Sentinel lymph node biopsy identifies occult nodal metastases in patients with Marjolin's ulcer.

Since Marjolin's description, the management of burn scar carcinoma has remained controversial. A multitude of options and recommendations exist for the management of both primary lesions and regional nodal metastasis. This work reviews six cases of Marjolin's ulcer staged using sentinel lymph node biopsy. All primary lesions were confirmed to be squamous cell carcinoma and occurred a median of 29.5 years after burn. No patient had clinically detectable lymphadenopathy. In all cases, preoperative lymphoscintigraphy successfully identified a single draining regional nodal basin. Subsequent intraoperative lymphatic mapping/sentinel lymph node (SLN) biopsy was successful in five of six cases (83%). A successful intraoperative lymphatic mapping/SLN biopsy was defined as the identification of blue (uptake of isosulfan blue dye) or "hot" (uptake of radiolabeled sulfur colloid as measured with a handheld gamma counter) node(s) and subsequent excision. Four of five SLN biopsies identified previously occult nodal metastasis. SLN biopsy represents a minimally invasive and accurate staging procedure for Marjolin's ulcer.

Imaging of puerperal septic thrombophlebitis: prospective comparison of MR imaging, CT, and sonography.

OBJECTIVE: Our objective was to compare prospectively the abilities of MR imaging, CT, and sonography to reveal puerperal septic thrombophlebitis in the pelvis. SUBJECTS AND METHODS: Seventy-six women with puerperal fever for 5 days refractory to antimicrobial therapy underwent MR imaging, CT, and sonography. We obtained unenhanced axial CT images followed by enhanced images after the administration of an oral contrast agent for which we followed a specific protocol. Axial T1- and T2-weighted spin-echo MR images with phase reconstruction and sagittal T1-weighted MR images were obtained. Real-time sonography was performed using Doppler color flow mapping and spectral waveform analysis. RESULTS: Of the 76 women, 64 completed studies with all three techniques. Ovarian vein thrombosis was diagnosed in 12 women. True-positive results were indicated when at least two of the three studies showed the presence of a clot; true-negative results were indicated when at least two of the three studies showed a lack of thrombosis. MR imaging and CT revealed both ovarian veins in all cases (64/64). Sonography revealed 33 (52%) of 64 right ovarian veins and 15 (23%) of 64 left ovarian veins. MR imaging (sensitivity, 92%; specificity, 100%) and CT (sensitivity, 100%; specificity 99%) were comparable in all but two cases. In one such case, MR imaging showed patency, CT revealed findings interpreted as thrombosis, and sonography showed flow in the partially occluded vein. In the second such case, bilateral thrombosis was seen on CT, but interpretations based on sonography and MR imaging were left-sided thrombosis only. Sonography correctly revealed six of the 12 cases of ovarian vein thrombosis. CONCLUSION: CT and MR imaging proved to be the studies of choice in the evaluation of ovarian vein thrombosis.

Magnetic resonance imaging of pulmonary embolism.

Magnetic resonance imaging (MRI) has the unique ability to demonstrate pulmonary emboli, venous thrombosis, and normal pulmonary arteries in a single noninvasive study. Spin echo and gradient echo pulse sequences take advantage of the natural high contrast between flowing blood and intraluminal thrombus or embolus. Magnetic resonance angiographic (MRA) techniques offer three-dimensional display of the pulmonary vasculature. Each of these techniques may be viewed in cinematic fashion to depict hemodynamic changes associated with the cardiac cycle. Clinical studies have demonstrated sensitivity in the 75% to 100% range and specificities between 42% and 90% depending on technique. MRI technology is still rapidly advancing and clinical accuracy will no doubt improve as experience with new techniques develops. At present, MRI should play a complimentary role to conventional methods of diagnosing thromboembolic disease.

A comparison of three gastric lavage methods using the radionuclide gastric emptying study.

To determine the percentage of liquid gastric contents experimentally removable by available orogastric lavage systems, five healthy young volunteers were asked to ingest 1 mCi of liquid technicium-99m diethylenetriaminepentaacetic acid (Tc99m-DTPA) mixed with 50 ml tap water. Five minutes afterwards, the radionuclide was lavaged using one of three different techniques-a single syringe method, a closed gravity drainage system, and a closed double syringe method--while continuous radioisotope camera images were taken. Control images, with no lavage performed, were also taken. All of the orogastric lavage methods removed a mean of between 80% and 85% of the stomach contents. The double syringe method was the quickest, while the single syringe method was least tolerated. When compared with control, none of the lavage techniques pushed gastric contents into the duodenum. Thus, in terms of amount of liquid gastric contents removed, there was no one method that removed more than the others. Caution should be exercised in assuming that 80-85% of a liquid gastric ingestion can be removed by lavage in the uncontrolled clinical setting. The use of any orogastric lavage for ingestion evacuation should be undertaken knowing that it is a morbid procedure and usually not necessary.

