, cost, access to imaging modalities, preferences of treating physicians, availability of expertise, and availability of endovascular therapy. The choice of which imaging techniques to employ is impacted by both the time urgency for evaluation of patients and the complexity of the literature on acute stroke imaging. Ideally, imaging algorithms should incorporate techniques that provide optimal benefit for improved patient outcomes without delaying treatment.

Positron emission tomography/computed tomography imaging for the detection of recurrent ovarian and fallopian tube carcinoma: a retrospective review.

PURPOSE: Imaging modalities to evaluate ovarian/fallopian tube cancer patients for recurrence are limited. Positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound lack the sensitivity to consistently detect recurrence or measurable disease in these patients. A new technique combines PET and CT (PET/CT) images to identify increased metabolic activity and to locate that signal with improved anatomic specificity. The objective of this study is to compare PET/CT, CT, and histologic findings in patients with recurrent ovarian/fallopian tube cancers. METHODS: Retrospective chart review of eight patients with primary ovarian (n = 6) or fallopian tube (n = 2) cancer was performed. All eight patients underwent initial cytoreductive surgery. Five patients initially received chemotherapy, one received radioactive phosphorus ((32)P), one received tamoxifen, and one received no therapy. Seven of eight patients had a suspected recurrence based on clinical examination, elevated CA-125 level, and/or abnormal CT findings; one patient requested a PET/CT. Histologic findings from surgery were correlated with PET/CT and CT findings. RESULTS: All eight patients had positive histology, and of these, seven patients had a negative CT and five patients had lesions that were correctly identified by PET/CT. CONCLUSIONS: Five of the eight (62%) patients had recurrent disease based on correlative histology with a positive PET/CT and a negative CT. These preliminary findings suggest that combined PET/CT may be an effective means of identifying patients with recurrent ovarian/fallopian tube cancer. Such patients could potentially proceed to salvage treatment and avoid the morbidity and expense of surgical assessment. Pilot studies comparing CT, PET, PET/CT, and histologic findings are underway.

Venous angioma adjacent to the root entry zone of the trigeminal nerve: implications for management of trigeminal neuralgia.

Detection of a venous angioma at the root entry zone is important for surgical planning, so that the neurosurgeon will be aware that both veins and arteries may require microvascular decompression. In selected cases, alternative treatment may be indicated to avoid the potential surgical complication of a venous infarct. Trigeminal neuralgia typically occurs in the middle-aged to elderly population, usually the result of compression of the trigeminal nerve at its root entry zone by an ectatic, aging artery or, less commonly, a regional vein [1, 2, 3]. When associated with a venous angioma at the root entry zone, trigeminal neuralgia usually presents at a younger age [4, 5, 6]. We review the imaging examinations and clinical data of five patients with trigeminal neuralgia who had a venous angioma adjacent to the root entry zone of the trigeminal nerve, and discuss how the imaging findings affected their management.

Effects of bupropion SR on anterior paralimbic function during waking and REM sleep in depression: preliminary findings using.

This study sought to clarify the effects of bupropion SR on anterior paralimbic function in depressed patients by studying changes in the activation of these structures from waking to REM sleep both before and after treatment. Twelve depressed patients underwent concurrent EEG sleep studies and [18F]fluoro-2-deoxy-D-glucose ([18F]-FDG) positron emission tomography (PET) scans during waking and during their second REM period of sleep before and after treatment with bupropion SR. Nine subjects completed pre- and post-treatment waking PET studies. Five subjects completed pre- and post-treatment waking and REM sleep PET studies. Bupropion SR treatment did not suppress electrophysiologic measures of REM sleep, nor did it alter an indirect measure of global metabolism during either waking or REM sleep. Bupropion SR treatment reversed the previously observed deficit in anterior cingulate, medial prefrontal cortex and right anterior insula activation from waking to REM sleep. In secondary analyses, this effect was related to a reduction in waking relative metabolism in these structures following treatment in the absence of a significant effect on REM sleep relative metabolism. The implications of these findings for the relative importance of anterior paralimbic function in REM sleep in depression and for the differential effects of anti-depressant treatment on brain function during waking vs. REM sleep are discussed.

The role of positron emission tomography in evaluating mediastinal lymph node metastases in non-small-cell lung cancer.

