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R Lufkin

Publications and source records attributed to R Lufkin.

At least 19 recordsLinked to original sources
PubMed2000

Midline destructive lesions of the sinonasal tract: simplified terminology based on histopathologic criteria.

BACKGROUND AND PURPOSE: Destructive lesions of the sinonasal tract, lacking a discernible etiology and referred to as midline destructive disease, have been pathologically classified in accordance with a variety of confusing terms. Development of new pathologic concepts and immunohistochemical techniques has provided a fresh understanding of these lesions, and, as a result, they can be unified into two distinct pathologic groups: Wegener's granulomatosis and non-Hodgkin's T-cell lymphoma. METHODS: We retrospectively reviewed the imaging studies and pathologic specimens of seven patients with prior diagnoses included in the midline destructive disease group. The specimens were reviewed by an oral pathologist using currently accepted pathologic criteria and the newly available immunohistochemical markers CD20, CD45, and CD45RO. Lesions were classified as non-Hodgkin's T-cell lymphomas when positive for CD45 and CD45RO and negative for CD20, and as Wegener's granulomatosis in the presence of noncaseating multinucleated giant cell granulomas and necrotizing vasculitis. RESULTS: Three of the lesions were reclassified as Wegener's granulomatosis and four as T-cell lymphomas after applying these pathologic criteria. There were no distinguishing imaging findings between Wegener's granulomatosis and non-Hodgkin's T-cell lymphoma. CONCLUSION: The current pathologic classification for midline destructive disease should be incorporated into the radiologic lexicon and the use of terms from the old classification system, such as idiopathic midline granuloma and lethal midline granuloma, should be abandoned and no longer be used in radiologic reports.

Antigens, CD20↗
PubMed2000

Fenestration surgery for otosclerosis: CT findings of an old surgical procedure.

Numerous attempts to deal surgically with otosclerosis were made before the current method of stapedectomy with stapes prosthesis was established. We report a case with unique CT findings of a patient who underwent fenestration surgery for otosclerosis in the early 1940s. Recognition of this old surgical procedure on the imaging scans may avoid misdiagnosis of labyrinthine fistulae or middle and inner ear malformations.

Aged↗
PubMed1997

Biopsy of hepatic dome lesions: semi-real-time coronal MR guidance technique.

OBJECTIVE: MR imaging, with its coronal imaging capability, may be ideally suited for biopsies of hepatic dome lesions. We are reporting on the successful semi-real-time biopsy of such lesions using a 0.2-T open-configuration MR scanner in five patients. CONCLUSION: MR guidance holds promise for facilitating biopsies of hepatic dome masses.

Adult↗
PubMed1996

Orbit and optic nerve.

The optic nerve is a fiber tract of the brain, and is not a true cranial nerve. Primary pathologic processes seen in the central nervous system and its linings can therefore affect the optic nerve. Along their course the fibers of the visual pathways are also susceptible to secondary extrinsic processes. The MR appearance of many of the primary and secondary processes that affect the optic nerve are characteristic. Where the imaging features of a process are not characteristic, a fairly narrow differential diagnosis can be suggested depending on the imaging appearance and anatomic location of the pathologic entity. This article is a categorical overview of the disease entities that may affect the optic nerve and tracts. Pathologic processes are organized according to the typical sites of involvement along the visual pathways, from the retina to the occipital cortex. Medical imaging, pathologic, clinical, and epidemiological highlights are presented.

Brain Diseases↗
PubMed1995

Early postoperative appearance of radiofrequency lesions on magnetic resonance imaging.

Eleven patients who underwent stereotactic radiofrequency lesions in the central nervous system had magnetic resonance imaging follow-up within 72 hours of surgery to determine the early appearance of their lesions. Eight patients with severe tremor, one with chronic pain, and two with dystonia were analyzed. There were six female patients and five male patients, age 7 to 75 years (mean +/- standard deviation = 42 +/- 21). Magnetic resonance imaging was performed postoperatively at 32 +/- 25 hours (range, 3-72). Postoperative T1-weighted spin echo images demonstrated foci of iso- to hyperintensity surrounded by an edge of hypointensity, and corresponding T2-weighted images showed a lesion with three concentric zones consisting of inner hypointense, middle hyperintense, and outer hypointense zones. Gadolinium increased T1-weighted image lesion visibility, and a ring of enhancement around the zone of hypointensity was observed. Lesions could be seen as early as 3 hours after surgery. The lesions were best shown on gadolinium-enhanced T1-weighted images and on T2-weighted images. The edema surrounding the lesion increased over time, up to the 72 hours studied. These data provide important information on the development of lesion appearance, which may be applied in the development of real-time magnetic resonance imaging monitoring of radiofrequency lesion formation. This technique associated with electrophysiological response and the real-time visualization of the anatomic correlation of the probe may allow for a very precise and selected lesion in the central nervous system for the treatment of functional disorders and brain tumors.