Angiographic ablation of mediastinal parathyroid adenomas: local experience and review of the literature.

PURPOSE: To evaluate local experience with a modified technique for angiographic ablation of mediastinal parathyroid adenomas. PATIENTS AND METHODS: Three patients with likely mediastinal parathyroid adenomas that had single feeding arteries underwent attempted arteriographic ablation with a slow continuous infusion of contrast medium. Patients were closely monitored for symptoms and calcium dynamics immediately postprocedure and then on a long-term outpatient basis. RESULTS: All three patients were cured (follow-up 22 to 68 months) with no long-term complications. CONCLUSION: Percutaneous angiographic ablation with contrast medium is a reasonable alternative for patients with hyperparathyroidism due to a mediastinal adenoma who can be treated in centers with well-trained interventional radiologists.

Pulmonary embolism: comparison of MR images with radionuclide and angiographic studies.

PURPOSE: To assess the accuracy and potential of magnetic resonance (MR) imaging in evaluation of patients in whom pulmonary embolism is suspected. MATERIALS AND METHODS: Blinded, prospective interpretations of multiphasic, cardiac-gated spin-echo MR images were compared with retrospective chart review in 86 patients in whom pulmonary embolism was suspected. In 64 patients, the presence or absence of pulmonary emboli was established with x-ray angiography (n = 34) or ventilation-perfusion (V-P) scans and concurrent clinical impression (n = 30). RESULTS: In the subgroup with angiographic proof, MR imaging had a sensitivity of 90%, specificity of 77%, positive predictive value of 86%, and negative predictive value of 83%. In 21 patients with intermediate probability of pulmonary embolism on V-P scans and angiograms, MR images enabled diagnosis of pulmonary embolism in 12 of 12 patients (sensitivity, 100%) and absence of pulmonary embolism in seven of nine patients (specificity, 78%). CONCLUSION: MR imaging reliably depicts large and medium-size pulmonary emboli, regardless of infiltrates or effusion; hence, it may clarify findings on V-P scans that show intermediate probability of pulmonary embolism or are at variance with the clinical impression.

The pelvis after cesarean section and vaginal delivery: normal MR findings.

OBJECTIVE: In postpartum women, pain and fever can indicate serious complications, such as phlegmon or abscess of the parametrium or bladder flap, ovarian vein thrombosis, or uterine dehiscence. The purpose of this study was to ascertain the MR appearance of the normal pelvis after uncomplicated cesarean section and vaginal delivery. SUBJECTS AND METHODS: Twenty-two patients (14 who had cesarean sections and eight who had vaginal deliveries) were imaged with a superconducting 0.35-T MR system 1-5 days after delivery. Sagittal and axial T1-weighted, proton density-weighted, and T2-weighted spin-echo images were acquired. Phase reconstruction of the axial T1-weighted sagittal images was performed to confirm flow in the ovarian veins. The ovarian veins, parametrium, bladder flap, endometrium, and uterine incision were analyzed on all images. RESULTS: The uterine incision was well seen in all 14 patients who had cesarean section. The signal characteristics of the incision suggested subacute hematoma within the myometrium, and no myometrial defects were seen. In all 13 patients with a low transverse incision, a hematoma of the bladder flap was seen. Patency was confirmed in the majority of ovarian veins (39/44). No evidence of parametrial edema or mass, which can be seen in abscess or phlegmon, was found in any of the 22 patients. The ovarian perivenous fat did not show edema, which can indicate acute ovarian vein thrombosis. Increased signal in the endometrial cavity was seen in all patients; the signal characteristics were similar to those of subacute hematoma, consistent with clinical findings. CONCLUSION: Normal findings of the postpartum pelvis on MR imaging are subacute hematoma in the uterine incision, bladder flap, and endometrial cavity. Patent ovarian veins are demonstrated in most (89%) cases.

Low resolution spin echo: a simple timesaving technique for MRI liver exams.

