Optical biopsy and imaging using optical coherence tomography.

Optical coherence tomography is a new imaging technique that can perform high-resolution, micrometre-scale, cross-sectional imaging in biological systems. The technology has been developed, and reduced to, preliminary clinical practice in ophthalmology. The challenging problem that OCT may address is the development of 'optical biopsy' techniques. These techniques can provide diagnostic imaging of tissue morphology without the need for excision of specimens. Many investigations remain to identify optimal areas for clinical application, and additional engineering must be done to integrate vertically the technology and to reduce it to clinical practice. Nevertheless, preliminary studies indicate the feasibility of developing this technology for a wide range of clinical and research diagnostic imaging applications. The ability to non-excisionally evaluate tissue morphology using a catheter or an endoscope could have a significant impact on the diagnosis and management of a wide range of diseases.

In vivo endoscopic optical biopsy with optical coherence tomography.

Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

"Borderline" myocarditis: an indication for repeat endomyocardial biopsy.

Repeat endomyocardial biopsy was performed in 28 patients with dilated cardiomyopathy of less than or equal to 12 months' duration and either symptomatic heart failure or life-threatening ventricular arrhythmias. Myocarditis was strongly suspected clinically in all cases, yet was unconfirmed on initial right ventricular biopsy. Seventeen patients underwent both right and left ventricular biopsy, seven patients had a repeat right ventricular biopsy and four patients underwent repeat left ventricular biopsy alone. The interval between initial and repeat biopsy averaged 31 +/- 6 days. Myocarditis was confirmed on repeat biopsy in 4 of 6 patients whose initial biopsy revealed "borderline" myocarditis (that is, interstitial inflammation but absence of myocyte necrosis) compared with none of the 22 patients whose initial biopsy showed either myocyte hypertrophy or interstitial fibrosis, or both (p = 0.0007). "Borderline" myocarditis on initial biopsy was the only clinical or histologic finding predictive of myocarditis on subsequent biopsy. Repeat endomyocardial biopsy can identify and potentially modify the treatment of an additional group of patients with dilated cardiomyopathy and nondiagnostic initial endomyocardial histologic features. Right ventricular sampling should be repeated in patients whose initial biopsy demonstrates "borderline" myocarditis.

Intercellular adhesion molecule-1 induction: a sensitive and quantitative marker for cardiac allograft rejection.

OBJECTIVES: Rats with abdominal heterotopic heart transplants were studied to determine whether cardiac allograft rejection could be assessed by immunoscintigraphy targeting intercellular adhesion molecule-1 (ICAM-1), which was induced on allografted organ cells in association with rejection. BACKGROUND: It is important to detect early rejection before development of myocyte necrosis. Although a variety of methods for the detection of cardiac rejection have been investigated, histologic inspection of biopsied samples is still used routinely for clinical diagnosis of rejection. METHODS: DA rat (RT-1a) hearts were transplanted into PVG rats (RT-1c). Immunohistologic examination of the allografts demonstrated that ICAM-1 induction on vascular endothelial cells was observed as early as 4 days after transplantation in this combination. Thirty-nine allografted rats and seven isografted rats were studied. One day after injection of 100 microCi of 111Inlabeled anti-ICAM-1 monoclonal antibody (1A29), planar images were obtained. RESULTS: Rejecting allografts showed increased radiotracer uptake and could be identified on the images as early as 5 days after transplantation. In contrast, nonrejecting cardiac allografts and isografts did not show specific uptake. Mildly rejecting allografts, with mononuclear cell infiltration but without significant myocyte necrosis, could be scintigraphically identified, and the level of radiotracer uptake reflected the histologic severity of rejection. Accumulation of 111In-labeled monoclonal antibody of isotype-matched irrelevant specificity was not detected in the rejecting allografts. CONCLUSIONS: These data indicate that ICAM-1 induction can be assessed quantitatively by radioimmunoscintigraphy. Radioimmunoscitigraphy is a sensitive method for early detection and assessment of cardiac allograft rejection.

Doppler color flow mapping of epicardial coronary arteries: initial observations.