Adolescent↗
PubMed1995

Dynamic MRI-guided interstitial laser therapy: a new technique for minimally invasive surgery.

Interstitial laser therapy (ILT) is a promising therapeutic technique in which laser energy is delivered percutaneously to various depths in tissue. In this study, the authors compared high-speed magnetic resonance imaging (MRI) of ILT in tissues during treatment with post-treatment histopathologic specimens. The use of 5-second MRI scans allowed detection of thermal damage by the 1064-nm neodymium:yttrium-aluminum-garnet laser in ex vivo liver and brain tissues. These tissues were treated by ILT with 20 W of laser output for 5 to 30 seconds via a 600-microns fiberoptic inserted 1 cm into the specimens at a power density of 7 kW/cm2 at the tip of the bare fiber. Sequential MRI measurements of lesion areas made during and after treatment were compared to measurements of laser-induced tissue damage in histopathologic sections. Fast MRI scans and tissue histology both demonstrated increased lesion size with time of ILT. Serial images obtained during ILT detected thermal changes as areas of low signal intensity that exceeded the size of the post-treatment lesions as measured on either final MRI or histology. The thermal effects detectable by these high-speed MRI sequences can be used to monitor laser-induced tissue changes during therapy, thereby providing a valuable noninvasive method for the intraoperative assessment of heat distribution during ILT.

Animals↗
PubMed1995

Preliminary experience with MR-guided thermal ablation of brain tumors.

PURPOSE: To evaluate the feasibility of a technique of MR-guided stereotactic radio frequency ablation, which was developed as a minimally invasive treatment for brain tumors, and to determine MR characteristics and sequential evolution of radio frequency lesions created to ablate brain tumors. METHODS: Fourteen lesions in 12 patients with primary and metastatic brain tumors were treated with this technique and followed for up to 10 months. The stereotactic coordinates of the tumor and the angle of the radio frequency probe were calculated on MR imaging. The radio frequency lesion was generated in the awake patient by increasing the temperature to 80 degrees C within the tumor for 1 minute. This was repeated until the entire tumor volume was destroyed. MR imaging was performed before, during, and immediately after the radio frequency procedure, and sequential MR was obtained during clinical follow-up. RESULTS: MR imaging clearly showed well-defined radio frequency lesions and provided feedback for treatment planning. The radio frequency lesion boundary was well identified as a dark signal rim on T2-weighted images and showed ring enhancement on contrast-enhanced T1-weighted images. The sequential MR imaging showed the radio frequency lesions decreased in volume in all cases, suggesting focal control. CONCLUSION: Stereotactic MR-guided radio frequency brain tumor ablation is a feasible and promising technique that can be an attractive brain tumor treatment alternative. MR provided not only accurate tumor location but also visualization of feedback of thermal tissue changes that reflected therapeutic effect.

Adenocarcinoma↗
PubMed1994

Use of positron emission tomography with fluorodeoxyglucose in patients with extracranial head and neck cancers.

BACKGROUND: The purpose of this study was to evaluate the utility of positron emission tomography- (PET) 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) imaging in extracranial head and neck cancers. METHODS: Sixty patients with biopsy-proven cancers were studied using PET-FDG. Thirty-four patients were studied before therapy (staging), of which 15 patients received primary radiotherapy and serial PET-FDG imaging (monitoring). Seven patients with advanced disease had laser excision (monitoring), and 19 patients were evaluated for recurrent disease (recurrence). RESULTS: Four patients had unknown primary lesions. PET-FDG imaging located the primary tumor in two of four patients, and magnetic resonance imaging (MRI) in none of four. In the remaining patients (staging), PET-FDG imaging detected the primary tumor in 29 of 30 patients, and MRI in 23 of 30. In the staging group, PET-FDG imaging identified the presence or absence of lymph node involvement in 32 of 34 patients, and MRI in 31 of 34. PET-FDG imaging was helpful in evaluating tumor response to radiation therapy or laser excision. Ten patients evaluated for recurrent disease had biopsy-confirmed recurrences, and 7 had no recurrence. PET-FDG imaging results were positive for primary tumor recurrence in 9 of 10 patients, and MRI results were positive in 6 of 10. MRI results were negative for lymph node disease in one of these patients with recurrent primary tumor where PET-FDG imaging and biopsy demonstrated nodal involvement. PET-FDG results were negative for recurrent disease in seven of seven patients, and MRI results were negative for recurrent disease in in four of seven. CONCLUSION: In this series, the authors found that PET-FDG is a useful diagnostic modality for evaluating the patient with an unknown primary, monitoring response to therapy, and in detecting recurrent tumors.

