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Biomedical subjects

R C Lange

Publications and source records attributed to R C Lange.

At least 37 records · Page 2Linked to original sources
PubMed1996

Refractory epilepsy: comparison of MR imaging, CT, and histopathologic findings in 117 patients.

PURPOSE: We compared computed tomography (CT) and magnetic resonance (MR) imaging for the detection of abnormalities underlying epilepsy. MATERIALS AND METHODS: CT and MR imaging findings in 117 patients (56 female, 61 male patients; age at surgery, 12-56 years) who underwent surgery for medically refractory epilepsy were compared with histopathologic findings by using the McNemar and chi 2 statistics. RESULTS: Sensitivities for detecting abnormalities were 95% (104 of 109) for MR imaging and 32% (35 of 109) for CT; specificities were 87% (13 of 15) for MR imaging and 93% (14 of 15) for CT (P < .001 for MR versus histopathologic findings). In the subgroup of 113 patients with solitary findings, MR imaging depicted an abnormality at the surgical site in 86% (n = 97) of 113 patients compared to 28% (n = 32) for CT (P < .001). In this same subgroup, histopathologic findings were predicted by using MR imaging in 88% (n = 99) of 113 patients versus 35% (n = 40) with CT (P < .001). Multiple findings were observed in 3% of CT (three of 117) and 17% of MR (20 of 117) images. CONCLUSION: CT has no role in the diagnostic evaluation of medically refractory epilepsy. Even in patients with medically controlled epilepsy, use of less costly CT instead of MR imaging seems imprudent.

Adolescent↗
PubMed1996

Mammographic findings of recurrent breast cancer after lumpectomy and radiation therapy: comparison with the primary tumor.

PURPOSE: To compare the mammographic findings of recurrent breast cancer with those of the primary tumor in patients who underwent lumpectomy and radiation therapy. MATERIALS AND METHODS: Mammograms were reviewed of primary and recurrent tumors in 25 patients (26 lesions). Mammographic appearance, location, and histopathologic characteristics were retrospectively compared between primary and recurrent tumors. RESULTS: Primary and recurrent tumors were mammographically similar in 21 (81%) of the 26 lesions. Of 14 primary tumors with calcifications, 12 (86%) recurred with calcifications, and of the 12 masses, nine (75%) recurred as masses. Recurrent tumors that occurred in the lumpectomy quadrant were more often similar in mammographic appearance to the primary tumor (20 of 22 tumors) than those in other quadrants (one of four tumors) (P < .02). CONCLUSION: After conservative treatment of breast cancer, the majority of recurrent tumors appear to be mammographically similar to primary tumors. It is prudent to review preoperative mammograms during follow-up of patients after lumpectomy and radiation therapy.

Adult↗
PubMed1995

MR characteristics of neoplasms and vascular malformations associated with epilepsy.

We assessed the magnetic resonance (MR) imaging characteristics of two categories of epileptogenic substrates, neoplasms, and vascular malformations, to determine MR sensitivity and typical imaging features. A blinded retrospective analysis was performed on MR scans from 41 patients who had a neoplasm or vascular malformation surgically resected as treatment for medically refractory epilepsy. Abnormalities were assessed for sensitivity of MR detection, prediction of pathologic category, location, calvarial remodelling, signal intensity, and effect on adjacent tissue. Pathologic findings consisted of 33 tumors and 8 vascular malformations. We correctly localized 100% of the 41 lesions and predicted the correct pathologic category for 95% of these lesions. Neoplastic and vascular lesions (NVLs) associated with epilepsy had certain characteristic features. The temporal lobe was the most common site for NVL, involved in 68%. NVL were located in the brain periphery in 85% and remodelled the calvarium in 32%. NVL were associated with mass effect in 61%, volume loss in 1%, and no effect on adjacent tissue in 37%. NVL associated with epilepsy can be detected with high sensitivity using MR imaging. The temporal lobe location, cortical involvement, and calvarial remodelling are findings typical of NVL. MR characteristics can successfully predict the pathologic substrate of these lesions.

Brain Neoplasms↗
PubMed1995

Clinical stage I endometrial carcinoma: pitfalls in preoperative assessment with MR imaging. Work in progress.