MR evaluation of the liver at mid-field strength requires relatively lengthy T2-weighted sequences (T2W) for differentiation of benign cavernous hemangiomas from malignant lesions. A short duration T2W, which maintains standard signal-to-noise ratio and also contrast relationships, can be easily implemented by increasing the pixel size in the phase-encoding direction (thus reducing spatial resolution) and proportionally decreasing the number of phase-encoding steps in the matrix (thus reducing acquisition time). Blinded interpretations of a quick (4 min), low resolution (3.4 mm x 1.7 mm pixel) T2W sequence (matrix 64 x 256, FOV 21.7 cm phase x 43.5 cm frequency) were compared to the 17 min standard resolution (1.7 mm x 1.7 mm) T2W sequence (256 x 256 matrix, FOV 43 x 43 cm) in 25 patients suspected of having liver metastasis. Lesions felt to be cavernous hemangiomas showed a 100% (24/24) agreement for interpreter "A" and 96% (22/23) agreement for interpreter "B" when 4 min low resolution T2W was compared to the standard 17 min sequence. Sensitivity (for all types of lesions) of the low resolution T2W sequence ranged from 100% (31/31) for interpreter "A" to 80% (28/35) for interpreter "B." Missed lesions (interpreter "B") were either partially obscured by excessive fat (wrap around) (N = 4), less than 1 cm in size (N = 2), or degraded by motion artifact (N = 1). Thus in many situations low resolution T2 may provide a substantial timesaving alternative to standard T2W particularly where T2W is used primarily for lesion classification in normal sized patients.

A MRI gradient waveform model for automated sequence calibration.

In order to set up magnetic resonance imaging (MRI) procedures of arbitrary voxel dimensions, slice orientation, and sequence timing in a reasonable time, some form of automatic gradient pulse calibration is required. One such method, involving simulation of gradient waveforms, is presented. Waveforms are modeled based on measurements of the step response. The model used divides each transition into three time regions: a "start" region in the first 0.3 ms, a "slew" region, and a "tail" region representing decay of the eddy current compensation error. In the "slew" region, the time derivative of the gradient, G' (t), is expressed as a function of G(t). The first two regions are nonlinear with respect to demand. The mean error in the simulated gradient is generally less than 0.04 mT m-1 in spin echo sequences. Image signal/noise ratios resulting from sequences calibrated using the model are within 5% of those of empirically calibrated sequences.

Osteomyelitis: characteristics and pitfalls of diagnosis with MR imaging.

Prospective and retrospective magnetic resonance (MR) imaging (0.35-T) interpretations were compared with final diagnoses in 110 patients suspected to have osteomyelitis. Diagnostic criteria of dark marrow on T1-weighted images and bright marrow on short-tau inversion-recovery images yielded a prospective sensitivity of 98% and a prospective specificity of 75%. Sixty percent of uncomplicated septic joint effusions demonstrated abnormal marrow signal intensity that was mistaken for osteomyelitis. Retrospective review revealed that overall specificity could be improved to 82% without loss of sensitivity if increased marrow signal intensity on T2-weighted images were included as an additional criterion. Specificity may be further increased by use of knowledge of morphologic patterns that distinguish various forms of osteomyelitis. Ten patients (9%) had potential pitfall diagnoses (eg, fracture, infarction, healed infection) that mimic osteomyelitis. MR imaging can be sensitive and specific for osteomyelitis if characteristic appearances and pitfall diagnoses are incorporated into the diagnostic criteria.

Deep venous thrombosis of extremities: role of MR imaging in the diagnosis.

Current noninvasive imaging techniques for diagnosis of deep venous thrombosis (DVT) of extremities are limited in their ability to demonstrate central vein involvement and to distinguish acute from chronic changes. The utility of spin-echo magnetic resonance (MR) imaging for DVT was evaluated in 100 patients suspected of having either upper- (n = 25) or lower-extremity (n = 75) DVT. Ninety-seven patients were imaged successfully. In a subset of 36 patients, prospective comparison of MR imaging with contrast venography revealed a sensitivity of 90%, specificity of 100%, and Kappa level of agreement of .752 (P less than .0001). MR imaging showed more central extent of thrombus than did venography in all five patients with upper-extremity DVT and in 13 of 25 patients (52%) with lower-extremity DVT. Although all patients in the study were evaluated for acute symptoms, 13 of 59 (22%) MR imaging studies positive for DVT demonstrated chronic disease. MR images demonstrated ancillary abnormalities in 18 of 41 (44%) patients who did not have DVT. Thus, MR imaging has a role as the definitive examination when the results of initial screening studies are unsatisfactory, or as a first-line examination if (a) there is suspicion of upper-extremity or pelvic vein thrombosis, (b) there is a history of prior DVT that necessitates distinction of acute from chronic changes, or (c) other tests are unavailable.

Noninvasive localization of parathyroid adenomas: a comparison of X-ray computerized tomography, ultrasound, scintigraphy and MRI.