Adult↗
PubMed1994

Somatosensory evoked response source localization using actual cortical surface as the spatial constraint.

We localized right median nerve somatosensory evoked responses in a normal human subject using an equivalent dipole method applied to magnetic field recordings. High resolution, 3-dimensional MRI data were used to confine source locations to the cortical surface. Results localized in Brodmann area 3b corresponding to location of hand somatosensory cortex derived from direct brain stimulation studies. The solution was unique and total computational time for an exhaustive, brute-force search was small and the results realistic due to applied anatomical constraints. This study demonstrates feasibility of accurate, non-invasive, realistic localization of dynamic human cortical function using spatial constraints provided by MRI images.

Adult↗
PubMed1994

Minimally invasive palliative tumor therapy guided by imaging techniques: the UCLA experience.

Imaging-guided palliative therapy of recurrent and/or inaccessible head and neck tumors may soon become clinically practical since sensitive and noninvasive monitoring techniques of energy deposition in tissues are now available. Interstitial tumor therapy (ITT) is a technique whereby a source of energy (laser, radiofrequency, ultrasonic, cryoenergy, etc.) is directly applied into tumors at various depths. Recent studies have demonstrated the efficiency of ultrasound (UTZ) and magnetic resonance imaging (MRI) for real and/or "near" real time tumor and vessel identification as well as monitoring and quantifying energy-induced tissue damage. We now report our initial clinical experience with patients in which UTZ and/or MRI-guided ITT techniques were successfully applied for the treatment of recurrent, nonresectable, local, and/or metastatic head and neck carcinomas. Patients were treated on an outpatient basis either in the operating room or in an upgraded specially equipped SIGNA 1.5T MR suite. Most patients tolerated these procedures well and were successfully palliated for periods ranging from 3 months to 5 years posttreatment. The upgrades introduced in a standard MRI suite, the clinical experience, and future perspectives will be reviewed.

Aged↗
PubMed1994

Dose response of human tumor cells to rhodamine 123 and laser phototherapy.

Previous studies have shown that Rhodamine 123 (Rh123) is an efficient tumor targeting agent for argon laser photodynamic therapy in vitro. Effectiveness of this approach for cancer treatment in vivo will depend on Rh123 tumor uptake kinetics and laser energy delivery via fiberoptics to the tumor site. In the present study, tumor and normal cells were exposed in vitro to 1 micrograms/mL Rh123 until 10%, 50%, and 100% of maximum uptake was achieved. Laser treatment response was monitored by trypan blue exclusion for tumor cell viability and by MTT tetrazolium assays to measure mitochondrial dehydrogenase activity. TE671 fibrosarcoma cells were highly sensitive to argon laser phototherapy (514 nm, 5 W, 1 minute, Tmax = 8 degrees C), with mitochondrial inhibition seen after Rh123 uptake of 12, 50, and 100 ng/million cells. P3 squamous cell carcinoma cells were inhibited 20% and 75% by the laser after Rh123 uptake of 13 or 30 ng/million cells, respectively. M26 melanoma cells were not sensitive to the laser after 15 ng/million cells Rh123 uptake but were inhibited 45% and 75% after Rh123 uptake of 80 and 160 ng/million cells. Micro2 fibroblast mitochondrial activity was reduced less than 25% by the laser after Rh123 uptake of 50 ng/million cells. Cell viability after maximum Rh123 uptake and laser treatment was decreased to 30%, 15%, and 2% for M26 melanoma, P3 squamous cell carcinoma, and TE671 fibrosarcoma cells, but remained over 80% for Micro2 fibroblasts. The results suggest that Rh123 laser treatment response depends on tumor type and drug uptake level, with normal cells being much less sensitive to phototherapy.

Antimetabolites, Antineoplastic↗
PubMed1994

Physiology of the lower eyelid retractors: tight linkage of the anterior capsulopalpebral fascia demonstrated using dynamic ultrafine surface coil MRI.

