A native chemical chaperone in the human eye lens

Cataract is one of the most prevalent protein aggregation disorders and still the most common cause of vision loss worldwide. The metabolically quiescent core region of the human lens lacks cellular or protein turnover; it has therefore evolved remarkable mechanisms to resist light-scattering protein aggregation for a lifetime. We now report that one such mechanism involves an unusually abundant lens metabolite, myo-inositol, suppressing aggregation of lens crystallins. We quantified aggregation suppression using our previously well-characterized in vitro aggregation assays of oxidation-mimicking human γD-crystallin variants and investigated myo-inositol’s molecular mechanism of action using solution NMR, negative-stain TEM, differential scanning fluorometry, thermal scanning Raman spectroscopy, turbidimetry in redox buffers, and free thiol quantitation. Unlike many known chemical chaperones, myo-inositol’s primary target was not the native, unfolded, or final aggregated states of the protein; rather, we propose that it was the rate-limiting bimolecular step on the aggregation pathway. Given recent metabolomic evidence that it is severely depleted in human cataractous lenses compared to age-matched controls, we suggest that maintaining or restoring healthy levels of myo-inositol in the lens may be a simple, safe, and globally accessible strategy to prevent or delay lens opacification due to age-onset cataract.

Serial positron emission tomography scans following radiation therapy of patients with head and neck cancer

BACKGROUND

A single institution study was undertaken to evaluate the role of positron emission tomography (PET) scans with fluorodeoxyglucose (FDG) prior to radiation and following radiation.

METHODS

Forty-five patients with head and neck cancers were evaluated with FDG-PET scans as well as either CT or MRI prior to treatment with definitive radiation (RT). These same scans were obtained following completion of RT at 1 month (36 patients), 4 months (28 patients), 12 months (19 patients), and 24 months (15 patients). Standard uptake values (SUV) normalized for blood glucose and lean body mass were calculated on the initial and 1-month post-treatment PET scans.

RESULTS

Fifteen patients are alive without evidence of disease at 24 to 52 months following RT. Initial SUVs were calculated on the primary tumor site and ranged from 2.5 to 28.5. These values did not have any correlation with local control when examined for the entire group, primary site, or T stage. One-month post-RT SUV ranged from 1.8 to 6.24. Of the 36 1-month post-RT PET scans, six were interpreted as positive for residual disease and were confirmed by biopsy. Four of the five scans, which were interpreted as equivocal, were positive on biopsy. Seven of the 25 scans, which were interpreted as negative for tumor, were positive on biopsy. Four-month scans were more accurate for disease with disease noted in 0 of 18 negative scans, 6 of 7 positive scans, and 2 of 3 equivocal scans.

CONCLUSIONS

PET is useful for initial imaging of head and neck cancers. SUV does not appear to be useful for predicting outcome following treatment with RT. One-month post-RT scans were inaccurate for predicting the presence of cancer. Four-month post-RT scans were a better predictor for the presence of cancer.

Complications of renal transplantation: evaluation with US and radionuclide imaging

Following renal transplantation, patients are often evaluated with ultrasonography (US) or radionuclide imaging to assess renal function and the presence of possible complications. Both modalities are inexpensive, noninvasive, and nonnephrotoxic. A basic understanding of the surgical techniques commonly used for renal transplantation is useful when imaging these patients in order to recognize complications and to direct further imaging or intervention. The most frequent complications of renal transplantation include perinephric fluid collections; decreased renal function; and abnormalities of the vasculature, collecting system, and renal parenchyma. Perinephric fluid collections are common following transplantation, and their clinical significance depends on the type, location, size, and growth of the fluid collection, features that are well-evaluated with US. Causes of diminished renal function include acute tubular necrosis, rejection, and toxicity from medications. Radionuclide imaging is the most useful modality for assessing renal function. Vascular complications of transplantation include occlusion or stenosis of the arterial or venous supply, arteriovenous fistulas, and pseudoaneurysms. Although the standard for evaluating these vascular complications is angiography, US is an excellent noninvasive method for screening. Other transplant complications such as abnormalities of the collecting system and renal parenchyma are well-evaluated with both radionuclide imaging and US.

