Search

Objectives: Laser-induced thermal therapy (LITT) for cancer is a technique whereby a source of energy (laser, radiofrequency, ultrasonic, cryoenergy, and so on) is directly applied into a tumor at various depths. Recent studies have demonstrated the efficiency of ultrasound (UTZ) and magnetic resonance imaging (MRI) for real- or "near" real-time tumor and vessel identification as well as monitoring and quantifying energy-induced tissue damage. The objective of this study is to report UCLA's experience using UTZ monitoring of Nd:YAG laser thermal ablation of malignant cervical adenopathy in a phase II study. Study Design: The authors conducted a retrospective study of patients treated at a tertiary medical center. Methods: Forty-seven patients with a total of 55 neck tumors were treated on an outpatient basis in the operating room using UTZ for image-guided laser interstitial thermal therapy. Laser energy was delivered through an SLT Nd:YAG laser powered at 30 W (power density: 2,200 J/cm). Results: Eleven patients had a complete response ranging from 5.5 to 90 months (mean, 22.1 months). Based on the findings of this study, it was possible to show that proximity to the carotid artery was the most relevant factor in projecting patient survival. Patients' individual treatment analysis and final outcome are further discussed. Conclusions: LITT ablation of malignant cervical adenopathy was considered safe and feasible. No intraoperative complications occurred. Further development of this technique applying laser energy delivery to mathematical imaging models should lead to more effective tumor palliation as an alternative to surgery. [ABSTRACT FROM AUTHOR]

Objective: The retropharyngeal space is a deep neck space susceptible to a host of disease processes. Surgical access to this space is technically difficult and associated with potential morbidity. An image-guided fine-needle aspiration (FNA) biopsy, if proven accurate and safe, would be of great benefit as an alternative diagnostic approach to this space. This study reports on the use of magnetic resonance imaging (MRI)--guided FNA for diagnostic evaluation of retropharyngeal lesions. Technical details of needle systems, approach to this space, and reliability of this method are described.Study Design: This is a prospective study of 14 patients with retropharyngeal lesions who underwent MRI-guided FNA biopsy at the University of California at Los Angeles Center for the Health Sciences between October 1989 and October 1998.Methods: A 0.2-tesla open magnet was used to obtain magnetic resonance images of each retropharyngeal lesion. After standard skin preparation a coaxial needle system was used to reach and sample the lesion. In most instances, the specimen was immediately stained and examined by a cytopathologist for adequacy before removing the patient from the scanner.Results: Eleven of 14 (78%) patients had diagnostic aspirations; only 2 of these 11 patients required additional surgical biopsy for more specific histological characterization of their lesions before definitive treatment recommendations were given. All aspiration procedures were well tolerated and without any complications.Conclusion: We have demonstrated that MRI-guided approach to the retropharynx is feasible, safe, and sensitive enough to obviate the need for open biopsies in a large percentage of patients. [ABSTRACT FROM AUTHOR]

Positron emission tomography (PET) has recently proved to be highly sensitive in detecting known extracranial head and neck squamous cell carcinomas when compared to computed tomography and magnetic resonance imaging (MRI). The ability of PET to detect early subclinical recurrent squamous cell malignancies in patients who received primary radiotherapy was evaluated. A new PET-MRI coregistration technique was used to determine precise anatomic tumor location, enabling directed biopsies to confirm the presence of malignancy, and to plan additional therapeutic strategies. Ten patients underwent PET evaluation with intravenous [18F]-fluorodeoxyglucose and received postradiotherapy MRI scans. In all cases, PET accurately detected the presence of recurrent disease despite negative or equivocal MRI scans and indeterminate clinical examinations. PET appears to be highly effective in detecting early recurrent head and neck squamous cell malignancies in postirradiated patients. [ABSTRACT FROM AUTHOR]

This report presents a 55-year-old woman who underwent 2 Teflon injections in 1971 for a patulous eustachian tube. The patient returned in 2006 with a bloody left otorrhea. A positron-emission tomography-CT scan demonstrated a 2-cm hypermetabolic parapharyngeal mass, initially interpreted as a skull base tumor. Repeat neck CT confirmed a 2-cm hyperattenuated left parapharyngeal granulomatous mass. This is the first reported case of a Teflon granuloma presenting as a false-positive parapharyngeal mass.