Thirty-two (32) patients with primary hyperparathyroidism (17 with prior localization surgery, 15 without) were studied by a combination of computed tomography (CT), ultrasound (US), nuclear medicine (NM), and magnetic resonance imaging (MRI) for parathyroid adenoma localization. The sensitivity and true-positive ratio of each imaging technique and various combinations of techniques were evaluated. Of the 28 proven parathyroid adenomas (27 by surgery, 1 by digital subtraction angiography), 24 were imaged by two techniques, 19 by three techniques, and 10 by all four imaging techniques. The sensitivities were NM (65%), CT (76%), US (77%), and MRI (81%). The differences between true-positive ratios of 82%, 64%, 71%, and 77%, respectively, were not statistically significant. If multiple techniques were considered as a single test (i.e., a positive localization requires two or more tests to be positive at the same location), then sensitivity for a two-study combination was 79% and true-positive ratio 86%. Three techniques showed a sensitivity of 63% and a true-positive ratio of 92%, four modalities 40% and 100%, respectively. There was no significant difference in the various combinations of techniques employed (e.g., CT and US, US and MR, NM and MR, etc.). Thus, there appears to be an advantage in performing multiple techniques (regardless of which combination is selected) until two tests are positive at the same location.

Treatment of the seronegative spondyloarthropathies with sulfasalazine.

Three patients with reactive arthritis and 2 with ankylosing spondylitis resistant to therapy with nonsteroidal antiinflammatory drugs were treated with enteric coated sulfasalazine in an open trial. Significant toxicity was not observed; 1 patient discontinued sulfasalazine because of gastrointestinal symptoms. As a group, statistically significant improvement was observed in 50 foot walk time, morning stiffness, and hemoglobin concentration. One patient went into complete clinical remission, 2 improved, 1 showed no change, and 1 worsened. Asymptomatic colonic inflammation was found in each of 4 patients examined before beginning therapy. Changes in bowel pathology did not parallel changes in joint symptoms. Sulfasalazine may be a safe and useful therapeutic modality in patients with chronic reactive arthritis or ankylosing spondylitis.

Venous thrombosis: clinical and experimental MR imaging.

Five venous thrombi were induced in the external jugular veins of three laboratory dogs, and were repeatedly imaged over 3 weeks using a 0.35-T magnetic resonance (MR) imager. MR magnitude and phase images, T1 and T2 relaxation times, venography, and histologic sections of these thrombi were evaluated to determine the changes in appearance on MR images with time. Venous thrombi appeared hyperintense compared with muscle on both relatively T1- and T2-weighted spin-echo sequences regardless of the age of the clot. Organization of the thrombus beyond 1 week was manifested as increased prominence of flow signal void in and around the clot. Distinction between intraluminal thrombus and flow-related artifacts was aided by phase image reconstruction. Nineteen venous thrombi locations in 13 patients revealed an MR appearance similar to that of the experimental animal model. Three patients (six thrombi locations) had serial examinations over 4 weeks. No significant change in thrombus signal characteristics was noted with time. It is concluded that MR imaging at 0.35 T cannot be used to predict the age of thrombus (up to 3 weeks) but may be helpful in following its resolution.

Pelvic masses in pregnant patients: MR and US imaging.

Sixteen pregnant patients with pelvic masses detected with ultrasound (US) were studied with magnetic resonance (MR) imaging at 0.35 T. Two patients were in their first trimester, eight in the second, and six in the last. On MR images, 34 masses were seen, including 19 uterine leiomyomas. With US, 20 masses were detected. All masses not seen with US were leiomyomas. Only 20 masses (in 11 patients) were removed for histologic study. In nine cases, MR imaging and US provided similar information on the origin, extent, and type of mass. In seven patients, MR imaging contributed additional information. MR imaging depicted more leiomyomas than US in three patients. In another case, MR images showed that a mass depicted with US was actually a loop of bowel. MR images allowed differentiation between a solid soft-tissue mass and a hemorrhagic fluid-containing mass, correctly depicted the presence of an abdominal pregnancy, and allowed evaluation of the parametrium for spread of cervical carcinoma.

Local area networks in an imaging environment.

There is great interest at present in incorporating image-management systems popularly referred to as picture archiving and communication systems (PACS) into imaging departments. This paper will describe various aspects of local area networks (LANs) for medical images and will give a definition of terms and classification of devices by describing a possible system which links various digital image sources through a high-speed data link and a common image format, allows for viewing and processing of all images produced within the complex, and eliminates the transport of films. The status of standards governing LAN and particularly PACS systems along with a proposed image exchange format will be given. Prototype systems, particularly a system for nuclear medicine images, will be presented, as well as the prospects for the immediate future in terms of installations started and commercial products available. A survey of the many questions that arise in the development of a PACS for medical images and also a survey of the presently suggested/adopted answers will be given.

Modus operandi for a picture archiving and communication system.

The authors describe their 18 month experience operating an all digital nuclear medicine department, which led to the development of a system that allows multiple users to access patient reports and images through terminals located in various parts of the hospital. All user interactions are mediated through protocols that automatically acquire, process, display, and archive data. This approach offers distinct advantages over film and paper methods and is applicable in theory to any digital image format.