Positron emission tomography (PET) is a modality that differentiates malignant from benign processes based upon metabolism rather than anatomy. A number of studies have confirmed improved accuracy of PET over computed tomography (CT), but until a few recent studies, most had failed to include satisfactory histologic confirmation. The objective of this study was to compare PET and CT to histologic staging of the mediastinum in patients with non-small-cell lung cancer (NSCLC). Histologic examination of mediastinal lymph nodes (MLNs) was performed on 40 patients with NSCLC at mediastinoscopy and/or at surgical resection. PET scans were interpreted by one of two nuclear medicine physicians, blinded to histology, using CT scans for anatomic localization. CT scans were independently evaluated for mediastinal lymphadenopathy. The overall accuracy, sensitivity, and specificity of PET were 78% (31 of 40), 67% (four of six), and 79% (27 of 34), respectively. The overall accuracy, sensitivity, and specificity of CT were 68% (27 of 40), 50% (three of six), and 71% (24 of 34), respectively. PET was superior to CT at correctly identifying mediastinal nodal metastases; however, both modalities were inferior to the gold standard of surgical staging. PET is more accurate than CT in staging the mediastinum of patients with NSCLC. PET failed to identify lymph node metastasis in 33% of patients with histologically proven MLN involvement, and false positives were present in 15%. At present, mediastinoscopy should remain the standard of care for preoperative mediastinal staging for NSCLC.

Whole-body FDG positron emission tomographic imaging for staging esophageal cancer comparison with computed tomography.

PURPOSE: The aim of the authors in this study was to critically evaluate the role of whole-body positron emission tomographic (PET) imaging with fluorine-18 fluorodeoxyglucose (FDG) in staging esophageal cancer, and further to compare this method with conventional imaging with computed tomography (CT). MATERIALS AND METHODS: The authors performed independent, blinded retrospective evaluations of FDG PET images obtained in 47 patients referred for the initial staging of esophageal cancer before minimally invasive surgical staging. Twenty PET studies from patients with nonesophageal thoracic cancers were randomly selected for inclusion in the PET readings. In a subset of 37 of 47 cases, the PET findings were compared with independent readings of CT studies acquired within the same 6-week interval. The utility of the imaging findings was evaluated using a high-sensitivity interpretation (i.e., assigning equivocal findings as positive) and a low-sensitivity interpretation (i.e., assigning equivocal findings as negative). RESULTS: PET was less sensitive (41% in high-sensitivity mode, 35% in low-sensitivity mode) than CT (63% to 87%) for diagnosing tumor involvement in locoregional lymph nodes, which was identified by surgical assessment in 72% of patients. Notable, however, was the greater specificity of PET-determined nodal sites (to approximately 90%) compared with CT (14% to 43%). In detecting histologically proved distant metastases (n = 10), PET performed considerably better when applied in the high-sensitivity mode, with a sensitivity rate of approximately 70% and a specificity rate of more than 90% in the total group and in the subset of patients with correlative CT data. In the low-sensitivity mode, CT identified only two of seven metastatic sites, whereas the high-sensitivity mode resulted in an unacceptably high rate of false-positive readings (positive predictive value, 29%). PET correctly identified one additional site of metastasis that was not detected by CT. CONCLUSIONS: The relatively low sensitivity of PET for identifying locoregional lesions precludes its replacement of conventional CT staging. However, the primary advantage of PET imaging is its superior specificity for tumor detection and improved diagnostic value for distant metastatic sites, features that may substantially affect patient management decisions. In conclusion, PET imaging is useful in the initial staging of esophageal cancer and provides additional and complementary information to that obtained by CT imaging.

Image analysis in patients with cancer studied with a combined PET and CT scanner.

PURPOSE: To compare combined whole-body PET and CT images of different cancers with PET images alone. MATERIALS AND METHODS: Thirty-two patients with known or possible cancers were examined using a combined positron emission tomographic (PET) and computed tomographic (CT) scanner. All data were acquired using this same combined scanner. After an injection of F-18 fluorodeoxyglucose (FDG), noncontrast helical CT imaging of the neck, chest, abdomen, or pelvis was performed. The spiral CT was followed by a PET scan covering the same axial extent as the CT. RESULTS: Coregistered PET-CT images identified and localized 55 lesions. In 10 patients (31%), areas with variable amounts of normal physiologic FDG uptake were distinguished from potential uptake of FDG in a nearby neoplastic lesion. Improved localization was achieved in 9 patients (for a total of 13 lesions, or 24%). CONCLUSION: Combined PET-CT images appear more effective than PET images alone to localize precisely neoplastic lesions and to distinguish normal variants from juxtaposed neoplastic lesions.

