Imaging of Anaplastic Thyroid Carcinoma.

Anaplastic thyroid carcinoma is fatal if unresectable. However, improved survival has been reported after gross total resection and multimodality therapy. In this report, we describe the contrast-enhanced high-resolution CT characteristics of anaplastic thyroid carcinoma in 57 patients. Anaplastic thyroid carcinoma presented as a large neck mass with necrosis in 82% of cases. The tumors demonstrated common extrathyroidal extension (91%). Sixty-two percent of tumors demonstrated calcification. Visceral space invasion involved the esophagus (62%), trachea (57%), and larynx (29%). Carotid artery encasement was present in 42%, and 43% involved the internal jugular vein. Sixty-three percent had lateral compartment lymphadenopathy; 58% of these nodes were necrotic, and 11% were cystic. No metastatic nodes had calcification. Central compartment lymphadenopathy was seen in 56% of cases, and lateral retropharyngeal lymphadenopathy was detected in 12%. Knowledge of these imaging features aids in guiding the approach to the initial tissue diagnosis with either fine-needle aspiration or core biopsy, assessing the feasibility of surgical resection, and determining prognosis.

mild(®) Lumbar Decompression for the Treatment of Lumbar Spinal Stenosis.

More than 1.2 million people are undergoing treatment for lumbar spinal stenosis (LSS) in the United States. Yet, therapeutic options for these patients are limited to either conservative treatments or highly invasive surgeries. A new image-guided interlaminar decompression procedure, mild(®), offers significant relief for many of these patients by debulking dorsal element hypertrophy while preserving structural stability. mild can be performed without general anesthesia and offers a short recovery period. A meta-analysis of four clinical patient series from multiple institutions in the United States evaluated over 250 patients for safety and clinical efficacy of the mild procedure. Clinical efficacy was evaluated at baseline and at three-month follow-up using validated patient reported outcomes (PRO) instruments including the ten-point Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI). Acute safety and patient outcomes was compared to the Spine Patient Outcomes Research Trial (SPORT). No device or procedure-related serious adverse events (SAEs) have been recorded with the mild procedure. Outcome metrics for patients treated with mild demonstrated statistically significant symptomatic improvement over baseline. When compared to open surgery, mild efficacy results compare favorably, and complication rates are much lower. mild is a safe and effective procedure that decompresses LSS in a minimally invasive manner while preserving the structural stability of the spine.

Capecitabine for 5-fluorouracil-resistant brain metastases from breast cancer.

We report a case in which brain metastases originating from breast cancer responded to treatment with oral capecitabine. The metastases had progressed and Karnofsky performance status deteriorated despite whole brain irradiation, hormonal treatment, and systemic chemotherapy that included 5-fluorouracil (5-FU). In contrast, 2 months of treatment with oral capecitabine produced a partial response, documented by lesion size on magnetic resonance imaging and an improvement in performance status; both measures continued to improve during 11 months of capecitabine treatment.

Performance analysis of a new semiorthogonal spline wavelet compression algorithm for tonal medical images.

Lossy image compression is thought to be a necessity as radiology moves toward a filmless environment. Compression algorithms based on the discrete cosine transform (DCT) are limited due to the infinite support of the cosine basis function. Wavelets, basis functions that have compact or nearly compact support, are mathematically better suited for decorrelating medical image data. A lossy compression algorithm based on semiorthogonal cubic spline wavelets has been implemented and tested on six different image modalities (magnetic resonance, x-ray computed tomography, single photon emission tomography, digital fluoroscopy, computed radiography, and ultrasound). The fidelity of the reconstructed wavelet images was compared to images compressed with a DCT algorithm for compression ratios of up to 40:1. The wavelet algorithm was found to have generally lower average error metrics and higher peak-signal-to-noise ratios than the DCT algorithm.

Pitfalls and artifacts encountered in clinical MR imaging of the spine.