PURPOSE: To identify potential pitfalls in using magnetic resonance (MR) imaging to determine the depth of myometrial invasion in patients with clinical stage I endometrial carcinoma. MATERIALS AND METHODS: Forty women with clinical stage I endometrial carcinoma underwent preoperative pelvic MR imaging. Uterine length, tumor signal intensity, appearance of the junctional zone, presence of large polypoid tumors, leiomyomata, and congenital uterine anomalies were analyzed. Univariate logistic-regression analysis was performed to identify associations between incorrect MR staging and these variables. RESULTS: MR staging of IA, IB, and IC disease was 55% accurate (22 of 40 cases); MR differentiation of deep myometrial invasion (stage IC) from superficial disease (stages IA and IB) was 78% accurate (31 of 40 cases). Older age (P = .025), presence of polypoid tumors (P = .025), and difficulty in pathologic staging (P < .005) were significantly associated with incorrect MR assessment. CONCLUSION: When present, large polypoid tumors, leiomyomata, congenital anomalies, small uteri, and indistinct zonal anatomy may make it difficult to assess myometrial invasion at MR imaging.

Aged↗
PubMed1995

Acute flank pain: comparison of non-contrast-enhanced CT and intravenous urography.

PURPOSE: To compare non-contrast-enhanced computed tomography (CT) and intravenous urography (IVU) in the evaluation of patients who present with acute flank pain and in whom ureteric obstruction is suspected. MATERIALS AND METHODS: The findings at non-contrast-enhanced CT and IVU in 20 patients with acute flank pain were compared for the presence or absence of ureteric obstruction and delineation of ureteric stones. RESULTS: Twelve of the 20 patients had non-contrast-enhanced CT and IVU findings consistent with ureteric obstruction. Of these 12 patients, five had a ureteric stone that was demonstrated on both non-contrast-enhanced CT scans and IVU radiographs, six had a stone that was depicted on non-contrast-enhanced CT scans only, and in one patient a stone could not be delineated definitively on either non-contrast-enhanced CT scans or IVU radiographs. Eight patients had findings at non-contrast-enhanced CT and IVU consistent with the absence of obstruction. CONCLUSION: Non-contrast-enhanced CT is more effective than IVU in precisely identifying ureteric stones and is equally effective as IVU in the determination of the presence or absence of ureteric obstruction.

Acute Disease↗
PubMed1993

Pelvic MR imaging findings in gestational trophoblastic disease, incomplete abortion, and ectopic pregnancy: are they specific?

Thirty-nine patients with abnormally elevated levels of serum beta subunit of human chorionic gonadotropin (beta-hCG) were studied to determine whether findings at magnetic resonance (MR) imaging are specific for primary molar disease, persistent gestational trophoblastic disease (GTD), incomplete abortion, and ectopic pregnancy. Among the latter three groups, the only significant differences were a higher prevalence of endometrial distention in the group with incomplete abortion (P < .0035) and the absence of junctional zone disruption in the group with ectopic pregnancy (P < .05). In the group with primary molar disease, total intrauterine volume was significantly increased (P < .001), and endometrial distention and presence of an endometrial mass had a significantly higher prevalence than that in the persistent GTD groups with (P < .04) or without (P < .001) metastases. Myometrial or extrauterine disease was identified in 65% of the patients with persistent disease and a beta-hCG level greater than 500 mIU/mL (500 IU/L). Thus, although MR imaging findings in persistent GTD, incomplete abortion, and ectopic pregnancy are relatively nonspecific, MR imaging can depict invasive disease that may alter therapeutic management in patients with documented GTD.

Abortion, Incomplete↗
PubMed1992

Fast spin-echo MR imaging of the female pelvis. Part I. Use of a whole-volume coil.

In this prospective study, axial and sagittal magnetic resonance (MR) images were obtained with T2-weighted conventional spin-echo (CSE) and fast spin-echo (FSE) sequences in 34 consecutive female patients who underwent clinical pelvic MR examination at 1.5 T. The MR images from each patient were compared side by side, blindly and independently, by two radiologists experienced in MR imaging who used a standardized score sheet for anatomic and pathologic findings. The FSE sequences were rated superior significantly more often than the CSE sequences in most categories of findings (P less than .05), including overall image quality and reduction of motion artifact. The examination time for the FSE sequences was 1 minute 46 seconds versus an examination time of 9 minutes 14 seconds for the CSE sequences. (Both CSE and FSE sequences provided 18 sections.) It is concluded that the FSE sequence provides T2-weighted anatomic and pathologic information superior to that provided by the CSE sequence and requires substantially less imaging time.

Adolescent↗
PubMed1992

Multicoil high-resolution fast spin-echo MR imaging of the female pelvis.

A fast spin-echo pulse sequence was combined with multiple surface coils used simultaneously in the form of a "multicoil" in magnetic resonance imaging studies of the female pelvis. This combination allowed maximal resolution with maintenance of the signal-to-noise ratio (S/N) at an acceptable level, and the S/N with the multicoil system was substantially better than that achieved with a body coil. Excellent image quality and demonstration of anatomic detail were afforded by use of this technique.