Combined PET/CT Imaging in Oncology. Impact on Patient Management.

Purpose: In this work, we describe five oncology patients whose clinical management were uniquely benefited by a novel scanner that acquires positron emission tomography (PET) and x-ray computed tomography (CT) in the same imaging session.Procedures: Co-registered 2-[F(18)]-fluoro-2-deoxy-D-glucose (FDG)-PET and CT images were acquired using a combined PET/CT scanner. Pathology and clinical follow-up data were used to confirm PET/CT scan results.Results: The combined PET/CT scanner demonstrated the ability to distinguish malignant lesions from normal physiologic FDG uptake in the striated muscles of the head and neck as well as excretory and bowel activity in the abdomen and pelvis. Additionally, the technology positively affected patient management through localization for surgical and radiation therapy planning as well as assessment of tumor response.Conclusion: Our experience indicates that simultaneous acquisition of co-registered PET and CT images enabled physicians to more precisely discriminate between physiologic and malignant FDG uptake and more accurately localize lesions, improving the value of diagnostic PET in oncologic applications.

Superphysiologic FDG Uptake in the Non-Paralyzed Vocal Cord. Resolution of a False-Positive PET Result with Combined PET-CT Imaging.

The application of positron emission tomography imaging with 18F-fluorodeoxyglucose (FDG) to the extracranial head and neck has been proven to be effective in the detection and staging of malignancy. The FDG uptake of normal laryngeal tissue is symmetric and low, while benign lesions typically have only slight increases in FDG uptake. We report a case of asymmetric, superphysiologic FDG uptake in the contralateral vocal cord of a patient with a unilateral vocal cord paralysis secondary to sacrifice of the recurrent laryngeal nerve during pneumonectomy for lung cancer. The FDG uptake of the non-paralyzed vocal cord was increased multiple-fold, placing it well within the range of malignancy. Use of unique, combined PET-CT imaging localized the high FDG uptake to the non-paralyzed vocal cord, and laryngoscopy confirmed no evidence of malignancy in the vocal cord. This case demonstrates that a benign cause of false-positive FDG-PET imaging may be encountered during evaluation of the extracranial head and neck for malignancy. We aim to alert the reader to this potential pitfall in the interpretation of FDG-PET imaging, which can be resolved with the use of combined PET-CT imaging and clinical correlation.

Survival of patients with high grade glioma treated with intrathecal thiotriethylenephosphoramide for ependymal or leptomeningeal gliomatosis.

BACKGROUND: The diagnosis of leptomeningeal dissemination of malignant glioma (meningeal gliomatosis) is associated with poor survival. Intrathecal (IT) chemotherapeutic agents used to achieve tumor control and improve survival include methotrexate, cytosine arabinoside (ara-C), thiotriethylenephosphoramide (thio-TEPA), neocarzinostatin, and 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitros ourea hydrochloride (ACNU). Little information exists about survival following administration of IT chemotherapy. The authors report survival data from a series of patients with supratentorial anaplastic astrocytoma (AA) or glioblastoma multiforme (GBM) treated for ependymal or leptomeningeal gliomatosis with IT thio-TEPA. METHODS: The authors reviewed the records of 14 patients treated between 1991 and 1997 (GBM: n = 9; AA: n = 5). All patients were diagnosed with ependymal (n = 8) or leptomeningeal (n = 6) dissemination of tumor on the basis of clinical signs and symptoms, ependymal or leptomeningeal contrast enhancement on magnetic resonance imaging (MRI), and/or cerebrospinal fluid analysis. All 14 patients underwent placement of a ventricular reservoir system and subsequent instillation of IT thio-TEPA on a weekly basis for 6-12 weeks. Response to treatment was evaluated clinically and by MRI at intervals of 1-3 months and 3-6 months from the initiation of IT thio-TEPA. Data on survival from the time of diagnosis of dissemination was assessed. RESULTS: The median survival, from the time of diagnosis of ependymal or leptomeningeal dissemination, of patients who received IT thio-TEPA was 10 months (AA = 19 months; GBM = 10 months). Five of 14 patients had a radiographic response to treatment within 6 months. The median survival of patients with a radiographic response was 15.5 months, compared with 10 months for nonresponders. No significant neurotoxicity or myelopathy was observed. CONCLUSIONS: Early treatment with IT thio-TEPA may result in improved survival with minimal morbidity. Radiographic response may predict prolonged survival.