Magnetic resonance (MR) imaging of the spine has become widely accepted as a valuable diagnostic tool. However, there are a number of artifacts and pitfalls associated with spinal MR imaging. Chemical shift artifacts may be induced by bone marrow, epidural fat, or intradural fat. Motion artifacts arise from several sources, which include respiration, flow of fluids, and swallowing. Artifacts due to a nonuniform magnetic field are particularly noticeable within trabecular bone or at bone-soft tissue interfaces but may also be caused by incomplete fat saturation or the presence of metal near the spine. Protocol errors may cause artifacts such as saturation, phase wraparound, truncation, radio-frequency interference, shading, and partial volume averaging. Use of fat saturation, use of motion and flow compensation, and careful screening of patients for metal in clothing can help reduce the occurrence of artifacts. In addition, use of an optimal imaging technique is essential and should include use of the proper surface coil, field of view, and pulse sequence.

Correlation between dynamic MRI and outcome in patients with malignant gliomas.

We assessed the correlation between dynamic MRI results and clinical outcomes in patients with malignant gliomas. Rapid serial MRIs were obtained after bolus injection of gadolinium that resulted in an initial fast uptake followed by a slow uptake of contrast. The maximum rate of uptake and delayed rate of uptake were correlated with survival and prognostic covariates such as age and histology. In 121 subjects, higher maximum uptake rates, 3.6 signal intensity units per second or greater, were associated with shorter survival (p = 0.0066). The correlation of delayed rate of uptake with survival was less significant. After adjusting for age, histology, and Karnofsky performance score, the maximum rate of uptake remained more significantly correlated with survival than the delayed rate of uptake. Thirty-one patients had surgery within 1 month of dynamic MRI, and those with glioblastoma multiforme or anaplastic gliomas had higher maximum rates of uptake than those with pure necrosis or mixed tumor and necrosis (p = 0.022). No correlation between delayed rate of uptake and histology was seen in this group of patients. Our results suggest that the maximum rate of uptake in dynamic MRI can be a prognostic measure for patients with malignant gliomas. Further prospective study is needed to assess the utility of this technique for evaluating brain tumors.

The significance of lack of MR contrast enhancement of supratentorial brain tumors in adults: histopathological evaluation of a series.

BACKGROUND: To correlate magnetic resonance imaging (MRI) findings of non-enhancement of supratentorial brain neoplasms in adults with histopathologic findings. METHODS: Forty adult patients whose preoperative MRI studies demonstrated a non-enhancing supratentorial brain neoplasm were identified retrospectively. Biopsy material for all patients was then reviewed by a board-certified neuropathologist. RESULTS: Histopathologic examination identified 24 (60%) low-grade gliomas: 4 (10%) low-grade astrocytomas, 10 (25%) low-grade gliomas (not further classified), 8 (20%) low-grade oligodendrogliomas, and 2 (5%) low-grade mixed oligoastrocytomas. However, 16 (40%) nonenhancing lesions were classified as anaplastic gliomas: 12 (30%) anaplastic astrocytomas, 1 (2.5%) anaplastic mixed oligoastrocytoma, 1 (2.5%) anaplastic oligodendroglioma, and 2 (5%) anaplastic infiltrating gliomas of indeterminate subtype. CONCLUSION: Non-enhancement of supratentorial brain neoplasms in adults does not equate with low-grade malignancy. This fact should be taken into account when biopsy and treatment are being planned in patients with nonenhancing brain tumors. More aggressive and/or surgical therapy might be indicated for such lesions, particularly those in the nondominant hemisphere or nonmotor areas.

Introduction to wavelet-based compression of medical images.