OBJECTIVES: We addressed the hypothesis that blood flow could be imaged by Doppler color flow mapping of the coronary arteries and characteristic patterns described in normal and diseased vessels. BACKGROUND: Echocardiographic imaging of the epicardial coronary arteries has been suggested as a useful adjunct to their intraoperative evaluation. Addition of Doppler color flow mapping could potentially enhance this evaluation by displaying the flow disturbance produced by anatomic lesions whose physiologic significance may otherwise be uncertain. In experimental models, such displays could also potentially provide insights into the pathophysiology of coronary blood flow and stenosis. METHODS: Epicardial coronary arteries were examined with a high resolution 7-MHz linear phased-array transducer both in vivo and in vitro. 1) The coronary arteries were studied in the beating hearts of 10 open chest dogs in which experimental stenoses were also created; the maximal extent of the arterial tree in which flow could be seen in the most ideal setting was also examined in four additional excised perfused canine hearts. 2) Six excised human coronary arteries were perfused in a pulsatile manner to determine whether abnormal flow patterns could be prospectively identified and subsequently correlated with pathologic evidence of stenosis. RESULTS: All normal coronary artery segments studied showed homogeneous flow without evidence of flow disturbance. In the excised heart, flow could be visualized to the distal extent of the epicardial vessels; in the open chest model, visualization of the proximal 5 to 6 cm was comparable, although surrounding structures limited access to the terminal portions of the vessels. The stenotic lesions created in the canine hearts (n = 9) showed recognizable alterations in the flow pattern: localized aliasing, proximal blood flow acceleration, distal flow disturbance and recirculatory flow. In the excised human arteries, these features identified 12 lesions, all of which corresponded to areas of > or = 50% lumen narrowing by pathologic examination. CONCLUSION: Blood flow in the epicardial coronary arteries can be imaged by Doppler color flow mapping and characteristic flow patterns described in normal and diseased vessels.

Effects of prolonged transesophageal echocardiographic imaging and probe manipulation on the esophagus--an echocardiographic-pathologic study.

Transesophageal echocardiography is being increasingly utilized in the operating room and intensive care and ambulatory settings. However, to date no data are available concerning possible trauma of the transesophageal echocardiographic technique to the esophagus due to probe insertion, manipulation or direct ultrasound energy transmission. To test the hypothesis that transesophageal manipulations caused no traumatic or thermal injury to the esophageal mucosa, 12 animals were studied with continuous transesophageal echocardiography for a period of variable duration (mean 4.6 h +/- 51 min). The study group consisted of four monkeys (mean weight 5.7 +/- 0.6 kg and eight mongrel dogs (mean weight 29.8 +/- 1.4 kg). The eight dogs were studied during right heart bypass with full heparinization for 6.6 +/- 0.2 h, whereas the four monkeys were studied for 60 to 90 min in the absence of cardiopulmonary bypass and anticoagulation. Immediately after completion of transesophageal echocardiography in each case, the esophagus was entirely excised. Detailed macroscopic and microscopic examination of the esophagus revealed no significant mucosal or thermal injury. This preliminary animal study suggests that transesophageal echocardiography is safe for the esophageal mucosa in animals as small as 5 kg in weight, despite prolonged use and in the presence of systemic anticoagulation.

Lymphoid infiltrates of the stomach. Evaluation of histologic criteria for the diagnosis of low-grade gastric lymphoma on endoscopic biopsy specimens.