Evaluation of distant metastases in esophageal cancer: 100 consecutive positron emission tomography scans.

BACKGROUND: Pilot studies suggest positron emission tomography (PET) scanning may be superior to conventional imaging in staging esophageal cancer, especially in the detection of radiographically occult distant metastases. This report summarizes our experience with PET in staging esophageal cancer. METHODS: One hundred consecutive PET scans in 91 patients with esophageal cancer referred for surgery were prospectively collected (1995 to 1998) and compared with computerized tomography (CT) and bone scan. PET images were acquired after injection of 18F-fluorodeoxyglucose and evaluated for abnormal uptake. Minimally invasive surgical staging (MIS) and/or clinical correlation were used to confirm or refute imaging results. RESULTS: MIS or clinical correlation confirmed 70 distant metastases in 39 cases. PET detected 51 metastases in 27 of 39 cases (69% sensitivity, 93.4% specificity, 84% accuracy) compared with CT, which detected 26 metastases in 18 of 39 cases (46.1% sensitivity, 73.8% specificity, 63% accuracy) (p < 0.01). CONCLUSIONS: PET was more accurate than CT in detecting distant metastases, but was only 69% sensitive compared with minimally invasive staging.

Brain tumor volume measurement: comparison of manual and semiautomated methods.

PURPOSE: To compare the reliability of two approaches to measuring enhancing brain tumor volumes--the conventional manual trace method and a threshold-based, semiautomated computer software method. MATERIALS AND METHODS: Two operators rated contrast material-enhanced, T1-weighted axial magnetic resonance (MR) image data sets from 16 patients aged 21-71 years with high-grade gliomas. Each MR data set was rated twice by using manual tracing and twice by using the semiautomated method. The semiautomated measurement method involved a thresholding algorithm based on mixture modeling. The data collection time for each method was recorded. Reliability was measured by using inter- and intraoperator agreement indexes. RESULTS: Mean intraoperator agreement indexes (+/- SD) were 0.90 +/- 0.09 (operator 1) and 0.83 +/- 0.15 (operator 2) for the manual trace method and 0.83 +/- 0.17 (operator 1) and 0.84 +/- 0.16 (operator 2) for the semiautomated measurement method. The mean interoperator agreement was 0.85 +/- 0.14 for the manual method and 0.82 +/- 0.18 for the semiautomated method. The semiautomated method was faster than the manual trace method by an average of 4.6 minutes per patient. CONCLUSION: The semiautomated computer method of measuring tumor volume was faster than the manual trace method. Semiautomated computer approaches offer an alternative to manual tracing for measuring serial tumor volumes in patients with high-grade brain neoplasms.

MR imaging response of brain metastases after gamma knife stereotactic radiosurgery.

PURPOSE: To characterize the magnetic resonance (MR) imaging response of brain metastases after gamma knife stereotactic radiosurgery and determine whether imaging features and tumor response rates correlate with local tumor control and survival. MATERIALS AND METHODS: Serial MR examinations were performed in 48 patients (25 men, 23 women; mean age, 58 years) with 78 lesions. Pretreatment and follow-up enhancing lesion volumes and imaging features were assessed. Rates of response to stereotactic radiosurgery were calculated. Prognostic imaging features affecting local control and survival were analyzed. RESULTS: Local tumor control was achieved in 66 (90%) of 73 metastases at 20 weeks after stereotactic radiosurgery; 61% maintained local control at 2 years. A homogeneous baseline enhancement pattern and initial good response rate (> 50% lesion volume reduction) predicted local control. Five metastases demonstrated a transient volume increase after treatment. The median survival time after stereotactic radiosurgery was 53 weeks and correlated with systemic disease burden and primary tumor type. CONCLUSION: Baseline homogeneous tumor enhancement and initial good response correlate with local control. Initial lesion growth does not preclude local control and may represent radiation-related change. Recognition of these serial MR imaging findings may guide image interpretation and influence treatment in patients with stereotactic radiosurgery-treated metastases.