Background: (18)F-FDG PET has a high accuracy for re-staging of head and neck cancer. The purpose of this study was to determine whether the diagnostic accuracy can be further improved with integrated PET/CT., Materials and Methods: Forty-nine patients with a mean age of 59+/-18 years were studied retrospectively. Histo-pathological verification was available either from complete tumor resection with or without lymph node dissection (n=27) or direct endoscopic biopsy (n=16) or ultrasound guided biopsy (n=6). Two reviewers blinded to the pathological findings read all PET images in consensus. An experienced radiologist was added for the interpretation of the PET/CT images., Results: Tissue verification was available for 110 lesions in 49 patients. Sixty-seven lesions (61%) were biopsy positive and 43 (39%) were negative for malignant disease. PET and PET/CT showed an overall accuracy for cancer detection of 84 and 88% (p=0.06), respectively. Sensitivity and specificity for PET were 78 and 93% versus 84 (p=NS) and 95% (p=NS) with PET/CT. A patient-by-patient analysis yielded a sensitivity, specificity and accuracy for PET of 80, 56 and 76%, compared to 88% (p=NS), 78% (p=NS) and 86% (p=0.06) for PET/CT., Conclusion: The results of this study indicate that PET/CT does not significantly improve the detection of recurrence of head and neck cancer. However, a trend towards improved accuracy was observed (p=0.06).

Background: MRI-guided procedures have previously been limited by technical difficulties, including the need for MRI-compatible instruments, slow image acquisition time, and the closed nature of conventional MRI scanners. The development of open configuration MRI systems with in-room, contemporaneous imaging has greatly increased the potential for MRI-guided interventional procedures. We evaluate our clinical experience applying this technology to the head and neck., Methods: An open design 0.2T magnet combined with an in-room monitor was used for 24 MRI-guided needle localization procedures in the head and neck. Success of the procedures was based on the ability to accurately position the instrument in the target region to allow biopsy or treatment., Results: In all 24 cases placement of the instrument within the target tissue was successful., Conclusion: MRI-guided needle-localization procedures in an open design magnet with in-room, contemporaneous image monitoring offer advantages over previous conventional interventional MRI systems by allowing interactive guidance with near real-time imaging feedback. As a result, procedure time is reduced and accuracy of instrument positioning is increased., (Copyright 2000 John Wiley & Sons, Inc.)

Focal regions of T1-shortening have been observed in magnetic resonance imaging (MRI)-monitored thermal ablations of perfused tissues. The aims of this study were two-fold: to find evidence for heat-induced conversion of hemoglobin (Hb) to methemoglobin (mHb), and to investigate the effects of heat treatment of in-vitro blood components upon their MR relaxation times. Spectrophotometric studies were performed to confirm the heat-induced formation of methemoglobin. Preparations of whole and fractionated blood, previously submitted to elevated temperatures of 40 degrees C to 80 degrees C, were imaged and the relaxation times were calculated. Optical absorption spectra of samples containing free Hb, heated to 60 degrees C, showed increased light absorption at 630 nm, evident of mHb presence. Short T1 values in whole blood (1.13 s) and packed red blood cell (0.65 s) compartments, heated at 60 degrees C, compared to their baseline values (1.62 s and 0.83 s, respectively), were attributed to mHb formation. In relation to MRI-guided thermal interventions, these results suggest a possible explanation for observation of hyperintense regions on T1-weighted images.

Purpose: Chondromas and chondrosarcomas of the larynx are rare cartilaginous tumors making up less than 1% of all laryngeal tumors. Patients typically present with symptoms of hoarseness, dysphagia, or dyspnea. The most common location in the larynx for these tumors is the cricoid cartilage. Radiographically, these lesions are typically hypodense, well-circumscribed masses containing mottled calcifications with smooth walls centered within the cartilage., Materials and Methods: We present 6 cases of chondroid tumors of the larynx., Results: One patient had a chondroma, 4 patients had low-grade chondrosarcomas, and 1 patient had an intermediate-grade chondrosarcoma. Two partial laryngeal resections and 4 total laryngectomies were performed., Conclusions: In most cases of chondroma or chondrosarcoma of the larynx, conservative surgery should be attempted, but total laryngectomy may be required for large or recurrent lesions.