Medical image compression can significantly enhance the performance of picture archiving and communication systems and may be considered an enabling technology for telemedicine. The wavelet transform is a powerful mathematical tool with many unique qualities that are useful for image compression and processing applications. Although wavelet concepts can be traced back to 1910, the mathematics of wavelets have only recently been formalized. By exploiting spatial and spectral information redundancy in images, wavelet-based methods offer significantly better results for compressing medical images than do compression algorithms based on Fourier methods, such as the discrete cosine transform used by the Joint Photographic Experts Group. Furthermore, wavelet-based compression does not suffer from blocking artifacts, and the restored image quality is generally superior at higher compression rates.

Dynamic imaging of intracranial lesions using fast spin-echo imaging: differentiation of brain tumors and treatment effects.

The purpose of this study was to develop a technique for differentiating between recurrent brain tumors and treatment-related changes, such as radiation necrosis, using dynamic MRI. Ninety-five patients with intracranial mass lesions were evaluated using T1-weighted fast spin-echo (FSE) MRI at 1.5 T. Pathologies included treatment-related changes (n = 32), primary tumors (n = 41), metastatic tumors (n = 5), meningiomas (n = 4), and mixed primary/treatment related changes (n = 13). Signal enhancement-time curves were analyzed by fitting to a sigmoidal-exponential function. Maximal enhancement rates were calculated as the first derivative of the fitted curve. Based on the maximal enhancement rates, treatment-related changes could be differentiated from primary tumors, metastatic tumors, and meningiomas at the P < .05 confidence level. Lesions of mixed tumor and treatment-related change had intermediate values. Dynamic MRI can be used to differentiate treatment-related changes from primary tumors in previously treated patient populations based on maximal enhancement rates. Individual case studies demonstrate the clinical significance of these findings.

A digital imaging and communications in medicine (DICOM) print service for chest imaging.

Large-scale picture archiving and communication systems (PACS) have not been widely implemented in this or other countries. In almost all radiology departments film remains the medium for diagnostic interpretation and image archive. Chest imaging is the dominant screening examination performed within most imaging departments and as such, is an extremely high-volume, low-margin examination. Digital technologies are being applied to chest imaging to overcome limitations of screen-film receptors (limited latitude) and current film management systems (single-image copy). Efficient management of images and information is essential to the success of a chest imaging program. In this article we report on a digital imaging and communications in medicine (DICOM)-based centralized printing network for chest imaging. The system components and their operational characteristics are described. Our experience integrating DICOM-compliant equipment supplied by several vendors is described. We conclude that the print model supported by DICOM is adequate for cross-sectional (eg, computed tomography and magnetic resonance) imaging but is too simplistic to be generally applied to projection radiography.

A review of MRI pulse sequences and techniques in neuroimaging.

BACKGROUND: The unmatched soft tissue contrast provided by magnetic resonance imaging (MRI) has made it the modality of choice for many neuroimaging examinations. The fact that signal intensity in MRI depends on many parameters, including spin-lattice and spin-spin relaxation times, proton density, and velocity, makes it possible to highlight various pathologies by appropriate choice of pulse sequences and pulse sequence parameters. It is somewhat overwhelming however, to filter through various pulse sequences and parameters in order to understand how their selection affects image contrast. This brief review is intended to highlight common pulse sequences and parameters as well as introduce new techniques currently being released for clinical use. MATERIALS: Basic pulse sequences are described and the influence of the acquisition parameters on image contrast are illustrated. Such basic sequences include the ubiquitous spin echo, fast spin echo, and gradient echo sequences. Specialized techniques for fat suppression and magnetic resonance angiography are also presented. Currently approved contrast agents for use in MRI are briefly reviewed, and various advanced pulse sequences, such as those for diffusion and magnetization transfer contrast imaging, are briefly outlined. RESULTS: The utility of basic and advanced pulse sequences are demonstrated by clinical examples and images of normal brain and spine. New sequences and techniques are briefly outlined with regard to their potential for improving neuroimaging examinations. CONCLUSIONS: This brief review outlines how the choice of pulse sequence and acquisition parameters influences the resulting image contrast for a variety of basic and advanced imaging techniques.