Adolescent↗
PubMed1992

Thyroid uptake neck phantoms are not created equal.

The main purpose of this communication is to alert nuclear medicine departments to the fact that the earlier version of the water phantom grossly overestimates soft-tissue attenuation in the neck, resulting in calculated thyroid uptake values which are significantly overestimated (in hyperthyroid patients we noted uptake values approaching or exceeding 100%). We believe that the solid Lucite phantom (which is the one recommended by IAEA) better approximates the human neck soft tissue overlying the thyroid. Institutions that continue to use the water phantom should be aware that their thyroid uptakes will be relatively elevated and the normal range must be shifted accordingly. Our normal range is 10%-30% uptake of 123I at 24 hr for the Lucite phantom. For the water phantom, the estimated normal range would be 15%-45%. In addition, the phantom type should be considered when comparing uptake results with those from another institution for a particular patient. Also, treatment doses for Grave's disease could be significantly affected, if such doses are calculated by a formula that depends on uptake.

Equipment Design↗
PubMed1991

An evaluation of MRI contrast in the uterus using synthetic imaging.

Using a 1.5-T system, we investigated the contrast in MR images of the uterus using a synthetic imaging program that was capable of producing images with TR values of 20 to 10220 ms and TE values of 1 to 511 ms. Synthetic images were calculated from images obtained on six normal women of reproductive age. The synthesized uterine images were essentially indistinguishable from acquired images with the same TR and TE parameters. Cervical and uterine anatomy could be clearly differentiated in synthetic images with a TE = 80 ms when the TR was as low as 100 ms. We conclude that the zonal anatomy of the uterus can be demonstrated using TR values that are much lower than those usually used for demonstrating uterine anatomy.

Cervix Uteri↗
PubMed1991

Uterine changes after dilation and curettage: MR imaging findings.

To determine what, if any, changes occur in the appearance of the uterus on magnetic resonance (MR) images after dilation and curettage (D&C), nine women without endometrial abnormality underwent imaging before D&C and on day 2 and day 7 after D&C. On day 2, markedly hypointense curvilinear areas in the endometrial canal were noted on MR images in all patients (P = .0002). By day 7, these areas decreased in size in five (62%) and completely resolved in the rest (P = .022). There was no significant change in the width of the endometrial stripe or in the width or signal intensity of the junctional zone or myometrium after D&C. The junctional zone was focally disrupted in one patient who underwent D&C that was complicated by a uterine perforation. Therefore, curvilinear areas of low signal intensity (most likely representing clot) in the endometrial canal were visualized on MR images within 2 days of uncomplicated D&C and decreased in size or resolved over time. Significant widening of the endometrial stripe or disruption of the junctional zone was not observed after uncomplicated D&C.

Adult↗
PubMed1991

Chemical shift artifact: dependence on shape and orientation of the lipid-water interface.

On magnetic resonance images, chemical shift artifact (CSA) can be seen at a planar lipid-water interface oriented within the plane of the phase-encoding and section-select directions (ie, perpendicular to the frequency-encoding direction). Phantoms and a clinical case were used to demonstrate that when a lipid-water interface is curvilinear (eg, spherical) or planar but not oriented along the section-select direction, CSA may be absent or diminished. This effect can be seen at interfaces of normal structures (kidneys, bladder) as well as at interfaces with pathologic lesions such as lipid-containing dermoids. Not only is this effect dependent on section thickness, field of view, matrix size, and receiver bandwidth, but it is also strongly dependent on the orientation of the interface with respect to the section-select direction. Knowledge of the factors that can alter CSA is important since it is used to distinguish lipid-containing from nonlipid-containing structures of similar signal intensities.

Adult↗
PubMed1989

Detection of esophageal motor disorders by radionuclide transit studies. A reappraisal.