Frameless MR-guided procedures have had limited application using conventional closed magnets, due largely to the technical difficulties involved. As a result of in-room MR image-monitoring capabilities, new open-design magnets now allow frameless stereotaxis using contemporaneous imaging to guide more invasive procedures. We evaluate our clinical experience with this new technique. An open-design 0.2 T magnet (Siemens OPEN) combined with an in-room monitor was used for 33 frameless MR-guided procedures (aspiration cytology, biopsy, and/or treatment) in a variety of locations in the head, neck, spine, brain, pelvis, and abdomen. Success of the procedure was based on the ability to accurately position the instrument in the target region to allow biopsy and/or treatment. The open-design magnet allowed the physician to directly access the patient for frameless stereotaxis as the procedure was performed. The in-room monitor provided contemporaneous imaging feedback during the procedure for successful placement of the instrument in the target region. Twenty-eight biopsy and five treatment procedures were performed. In all cases the technique resulted in successful placement of the instrument within the target tissue to complete the procedure. MR-guided procedures using contemporaneous imaging frameless stereotaxis are possible in an open-design magnet with in-room image monitoring and offer exciting possibilities for further development.

Purpose: Early experience has shown that positron-emission tomography (PET) is a useful technique for the detection of occult squamous cell carcinoma of the head and neck. Although highly sensitive, PET lacks definition of anatomic detail and therefore does not localize pathology precisely. To circumvent this limitation, a computerized coregistration technique has been developed at the University of California-Los Angeles to correlate PET and magnetic resonance images (MRI). This method allows accurate, precise anatomic localization of areas of heightened glucose metabolism, including subclinical tumors., Materials and Methods: The technique uses a coregistration computer program that precisely superimposes the PET scan with the corresponding MRI image., Results: Two cases are presented in which PET-MRI coregistration was used to anatomically define the areas of heightened glucose metabolism. Large tumors were selected because the precision of the method can be verified., Conclusion: The coregistration technique is a valuable addition to PET imaging, particularly in its ability to anatomically localize PET findings. The most important application of this technique is to facilitate the biopsy of subclinical lesions identified on PET.

Therapeutic outcome of head and neck cancer is influenced strongly by the presence of nodal metastases. Sensitivity and specificity of the physical examination for the diagnosis of nodal metastasis is unsatisfactory, resulting in both false negatives and false positives of 25 to 40%. Preoperative detection of nodal metastases therefore becomes one of the important goals of imaging studies of patients with head and neck cancer. Despite several advanced techniques and the wide clinical use of MR, MR has surprisingly added little to the diagnostic accuracy of contrast-enhanced CT. Although CT and MR allow detection of abnormally enlarged nodes or necrotic nodes, neither borderline-sized nodes without necrosis nor extracapsular spread are reliably differentiated from reactive or normal nodes in patients with head and neck cancer. Lack of definitive diagnostic methods of metastatic lymph nodes is a serious shortcoming in the preoperative workup for patients with head and neck cancer. To avoid missing small metastatic nodes, a large number of patients clinically staged as N0 have undergone elective neck dissection to exclude metastases. With development of more tissue-specific imaging techniques, patients can be better characterized according to the status of nodal disease so that an appropriate therapeutic protocol can be designed for an individual case.

Our objectives were to further characterize an artifact related to the localized failure of the frequency-selective (FATSAT) fat suppression magnetic resonance (MR) imaging technique. We constructed two phantoms simulating human orbital anatomy and imaged them on a 1.5-T MR scanner using (FATSAT) and short T1 inversion recovery (STIR) techniques of fat suppression. The first phantom resembled orbit structural configurations; it was imaged in coronal and axial planes and in varying orientations with respect to the main magnetic field (Z axis) to study the features of the artifact and to reproduce the asymmetry seen in clinical cases. We designed the second phantom to enable quantification of the change in artifact size with change in orientation. We imaged the orbits of a normal human volunteer in similar planes and orientations, and compared the results to clinical cases demonstrating the artifact and true orbital disease. The artifact identified with localized failure of FATSAT fat suppression manifested as regions of hyperintensity maximal at fat-air interfaces, with gradual fading of the increased signal with distance from the interfaces. The artifact was most prominent when the interfaces were perpendicular to the axis of the main magnetic field (Z axis). The regions of increased brightness obscured normal orbital structures but were not associated with alterations in the geometry of these structures. Changes in orientation of the interfaces with respect to the Z axis, both in the phantoms and normal volunteer, reproduced the asymmetry of fat suppression failure seen in clinical cases. The relationship of size of the artifact to change in orientation was non-linear. The artifact was not seen on STIR images. We concluded that failure of FATSAT fat suppression may mimic orbital disease, particularly if asymmetric. As predicted by the Maxwell electromagnetism equation, slight variations in orientation of the fat-air interface to the Z axis may produce large asymmetries in fat suppression failure in the orbit. Confirmation may require either comparison with additional pulse sequences [T1-weighted spin echo (T1W SE) or STIR] or repositioning the patient's head to check for persistence of the finding with varying orientations.