Remission of refractory gestational trophoblastic disease in the brain with ifosfamide, carboplatin, and etoposide (ICE): first report and review of literature.

Gestational trophoblastic disease (GTD) metastatic to the brain has a very poor prognosis with a survival rate of less than 25%, especially for patients in whom brain metastases develop while on or after chemotherapy. Cure can be achieved by chemotherapy alone. The regimen of etoposide, methotrexate, actinomycin-D, vincristine, and cyclophosphamide has shown encouraging results and is considered to be standard first-line treatment for high risk patients. For patients in whom this regimen fails, a salvage chemotherapy regimen is used. The combination of ifosfamide, carboplatin, and etoposide (ICE) has synergistic activity in preclinical studies. This regimen has shown activity in metastatic breast cancer and non-small-cell lung cancer as well as platinum-resistant germ-cell tumors and metastatic GTD. This is the first report of a patient with a highly refractory GTD in whom brain metastasis developed while on chemotherapy, and whose brain metastasis went into remission with a low dose ICE regimen. Accordingly, ICE may be considered for patients with chemotherapy refractory GTD metastatic to the brain.

Use of intraoperative ultrasound for localizing tumors and determining the extent of resection: a comparative study with magnetic resonance imaging.

A prospective study of 70 patients with intraparenchymal brain lesions (36 gliomas and 34 metastases) was performed to evaluate the efficacy of intraoperative ultrasound (IOUS) in localizing and defining the borders of tumors and in assessing the extent of their resection. Eighteen of the 36 glioma patients had no previous therapy. All of these 18 tumors were well localized by IOUS; margins were well defined in 15 and moderately defined in three. The extent of resection was well defined on IOUS in all 18 patients, as confirmed by measurements taken on postoperative magnetic resonance (MR) images (p = 0.90). The remaining 18 patients with gliomas had undergone previous surgery and/or radiation therapy; five had recurrent tumors and 13 had radiation-induced changes. The extent of resection of the recurrent tumors was well defined in all but one patient, as confirmed by postoperative MR imaging. The extent of resection was poorly defined in all 13 patients whose pathology showed radiation effects. All 34 metastatic lesions were well localized and had well-defined margins. In addition, IOUS accurately determined the extent of resection in all cases, the results were confirmed with postoperative MR imaging. In conclusion, IOUS is not only helpful in localizing and defining the margins of gliomas and metastatic brain lesions, it also accurately determines the extent of resection, as confirmed by postoperative MR imaging. This assessment does not apply, however when the lesion is due primarily to radiation effect.

Imaging studies of cerebral hyperperfusion after carotid endarterectomy. Case report.

A case is reported of severe unilateral hemispheric edema and localized hemorrhage associated with seizures following endarterectomy of an ipsilateral high-grade carotid stenosis. Imaging studies including angiography, computerized tomography (CT), magnetic resonance imaging/angiography, and xenon-CT, suggested postoperative ipsilateral cerebral hyperperfusion. Cerebral hyperperfusion syndromes caused by a probable failure of vascular autoregulation are rare but potentially serious complications after endarterectomy. The literature on this type of complication is briefly reviewed, and the role of various imaging modalities in identification of the syndrome and in guiding management decisions is emphasized.

MR imaging of head and neck tumors: comparison of T1-weighted contrast-enhanced fat-suppressed images with conventional T2-weighted and fast spin-echo T2-weighted images.