Although the histologic anatomy of the lower eyelid retractors is well defined, the physiology of the lower retractors has been determined only by interference based on anatomic and clinical findings. In this study, in five normal subjects we investigated the physiology of the lower eyelid retractors utilizing dynamic high resolution magnetic resonance imaging (MRI) with a custom designed surface coil. Measurements of the excursion of the cornea, lower eyelid margin, and anterior edge of the inferior oblique muscle were made from scans taken in upgaze and downgaze. We found that the corneal movement was substantially greater than the movement of the eyelid margin, a finding that can readily be made clinically. A more important result was that the movement of the eyelid margin and the movement of the inferior oblique margin were similar in all cases. Thus, the length of the anterior capsulopalpebral fascia between the tarsus and inferior oblique muscle remains constant in downgaze, and the source of the stretch in the lower eyelid retractors lies in the posterior capsulopalpebral system, at the capsulopalpebral head. High resolution eyelid MR has great potential to allow investigation of essential aspects of normal and pathologic eyelid anatomy and physiology.

Adult↗
PubMed1993

Overview of MR imaging modalities.

Practical approaches to optimization of the use of gadolinium in MR imaging comprise a range of advances in data-acquisition techniques and pulse sequences that augment tissue contrast and reduce scanning times, increasing throughput and patient comfort. In addition to the effects of magnetic field strengths and manipulation of contrast doses for routine spin-echo (SE) imaging, several approaches are reviewed. These include: fat suppression, which helps to resolve enhancing lesions from tissues with inherently high signal on post-gadolinium T1-weighted imaging; gradient-echo (GRE) and partial radio-frequency (RF) echoplanar techniques, which tend to reduce data acquisition times; MR angiography, which enables elucidation of slow-flow vessels and mass-vessel relationships; and three-dimensional GRE scan displays, which relate lesion location to regional and surface anatomy.

Angiography↗
PubMed1993

Change induced by radiation therapy in FDG uptake in normal and malignant structures of the head and neck: quantitation with PET.

PURPOSE: To quantitate the changes induced in uptake of the glucose analog 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in normal structures in the head and neck and compare these to the change in uptake in malignant structures in patients with head and neck tumors undergoing radiation therapy. MATERIALS AND METHODS: Eleven patients with biopsy-confirmed squamous cell carcinoma of the head and neck were studied before, during, and after a 6-week course of radiation therapy with positron emission tomography (PET)-FDG imaging. A ratio of FDG uptake in the structure compared with that in the cerebellum (termed metabolic ratio) within and outside of the field of radiation was determined in the adenoids; lingual and palatine tonsils; parotid, submandibular, and sublingual glands; and nasal turbinates, soft palate, and gingiva. RESULTS: The average metabolic ratio in the tonsils, nasal turbinates, soft palate, and gingiva did not change significantly with treatment. CONCLUSION: FDG uptake in normal structures does not change with radiation therapy. This fact is in marked contrast to the FDG uptake in squamous cell carcinomas in the head and neck, which decrease dramatically with treatment (P < .005).

Adenoids↗
PubMed1992

Activity of medial mesopontine units during cataplexy and sleep-waking states in the narcoleptic dog.

Narcolepsy has been hypothesized to be a disease of rapid eye movement (REM) sleep. According to this hypothesis, cataplexy is a result of the triggering during waking of the mechanism that normally serves to suppress muscle tone in REM sleep. REM sleep control mechanisms have been localized to the pons. Narcoleptic dogs have increased numbers of cholinergic receptors in the medial pons. These findings suggest that neurons mediating the triggering of cataplexy might be located in medial pontine regions. In the present study, this hypothesis has been investigated by recording the discharge of units in the medial mesopontine region of the narcoleptic dog. Unit activity was examined in the nucleus reticularis pontis oralis, caudalis, and central gray, with each cell being recorded during both cataplexy and sleep states. Maximal discharge rates were observed, in all of these regions, during active waking states (mean rate, 45.3/sec) and REM sleep (16.0/sec), with minimal discharge rates in non-REM sleep (8.3/sec). Unit discharge was reduced in cataplexy relative to precataplexy periods. Cataplexy discharge rates were 8.3/sec, 52% of the mean REM sleep rate. Cataplexy discharge rates were also significantly lower than those at REM sleep onset. Cataplexy discharge rates were comparable to rates in quiet waking and non-REM sleep. While medial mesopontine neurons discharge at high rates in REM sleep, they have little or no activity in cataplexy. We interpret the lack of activation of medial mesopontine units in cataplexy as indicating that the characteristic phasic motor activation of REM sleep does not occur in this state.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