A prototype multimedia medical database is described for supporting thermal ablation therapy of brain tumors. Its design is motivated by the major need to manage and access multimedia information on the progress and reaction of tumors to various therapy protocols. The database links images to patient data in a way that permits the use to view and query medical information using alphanumeric, temporal, and feature-based predicates. Visualization programs permit the user to view or annotate the query results in various ways. These results support the wide variety of data types and presentation methods required by neuroradiologists to manage thermal ablation therapy data. The database satisfactorily meets the requirements defined by thermal ablation therapy. A similar approach is being undertaken for supporting different therapies of other types of tumors, thus showing the generality of our approach.

Interventional MRI is in its early stages of development. Nevertheless, the design of new interventional MRI scanners that allow maximum direct access to the patient combined with the development of new interventional MRI pulse sequences and localization systems, means that the archetypal operating rooms of the 21st century may well contain dedicated interventional MRI units for combined radiological and surgical procedures. The present article looks at the state of interventional MRI today and looks ahead to what may be forthcoming in the not-too-distant future. After briefly discussing the instrumentation necessary for practical interventional MRI, the article will go on to describe a number of different approaches to, and clinical applications for, interventional MRI. The use of MRI in guiding and controlling tumor ablation, aspiration cytology and surgical biopsy of different body parts is described.

Background: Depressed patients have a variety of brain structural alterations, the most common being atrophy and deep white-matter lesions. Alterations in brain function also are common, particularly regional decreases in cerebral metabolism and perfusion., Method: We review here the evidence that alterations in brain structure and function may explain some of the heterogeneity in outcomes of depression. We also report initial results suggesting that measurement of brain structure and function may help to predict outcomes of treatment for depression. Brain structure was examined using three-dimensional reconstruction and volumetric analysis of magnetic resonance imaging (MRI) scans. Brain function was examined using quantitative electroencephalography (QEEG), performed at baseline and serially during the course of treatment. QEEG measures included coherence (a measure of synchronized activity between brain regions) and cordance (a measure strongly associated with regional cerebral perfusion)., Results: Depressed patients have been reported to have larger volumes of white-matter lesions than controls. We have found that some types of white-matter lesions are associated with lower coherence and that subjects with low coherence had significantly poorer outcomes of treatment for depression at 2-year follow-up. Depressed subjects had low cordance at baseline, which decreased further during the course of effective treatment. Subjects who did not improve had little or no change in cordance. Changes in cordance were detected prior to the onset of clinical response, with decreases seen as early as 48 hours after the initiation of treatment in subjects who showed eventual response., Conclusion: These preliminary results suggest that functional imaging using QEEG may be useful for assessing, and possibly predicting, outcomes of treatment for depression.

Purpose: To assess the effect of a capitation reimbursement plan with attendant changes in service arrangements on the utilization of radiologic services, financially on the payer, and on the satisfaction of patients and referring physicians., Materials and Methods: Outpatient radiologic services for a defined population of 20,000 company employees and their dependents were converted from a point-of-service managed care plan to a capitation payment plan. Under the capitation plan, nonemergent outpatient diagnostic imaging was performed at a newly constructed imaging center staffed by general radiologists. All cross-sectional images and certain projectional studies were also over-read (read again after the initial reading by local radiologists) by subspecialists. Utilization data obtained before and after the conversion were analyzed. The financial effect on the employer and the satisfaction of patients and physicians were also assessed., Results: Quality imaging services were provided under the capitation plan with financial savings by the employer. Use was higher for cross-sectional imaging, especially magnetic resonance imaging studies, and was lower for nonmammographic plain radiography. Consumer satisfaction was high., Conclusion: Under certain conditions, conversion to a capitation system for imaging can lead to improved quality of care and decreased overall health-care costs.