Low-grade gastric lymphomas may be difficult to distinguish from benign inflammatory infiltrates on endoscopic biopsy specimens. Recent reports have suggested that so-called lymphoepithelial lesions (infiltration of lymphocytes into glandular epithelium) are characteristic of primary gastric lymphomas. We evaluated the presence and prominence of lymphoepithelial lesions and other histologic criteria in 25 low-grade gastric lymphomas (21 primary) and 58 benign inflammatory infiltrates to evaluate their utility in distinguishing benign from malignant gastric lymphoid infiltrates. The following features were associated only with lymphomas: (a) prominent (2-3 +) lymphoepithelial lesions (eight of 24 versus none of 58; p less than .0001); (b) Dutcher bodies (three of 25 versus none of 58, p = .05); and (c) moderate cytologic atypia (nine of 25 versus none of 58, p less than .0001). One or more of these features was seen in 18 of 25 gastric lymphomas (72%). Features more often associated with, but not limited to, lymphomas were dense (2-3 +) lymphoid infiltrates (25 of 25 versus five of 58, p less than .0001), rare or questionable lymphoepithelial lesions (11 of 24 versus 17 of 58, p = .01), muscularis mucosae invasion (20 of 20 versus 20 of 47, p less than .0001), ulceration (12 of 24 versus five of 58, p less than .0001), and mild cytologic atypia (eight of 25 versus six of 58, p less than .005). Germinal centers, crypt abscesses, and reactive epithelial atypia were seen with equal frequency in both types of infiltrate. Acute inflammation (2-3 +) was associated more often with inflammatory infiltrates (two of 25 versus 27 of 58, p less than .001). Our results suggest that dense lymphoid infiltrates with either prominent lymphoepithelial lesions, moderate cytologic atypia, or Dutcher bodies are highly suggestive and may be diagnostic of lymphoma. This constellation of findings is present in about 70% of endoscopic biopsy specimens of low-grade gastric lymphoma. In addition, the majority of cases of primary low-grade gastric lymphoma have morphologic, immunophenotypic, and clinical features that justify their inclusion in the category of low-grade lymphomas of mucosa-associated lymphoid tissue, whereas a minority are examples of lymphomatous polyposis of the gastrointestinal tract (centrocytic lymphoma).

Evaluation of myocardial infarct size before and after reperfusion: dual-tracer imaging with radiolabeled antimyosin antibody.

UNLABELLED: Antimyosin antibody is a specific marker of myocardial necrosis that is based on the loss of integrity of the sarcolemmal membrane. Because antimyosin can be labeled with several different radiotracers, gamma imaging performed with antimyosin labeled with two different radionuclides can be used to quantify infarct size before and after an intervention such as reperfusion. METHODS: Twelve open-chested anesthetized dogs were evaluated both at the end of 1.5 hr of occlusion of the left anterior descending coronary artery and following reperfusion. Antimyosin Fab radiolabeled with either 123I or 111In was injected by intracoronary administration over 3 min at the end of the occlusion interval, and the coronary sinus was drained continuously for 7 min to prevent recirculation of the antibody. One hour after reperfusion, a second injection of antimyosin Fab (labeled with a different isotope from the first) was administered as before. Six dogs were given intracoronary trifluoperazine (150 micrograms/kg of body weight) simultaneously with reperfusion, and another six dogs received saline as the control. The infarct size in grams before and after reperfusion was assessed by antimyosin antibody uptake in ex vivo images of 1-cm thick slices of the hearts. The mean infarct sizes before (W1) and after (W2) reperfusion were then calculated as the percent of infarcted myocardium/ventricular myocardial mass. RESULTS: There was a significant increase in the mean percent infarct size after reperfusion in the control group (W2 = 16.73 +/- 4.0, W1 = 14.92 +/- 3.88; p = 0.029). The mean infarct size was uniformly smaller with trifluoperazine intervention (W2 = 12.33 +/- 2.03, W1 = 16.34 +/- 2.78; p = 0.004). The difference between the mean change in the infarct sizes in the two groups was highly significant (p = 0.002). CONCLUSION: Dual imaging of the extent of myocardial necrosis before and after an intervention (reperfusion) in the same animal demonstrated the utility of antimyosin imaging to document changes in the extent of necrosis.

Imaging of coronary artery microstructure (in vitro) with optical coherence tomography.

OCT achieves high-resolution and image differentiation of vascular tissues to a degree that has not been previously possible with any method except excisional biopsy. Thus, OCT represents a promising new diagnostic technology for intracoronary imaging, which could permit the in vivo evaluation of critical vascular pathology.

Usefulness of antimyosin antibody imaging for the detection of active rheumatic myocarditis.