Radionuclide measurement of esophageal transit has been proposed as a screening test for esophageal motor dysfunction. In this study we evaluated the radionuclide esophageal transit test in 49 consecutive patients undergoing esophageal manometry for esophageal motor disorders. Esophageal transit was assessed using a 10-ml water bolus labeled with 250 microCi technetium-99m sulfur colloid. In preliminary studies in 14 healthy controls, mean transit time was 9.6 +/- 2.1 (SD) sec. Prolonged transit (greater than 15 sec) was observed in two of 28 swallow sequences in the control subjects. Transit times were prolonged in all patients with achalasia or diffuse esophageal spasm, and in five of seven patients with nonspecific abnormalities of peristaltic progression. The test was abnormal in only three of seven patients with high-amplitude peristalsis (nutcracker esophagus) and in none of three patients with hypertensive lower esophageal sphincter. Additionally, prolonged transit was seen in two of 18 patients with normal manometry. We conclude that the radionuclide transit test using a liquid bolus successfully identifies motor disorders characterized by defective peristaltic progression but not disorders in which peristalsis is intact. A major limiting factor appears to be the small number of swallow sequences tested. The test may not, therefore, be accurate enough to consider adopting as a sensitive and noninvasive screening test in the evaluation of patients with suspected esophageal motor disorders.

Adult↗
PubMed1989

Coil holder and marker system for MR imaging of the total spine.

To improve the efficiency of magnetic resonance imaging of the total spine, the authors developed a coil holder and marker system to accurately localize the level of the spine imaged. The patient's external auditory canal and the alignment light on the imager are lined up with marks on the coil holder. The spine is then imaged in three segments by using a 24-cm field of view. The device has been successful in 20 of the 23 patients in whom it was used. The three failures were due to technical problems.

Humans↗
PubMed1989

The role of nifedipine therapy in achalasia: results of a randomized, double-blind, placebo-controlled study.

Utilizing the rationale that the calcium channel blocker nifedipine decreases lower esophageal sphincter pressure, we performed a double-blind, placebo-controlled, crossover trial of sublingual nifedipine in achalasia, a disorder whose treatment depends on reduction in lower esophageal sphincter pressure. Ten patients participated in this trial, completed diaries, underwent manometric determinations of lower esophageal sphincter pressure, and had testing of esophageal emptying rates by a solid-meal radionuclide method. Nifedipine, titrated to a dose of 10-30 mg before meals, was well tolerated. Compared with placebo, nifedipine significantly reduced the frequency of dysphagia, but some symptoms of dysphagia, regurgitation, or nocturnal cough were still present most days. Nifedipine significantly reduced lower esophageal sphincter pressure by 28%, a value approximately one-half that achieved by successful pneumatic dilatation or myotomy. Esophageal emptying rates, as determined by the radionuclide method, were unchanged by nifedipine. We concluded that 1) nifedipine reduces symptoms of achalasia, but substantial symptoms do remain during such therapy; 2) the suboptimal effect results from the limited, although statistically significant, effect of nifedipine on reduction of lower esophageal sphincter pressure; and 3) although we believe that nifedipine may be recommended as treatment for achalasia in the subset of patients whose overall medical condition places them at high risk for forceful dilatation or surgery, it cannot be recommended as a standard alternative to these other modalities.

Administration, Sublingual↗
PubMed1987

Identification and mechanism of delayed esophageal acid clearance in subjects with hiatus hernia.

To determine if hiatus hernia (HH) contributes to the delayed clearance of acid from the esophagus in patients with gastroesophageal reflux (GER), we performed simultaneous esophageal pH recordings and radionuclide studies in three study populations: 12 GER patients with HH, 5 GER patients with no HH, and 8 subjects with HH but no GER symptoms. Acid clearance was measured at 5 cm. above the manometrically located lower esophageal sphincter (LES) after injecting a 15-ml. bolus of 0.1 N HCl at 15 cm. above the LES. The acid was labeled with 200 mu Ci of 99mTc-sulfur colloid. Acid clearance was also measured at 10 cm. above the LES after injection of a 15-ml. bolus of 0.1 N HCl at 20 cm. above the LES. Acid clearance at 5 cm. above the LES was faster in GER patients with no HH compared to GER patients with HH and asymptomatic HH subjects. Acid clearance was faster at 10 cm. than 5 cm. above the LES in all HH and non-HH subjects studied. In non-HH subjects, each swallow resulted in an increase in pH (a monophasic pH response) at 5 and 10 cm. above the LES. In symptomatic as well as asymptomatic HH subjects, swallows resulted in an initial fall followed by a rise in pH at 5 cm. above the LES (a biphasic pH response). Radionuclide studies showed reflux of the isotope-labeled acid into the esophagus followed by clearance (a biphasic response) accompanying swallows in 15 of the 20 HH subjects. Swallow-induced reflux was not detected by radionuclide scanning in non-HH subjects. Based on these observations, we conclude that during acid clearance a small amount of acid is trapped in the HH sac and refluxes into the esophagus during subsequent swallows when there is relaxation of the LES, and these repeated episodes of acid reflux from the HH account for the delayed acid clearance observed in GER patients with HH.

Adult↗