OBJECTIVE: The purpose of this study was to determine the value of three MR pulse sequences for the detection of tumors and abnormal lymph nodes in the head and neck. This was accomplished by quantifying differences in contrast between tumor, lymph node, and respective adjacent tissue on contrast-enhanced fat-suppressed T1-weighted MR images, conventional spin-echo T2-weighted images, and fast spin-echo fat-suppressed T2-weighted images in a group of patients with head and neck tumors. SUBJECTS AND METHODS: Two groups of patients with head and neck tumors were studied. In the first group (16 patients), contrast-enhanced fat-suppressed T1-weighted images were compared with conventional spin-echo T2-weighted images. In the second group (21 patients), contrast-enhanced fat-suppressed T1-weighted images were compared with fast spin-echo fat-suppressed T2-weighted images. The detectability of tumor and abnormal lymph nodes was measured by calculating the contrast-to-noise ratio. RESULTS: The fat-suppressed T1-weighted images had significantly higher (p < or = .02) contrast-to-noise ratios for both the primary tumor and lymph nodes than either conventional or fast spin-echo T2-weighted images did. However, subjective evaluation of the contrast-to-noise ratios proved satisfactory for tumor detection with all three imaging sequences (contrast-enhanced fat-suppressed T1-weighted, fast spin-echo fat-suppressed T2-weighted, and conventional T2-weighted). CONCLUSION: Our results show that fat-suppressed contrast-enhanced T1-weighted images provide the highest contrast-to-noise ratio for head and neck tumors and abnormal lymph nodes. However, head and neck tumors encompass a broad range of neoplasms that are distributed in a complicated anatomic area. Therefore, in some patients, a combination of contrast-enhanced fat-suppressed T1- and T2-weighted images, preferably fast spin-echo fat-suppressed images, is useful for detection of these tumors and nodal metastases.

The anatomy of the posterior communicating artery as a risk factor for ischemic cerebral infarction.

BACKGROUND: After the occlusion of an internal carotid artery the principal source of collateral flow is through the arteries of the circle of Willis, but the size and patency of these arteries are quite variable. Study of the anatomy of the collateral pathways in patients with internal-carotid-artery occlusion with or without infarction in the watershed area of the deep white matter may identify patterns that afford protection from ischemic infarction. METHODS: Using conventional magnetic resonance imaging and three-dimensional phase-contrast magnetic resonance angiography, we evaluated 29 consecutive patients (32 hemispheres at risk) with angiographically proved occlusion of the internal carotid artery. Four collateral pathways to the occluded vessel were evaluated: the proximal segment of the anterior cerebral artery, the posterior communicating artery, the ophthalmic artery, and leptomeningeal collateral vessels from the posterior cerebral artery. RESULTS: Only features of the ipsilateral posterior communicating artery were related to the risk of watershed infarction. The presence of posterior communicating arteries measuring at least 1 mm in diameter was associated with the absence of watershed infarction (13 hemispheres, no infarcts; P < 0.001). Conversely, there were 4 watershed infarcts in the 6 hemispheres with posterior communicating arteries measuring less than 1 mm in diameter and 10 infarcts in the 13 hemispheres with no detectable flow in the ipsilateral posterior communicating artery. CONCLUSIONS: A small (< 1 mm in diameter) or absent ipsilateral posterior communicating artery is a risk factor for ischemic cerebral infarction in patients with internal-carotid-artery occlusion.

Simple adaptations to extend the range of flow cytometry five orders of magnitude for the DNA analysis of uni-and multicellular systems.

Procedures and instrumentation are described to extend the capability of a cytometry system to record samples that exhibit a wide range of fluorescence such as multicellular systems. The method employs a log amplifier in combination with a set of neutral density filters that reduces the incident light reaching the photomultiplier tube. With any given filter, signals within an intensity range of 200-fold can be measured; different filters can be used to obtain an extended overall range. Polystyrene fluorescent microspheres and a variety of mithramycin stained biological samples ranging from yeast cells to Paramecium were processed by the system. The relative DNA content of individual multicellular embryos was determined for a heterogeneous population of embryonic stages isolated from the nematode, Caenorhabditis elegans. As part of the evaluation of the procedure, the practical upper limit of range extension was determined. The most intense fluorescent signal was produced when untreated pecan pollen stained with ethidium bromide fluoresced with a factor (8.4 +/- 1.3) X 10(4) more than ethidium bromide stained E. coli cells.