Myocarditis constitutes an important component of rheumatic carditis. Antimyosin scintigraphy, which allows noninvasive assessment of myocyte damage, can be used for documentation of cardiac involvement in patients with rheumatic fever where clinical diagnosis is not unequivocal.

Aortoesophageal fistula arising as a complication of prolonged nasogastric tube placement.

Aortoesophageal fistula is a rare disorder that may result from many causes. In this report, we describe the unique case of a 71-year-old woman who developed an aortoesophageal fistula following prolonged placement of a nasogastric tube. The presence of dense fibrous adhesions between the aorta and esophagus may have facilitated the development of aortoesophageal fistula in this patient.

Variability in cyst fluid carcinoembryonic antigen level, fluid viscosity, amylase content, and cytologic findings among multiple loculi of a pancreatic mucinous cystic neoplasm.

The procedure of percutaneous aspiration and analysis of cyst contents has been advocated to provide a preoperative diagnosis of pancreatic cystic lesions (pseudocysts and cystic tumors), but it is not known whether variation in the contents of separate loculi of a multilocular neoplasm might misrepresent the identity of the tumor. The authors measured the cyst fluid carcinoembryonic antigen (CEA) level, fluid viscosity, and amylase content and performed cytologic analysis on aspirates rates from ten different loculi of a single mucinous cystic neoplasm of the pancreas. The CEA levels were highly variable (median, 6,326 ng/mL; range, 962-64,670 ng/mL) but in all cases were diagnostic of a mucinous tumor. Fluid relative viscosity values were also variable (median, 2.4; range, 1.3-10+) but diagnostic in eight of nine aspirates. The amylase content in all of the loculi was low (< 91 U/L), and values were consistent with a cystic tumor. Cytologic analysis showed diagnostic mucin-secreting epithelial cells in nine of ten loculi. Although cytologic examination was nondiagnostic in one loculus, there were no false-positive results for malignancy. The combination of all four tests would not have resulted in misclassification of any of the tumors. The authors conclude that the characteristics of the contents of different loculi of pancreatic cystic neoplasms may be variable, but the use of a combination of tests still ensures accurate diagnosis.

Cyst fluid cytologic analysis in the differential diagnosis of pancreatic cystic lesions.

Pancreatic cystic lesions include inflammatory pseudocysts, benign serous cystadenomas, and mucinous neoplasms, some of which are malignant. Cytologic analysis of cyst fluid has been proposed to diagnose pancreatic cysts before definitive therapy. The authors report an analysis of 31 pancreatic cyst aspirates: 9 pseudocysts, 5 serous cystadenomas, 8 mucinous cystic neoplasms, 4 mucinous cystadenocarcinomas, 2 papillary cystadenocarcinomas, 1 mucinous ductal adenocarcinoma with cystic degeneration, and 2 cystic islet cell tumors. All pseudocysts were correctly classified as probable inflammatory lesions, because of the presence of abundant acute inflammation and histiocytes and the absence of glandular epithelium. Three of five serous cystadenomas were correctly classified, based on the presence of small cuboidal cells in clusters with microvesicular cytoplasm containing glycogen. Eleven of 12 mucinous tumors contained round cells with large cytoplasmic mucin vacuoles or columnar cells containing cytoplasmic mucin. Malignancy was diagnosed in 5 of 7 carcinomas, 1 case was classified as suspicious for malignancy, and 1 case was nondiagnostic because of the absence of a cellular component. The authors concluded that pancreatic cyst fluid cytologic analysis is useful in differentiating mucinous from nonmucinous pancreatic cysts and may provide definitive evidence of malignancy. In some cases, serous cystadenoma can be diagnosed based on cytologic analysis. An inflammatory smear without epithelial cells suggests a pseudocyst, but these findings are nonspecific, as a similar pattern may occur when a cystic neoplasm undergoes degenerative changes. Therefore, pseudocyst remains a diagnosis of exclusion.

Optical biopsy with optical coherence tomography.