A multimedia medical database model and prototype is described for supporting a timeline-based presentation of information. The database links image and text data in a way that permits users to look at medical information in a single unified view. Various visualization programs permit the user to view data in various ways, including full image views, graphs, and tables. Our technology is applied for proof-of-concept to two areas: thoracic oncology and thermal tumor ablation therapy of the brain. This effort is part of the multidisciplinary KMeD project in collaboration with medical research and clinical treatment projects at UCLA.

The use of magnetic resonance imaging to directly guide therapy is a new area of investigation. Clinical magnetic resonance imaging has the potential to evolve from a purely diagnostic tool into a guide for invasive procedures. The idea of using magnetic resonance to guide percutaneous biopsy developed one decade ago. Magnetic resonance-guided fine-needle aspiration for head and neck lesions has become a standard technique some institutions. Once the needle reaches a lesion in the head and neck, it is natural to explore the possibility of treatment in the same setting. The concept of interventional magnetic resonance imaging has generated interest among radiologists, surgeons, and manufacturers. This article provides an overview of interventional procedures of the head and neck and other new imaging techniques that have been developed.

Obstructive lung disease is the most common form of respiratory disturbance. However, the location of brain structures underlying the ventilatory response to resistive expiratory loads is unknown in humans. To study this issue, midsagittal magnetic resonance images were acquired in eight healthy volunteers before and after application of a moderate resistive expiratory load (30 cmH2O/liter/s), using functional magnetic resonance imaging (fMRI) strategies (1.5-T magnetic resonance; repetition time: 72 ms; echo time: 45 ms; flip angle: 30 degrees; field of view: 26 cm; slice thickness: 5 mm; 128 x 256 x 1 number of excitations). Digital image subtractions and region of interest analyses revealed significant increases in fMRI signal intensity in discrete areas of the ventral medulla, ventral and dorsal pontomedullary structures, basal forebrain, and cerebellum. Upon load withdrawal, a rapid fMRI signal off-transient occurred in all activated sites. Application of an identical load immediately after recovery from the initial stimulus resulted in smaller signal increases (P < 0.02). Prolongation of load duration was associated with progressive fMRI signal decrease across activated regions. In three additional subjects, the threshold for significant MRI signal increases was established at expiratory loads > or = 15 cmH2O/liter/s and was dose dependent with increasing loads. We conclude that resistive expiratory loads > or = 15 cmH2O/liter/s elicit regional activation of discrete brain locations in humans.

Rationale and Objectives: Variations in venous deoxyhemoglobin levels in response to neuronal activation represent a complex interplay between focal changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and regional metabolism. The authors present a mathematic model that characterizes the response of venous oxygenation to changes in these variables., Methods: Using a mass balance approach, the equations for a simple input-output model are derived and solved using Matlab. Changes in blood oxygenation are related to available results from functional magnetic resonance imaging experiments., Results: Increases in CBF produce declines in oxygen extraction fraction and venous deoxyhemoglobin according to Fick's law, and are quantitatively in agreement with available magnetic resonance and positron-emission tomography data. A flow-volume envelope defines the changes in CBF relative to CBV., Conclusions: It is possible to obtain a quantitative understanding of changes in blood oxygenation and to relate these changes to the observed dynamics of magnetic resonance signal change in the setting of functional stimulation.

We wished to determine whether the number of central nervous system (CNS) white matter lesions on magnetic resonance imaging (MRI) is increased in patients with nonarteritic ischemic optic neuropathy (NAION). T2-Weighted axial images of the brain in 13 patients with acute NAION and 16 age-matched controls were used to tabulate the number of subcortical and periventricular white matter lesions. Groups were compared by t test for means, the Wilcoxon-Mann-Whitney rank-sum test, and chi-square test for proportions with at least one lesion. The mean number of CNS white matter ischemic lesions in the NAION group was 4.0 (range 0-20) as compared to 1.4 (range 0-7) in the control group. The difference in these samples suggested a significant increase in NAION (p = 0.069, rank-sum test). The proportions of patients with at least one lesion were not significantly different (53.8% NAION vs. 56.3% controls). The data suggest an increased number of CNS white matter lesions in patients with NAION.