FDG imaging of spinal cord primitive neuroectodermal tumor.

PET with 18F-fluoro-2-deoxy-glucose (FDG) is well established as an effective imaging modality for evaluating suspected brain tumor recurrence. Use of FDG PET imaging for spinal cord neoplasms has not yet been studied, in large part due to limitations of spatial resolution. One report of FDG PET imaging of brain involvement with primitive neuroectodermal tumor (PNET) demonstrated mild hypometabolism relative to cortical gray matter. We demonstrate with FDG PET imaging the appearance of recurrent intramedullary PNET affecting the cervical spinal cord.

Fluorine-18-fluorodeoxyglucose uptake in pneumonia.

Whole-body PET imaging with 18F-fluorodeoxyglucose (FDG) has been shown to be effective in distinguishing benign and malignant pulmonary disease. Mild elevations in FDG uptake with standardized uptake values (SUVs) less than 2.5 have been reported in benign lesions, including pneumonia. We report a case of presumed bacterial pneumonia with markedly elevated FDG uptake in a patient with a concomitant squamous cell carcinoma in the contralateral lung. SUV's were similar for both lesions (4.9 and 5.4). This case demonstrates an inflammatory etiology for false-positive FDG PET imaging in the evaluation of focal pulmonary abnormalities.

Cerebral MR imaging in intravascular lymphomatosis.

MR imaging data were reviewed retrospectively in four male patients (32 to 74 years old) with histologically confirmed intravascular lymphomatosis (IVL), a rare, aggressive form of non-Hodgkin lymphoma. MR findings included infarct-like lesions (n = 2), focal parenchymal enhancement (n = 3), dural/arachnoid enhancement (n = 2), and, in one case, nonspecific, patchy foci of increased signal in the white matter on long-TR images. All patients had multifocal lesions. Knowledge of the spectrum of MR imaging features in this unusual disorder may aid in diagnosis and potentially enhance the role of imaging in following response to therapy.

Role of positron emission tomography in staging esophageal cancer.

BACKGROUND: Conventional noninvasive staging of esophageal cancer is inaccurate. This study investigated the role of positron emission tomography (PET) in staging esophageal cancer. METHODS: Patients with potentially resectable esophageal cancer were included. A whole-body PET scan was acquired after injection of 18F-fluorodeoxyglucose and was evaluated for areas of increased focal uptake. Accuracy was determined by comparing PET with surgical staging. RESULTS: Potentially resectable esophageal cancer was identified in 35 patients. Positron emission tomography detected nine sites of distant metastases missed by conventional scanning, but one false-negative PET scan occurred in a patient with a 2-mm liver lesion. There were 11 false-negative PET scans for small, intracapsular local-regional nodal metastases (mean diameter 5.2 mm; range 2 to 10 mm). For distant metastases, the sensitivity was 88%, the specificity was 93%, and the accuracy was 91%. For local-regional nodal metastases, the sensitivity was 45%, the specificity was 100%, and the accuracy was 48%. CONCLUSIONS: Positron emission tomography improved our ability to detect distant metastases missed by conventional noninvasive staging of esophageal cancer. Small local-regional nodal metastases are not identified by current PET technology. Early use of PET in the staging of patients with esophageal cancer could facilitate treatment planning and identifying unsuspected distant metastases in up to 20% of patients with a negative metastatic survey by conventional staging.

Mirror-image optic nerve dysplasia with associated anisometropia in identical twins.

BACKGROUND: Monozygotic (MZ) or "identical" twins arise from a single fertilized egg, which divides into two embryos at an early stage of development. As a result, MZ twins have identical genomes and are always of the same sex. METHODS: A case of optic nerve hypoplasia and anisometropia, in association with mirror-image presentation in a set of 12-year-old identical twins, is reported. The monozygotic twinning event responsible for identical twins--as well as the rare phenomenon of mirror imaging--is described. RESULTS: The combined occurrence of anisometropia and optic nerve hypoplasia in mirror-image presentation in a set of monozygotic twins provides a unique opportunity to study the genetic versus environmental influences on the development of optic nerve hypoplasia. CONCLUSIONS: Although the cause of optic nerve hypoplasia remains unclear, its associated mirror-image presentation in this case suggests a possible genetic predisposition.