A need exists in medicine for a technology capable of 'optical biopsy,' imaging at or near the resolution of histopathology without the need for excisional biopsy. Optical coherence tomography (OCT) is a recently developed imaging technology that uses infrared light to generate cross-sectional images on a micron scale. In this work, the feasibility of OCT for optical biopsy was confirmed with in vitro tissue from the skeletal and male reproductive systems. This work supports the hypothesis that OCT is an attractive technology for in vivo optical biopsy.

New technology for high-speed and high-resolution optical coherence tomography.

Optical coherence tomography (OCT) is an optical imaging technique that is capable of performing micron-scale, cross-sectional imaging of internal microstructure in biological systems. OCT is analogous to ultrasound B mode imaging except that it uses light rather than sound and performs imaging by measuring the back-scattered intensity of light from structures in tissue. We describe recent advances in OCT technology including the application of short pulse solid state lasers based on Ti: Al2O3 and Cr: Mg2SiO4 to enable high-resolution, high-speed imaging as well as the development of OCT catheter/endoscope delivery to permit imaging of internal organ systems. OCT enables the nonexcisional, in situ, real-time imaging of tissue microstructure and is thus a powerful and promising technique for optical biopsy.

Expression of CA 15.3 protein in the cyst contents distinguishes benign from malignant pancreatic mucinous cystic neoplasms.

BACKGROUND: Inflammatory pseudocysts, serous cystadenomas, and mucinous cystic tumors comprise most cystic lesions of the pancreas. The mucinous tumors include mucinous cystic neoplasms, which are benign on histologic examination but have the potential for malignant transformation, and mucinous cystadenocarcinomas. Accurate preoperative classification of pancreatic cysts with clinical and radiologic criteria is often impossible, and as a result many cystic tumors are inappropriately treated as pseudocysts. Analysis of percutaneous needle-aspirated cyst fluid for tumor markers, enzymes, viscosity, and cytologic study has been proposed as a useful modality to distinguish mucinous from nonmucinous cystic lesions. However, no reliable cyst fluid parameter distinguishes benign from malignant mucinous tumors. METHODS: The concentration of the tumor marker CA 15-3 was measured by immunoassay in cyst fluid from six pseudocysts, five serous cystadenomas, three mucinous cystic neoplasms, and six mucinous cystadenocarcinomas. RESULTS: The concentration of CA 15-3 in the cyst fluid of mucinous cystadenocarcinomas was higher (mean, 178 units/ml; range, 40 to 392) than that of mucinous cystic neoplasms (mean, 4.7 units/ml; range, 0 to 14), serous cystadenomas (mean, 9.2 units/ml; range, 0 to 32), and pseudocysts (mean, 15.3 units/ml; range, 0 to 66). An upper cutoff value of 30 units/ml distinguished mucinous cystic neoplasms from mucinous cystadenocarcinomas with 100% sensitivity and 100% specificity (p = 0.01). CONCLUSIONS: Production of CA 15-3 appears to coincide with malignant transformation in pancreatic mucinous cystic neoplasms. We conclude that measurement of CA 15-3 levels in the cyst fluid is useful in the differentiation of benign from malignant pancreatic mucinous cysts.

Relation of epidermal growth factor receptor and estrogen receptor-independent pS2 protein to the malignant transformation of mucinous cystic neoplasms of the pancreas.