Purpose: To determine the natural time course of development of hyperacute thermal lesions in the brain., Materials and Methods: Ten interstitial lesions were created in five rabbit brains with a radio-frequency probe; an electrode-tip temperature of 80 degrees C was maintained for 60 seconds. Continuous fast spin-echo magnetic resonance (MR) imaging was used to follow lesion development for a minimum of 30 minutes. Temporal variations in lesion size and signal intensity were examined. Findings in final images were correlated with histologic findings., Results: Images demonstrated a focal hyperintense zone, which developed into an expanding ring of edema surrounding a necrotic center in about 10 minutes. Quantitative analysis revealed a 23% +/- 6 (standard deviation) increase in average signal intensity of the edema layer and a 152% +/- 41 increase in overall lesion size., Conclusion: Full development of a thermal lesion is delayed for a period of minutes. Clinical implications of this effect should be considered when MR imaging-guided thermal ablation is performed.

Compensatory ventilatory responses to increased inspiratory loading are essential for adequate breathing regulation in a number of pulmonary diseases; however, the human brain sites mediating such responses are unknown. Midsagittal and axial images were acquired in 11 healthy volunteers during unloaded and loaded (30 cmH2O; 1 cmH2O = 98 Pa) inspiratory breathing, by using functional magnetic resonance imaging (fMRI) strategies (1.5-tesla MR; repetition time, 72 msec; echo time, 45 msec; flip angle, 30 degrees; field of view, 26 cm; slice thickness, 5 mm; number of excitations, 1; matrix, 128 x 256). Digital image subtractions and region of interest analyses revealed significantly increased fMRI signal intensity in discrete areas of the ventral and dorsal pons, interpeduncular nucleus, basal forebrain, putamen, and cerebellar regions. Upon load withdrawal, certain regions displayed a rapid fMRI signal off-transient, while in others, a slower fMRI signal decay emerged. Sustained loading elicited slow decreases in fMRI signal across activated regions, while second application of an identical load resulted in smaller signal increases compared to initial signal responses (P < 0.001). A moderate inspiratory load is associated with consistent regional activation of discrete brain locations; certain of these regions have been implicated in mediation of loaded breathing in animal models. We speculate that temporal changes in fMRI signal may indicate respiratory after-discharge and/or habituation phenomena.

Although computed tomography and magnetic resonance imaging have contributed to the ability to identify metastatic disease in head and neck cancer, inadequacies in evaluating lymphadenopathy still exist. This study was undertaken to estimate the accuracy of radiological criteria used to detect cervical lymph node metastases. The morphological characteristics of 957 lymph nodes from 36 neck dissections from patients with squamous cell cancer were examined microscopically. A large number of malignant nodes were found to have diameters of less than 10 mm. Extranodal spread also occurred in a substantial percentage of smaller nodes. Because the present radiological criteria for assessing cervical lymph node status are based largely on size, findings indicate major limitations in the capabilities of detecting metastatic disease. New modalities to improve the staging of head and neck cancer are discussed.

The effectiveness of combining surgery with chemo- and radiation therapy in treatment of human cancer provides a useful model for further development of new multimodality approaches including laser photochemotherapy. Laser endoscopy often is a useful treatment for obstructive tumors in airways, but interstitial laser fiberoptics is becoming a more precise, minimally invasive alternative for ablation of unresectable or recurrent neoplasms. Combining intratumor chemotherapy with laser energy delivery via interstitial fiberoptics should be most effective using drugs activated by photothermal energy. A number of investigators have shown that anthracyclines and cis-platinum are likely candidates for light or heat activation in cancer cells. An advantage of anthracyclines is their dual role as antitumor drugs and as photosensitizers. Because they are effective chemotherapy agents without photoactivation, two approaches are possible to increase tumor responses. Maximum tolerated dose followed by photoillumination via laser fiberoptics can be used to obtain better tumor palliation. Improved treatment response to lower intratumor drug levels after laser activation also should reduce systemic toxicity. Preclinical studies and recent case reports from several groups suggest photochemotherapy with currently approved drugs and lasers may soon become an attractive alternative for treatment of recurrent tumors in cancer patients.