OBJECTIVE: To evaluate the role of epidermal growth factor receptor (EGF-R) and pS2 protein in the evolution of malignancy in mucinous cystic tumors of the pancreas. BACKGROUND: Mucinous cystic tumors of the pancreas include histologically benign but premalignant mucinous cystic neoplasms and mucinous cystadenocarcinoma. The molecular events leading to transformation from a benign to a malignant mucinous tumor are not known. Overexpression of EGF-R and detection of an estrogen-induced protein (pS2) has been demonstrated in ductal adenocarcinomas of the pancreas, but these factors have not been evaluated in mucinous cystic tumors. DESIGN: Twenty-six mucinous tumors were examined for EGF-R, pS2 protein, and estrogen and progesterone receptors. RESULTS: Eight (61.2%) of 13 malignant tumors exhibited increased expression of EGF-R, whereas EGF-R was not detected in any of the 13 benign tumors (P = .002). The pS2 protein was detected in nine of 11 malignant and 11 of 11 benign tumors (P = .480). Estrogen and progesterone receptors were not detected in the epithelium of either tumor type. The median survival time of the patients with EGF-R-negative tumors was 29.0 months compared with 14.5 months for those with EGF-R-positive tumors, but this difference did not reach significance owing to the small population size. CONCLUSIONS: Overexpression of EGF-R in mucinous cystic tumors, as in ductal adenocarcinomas, may be an important feature associated with malignancy and may have prognostic significance. Failure to detect EGF-R in histologically benign epithelium suggests that the upregulation of EGF-R may be important in the evolution of aggressive behavior. The expression of pS2 protein appears to be independent of estrogen and may play a role in the proliferative activity of mucinous tumors. However, pS2 expression is not a feature associated exclusively with malignancy.

Cyst fluid NB/70K concentration and leukocyte esterase: two new markers for differentiating pancreatic serous tumors from pseudocysts.

Cystic lesions of the pancreas include inflammatory pseudocysts, serous cystadenomas, and mucinous tumors, some of which are malignant. Preoperative clinical and radiological parameters are unreliable and may result in incorrect diagnosis and inappropriate treatment. Cyst fluid analysis for cytology, viscosity, carcino-embryonic antigen, CA 72-4, and CA 15-3 will distinguish mucinous from nonmucinous lesions and usually help in determining malignancy. Currently, there is no reliable method to differentiate inflammatory pseudocysts from serous cystadenomas. This distinction is important because the treatment of these two lesions is different; pseudocysts are either observed or drained, whereas serous tumors are usually resected. The tumor marker NB/70K was measured in aspirated cyst fluid from 13 inflammatory pseudocysts and 11 serous cystadenomas by a commercial immunoassay. Leukocyte esterase was measured using Chemstrip SG urine test strips and amylase and lipase on a routine chemistry analyzer. The cyst fluid NB/70K concentration was significantly higher in pseudocysts (mean, 555 U/ml; range, 42-1,926 U/ml) than in serous cystadenomas (mean, 12 U/ml; range 0-130 U/ml) and this difference was significant (p < 0.0002). Leukocyte esterase was detected in 7 of 11 pseudocysts but was absent in 10 of 10 serous tumors (p = 0.002). Amylase and lipase values were generally higher in pseudocysts but these markers were unreliable due to marked outliers. Cyst fluid NB/70K and leukocyte esterase are promising markers to help differentiate pseudocysts from serous tumors on percutaneous aspirates. When combined with previously reported cyst fluid parameters (amylase, lipase, cytology, and amylase isoenzymes), these two cystic lesions can be reliably distinguished.

Two- and three-dimensional high-resolution imaging of the human oviduct with optical coherence tomography.

OBJECTIVE: To evaluate the feasibility of optical coherence tomography, a new method of micron-scale imaging, for high-resolution assessment of the oviduct. Optical coherence tomography is analogous to ultrasound except that it measures the backreflection of infrared light rather than acoustical waves. DESIGN: The ampulla of a human fallopian tube was imaged in vitro using optical coherence tomography. Images were generated in 2 and 3 dimensions. SETTING: University. PATIENT(S): Samples were obtained from women who had undergone hysterectomy for leiomyomatosis. INTERVENTION(S): None MAIN OUTCOME MEASURE(S): The ability to perform imaging on a micron scale, which is a level of resolution higher than that of any currently available clinical technology. RESULT(S): Two- and three-dimensional data sets of the reflectance of a human fallopian tube were acquired. A volume of 5 x 5 x 2.5 mm (length x width x depth) was scanned. The axial resolution was 11 microm, and the lateral resolution at the focus was 20 microm. The data sets showed detailed structures of the fallopian tube. CONCLUSION(S): Our ability to obtain micron-scale two- and three-dimensional images of an in vitro oviduct suggests that it may be possible to identify and surgically treat tubal causes of infertility.