FDG PET evaluation of head and neck cancer: value of imaging the thorax

BACKGROUND

Patients with primary tumors of the head and neck have been reported to have a high rate of synchronous primary tumors of the upper aerodigestive tract. This study was performed to determine whether inclusion of the thorax in the scan volume would be diagnostically useful for positron emission tomography (PET) with [F-18] fluorodeoxy-D-glucose (FDG) in patients with primary tumors of the head and neck.

METHODS

FDG PET scans from the midcranium to the diaphragm were obtained on 56 patients with a variety of head and neck tumors on initial examination before definitive therapy. PET findings in the chest were correlated with results of all other imaging studies, biopsy results, and clinical follow-up.

RESULTS

In nine studies (16%), areas of increased FDG uptake in the chest were seen and were judged to be tumors. Six of these probably were false-positive results, although one of these six may have been unconfirmed true positives. Of the three confirmed true-positive studies, two were obvious from other routine studies. In only one case did the PET study reveal a significant lesion not found by means of routine evaluation, resulting in a case-finding yield of 2%. If the unconfirmed possible true-positive results are included, the case-finding yield increases to 4%.

CONCLUSIONS

No compelling indication was seen for including the chest in PET studies of patients with head and neck cancer.

De-N-acetyl-gangliosides in humans: unusual subcellular distribution of a novel tumor antigen

The disialoganglioside GD3 is a major antigen in human melanomas that can undergo 9-O-acetylation of the outer sialic acid (giving 9-OAc-GD3). Monoclonal antibody SGR37 detects a different modification of the GD3, de-N-acetylation of the 5-N-acetyl group (giving de-N-Ac-GD3). We found that conventional immunohistochemistry of the SGR37 antigen is limited by a reduction in reactivity upon fixation with aldehydes (which presumably react with the free amino group) or with organic reagents (which can extract glycolipids). We optimized conditions for detection of this antigen in unfixed frozen tissue sections and studied its distribution in human tissues and tumors. It is expressed at low levels in a few blood vessels, infiltrating mononuclear cells in the skin and colon, and at moderate levels in skin melanocytes. In contrast, the antigen accumulates at high levels in many melanomas and in some lymphomas but not in carcinomas. In positive melanomas, expression is sometimes more intense and widespread than that of GD3. Both 9-O-acetylation and de-N-acetylation of GD3 seem to occur after its initial biosynthesis. Isotype-matched antibodies against GD3, 9-O-acetyl-GD3 and de-N-acetyl-GD3 were used to compare their subcellular localization and trafficking. 9-O-acetyl-GD3 colocalizes with GD3 predominantly on the cell surface and partly in lysosomal compartments. In contrast, de-N-acetyl-GD3 has a diffuse intracellular location. Adsorptive endocytosis of antibodies indicates that whereas GD3 remains predominantly on the cell surface, de-N-acetyl-GD3 is efficiently internalized into a compartment that is distinct from lysosomes. Rounding up of melanoma cells occurring during growth in culture is associated with relocation of the internal pool of de-N-acetyl-GD3 to the cell surface. Thus, a minor modification of the polar head group of a tumor-associated glycosphingolipid can markedly affect the subcellular localization and trafficking of the whole molecule. The high levels of the SGR37 antigen in melanomas and lymphomas, its selective endocytosis from the cell surface, and its relocation to the cell surface of rounded up cells suggest potential uses in diagnostic or therapeutic approaches to these diseases.

Transcutaneous renal function monitor: precision during unsteady hemodynamics

OBJECTIVE

Hospital acquired renal dysfunction, most commonly caused by renal hypoperfusion, dramatically increases mortality in intensive care patients. Glomerular filtration rate (GFR) is rapidly altered during renal hypoperfusion, and a more rapid means of GFR measurement may prompt institution of renal-specific therapy. We hypothesized that a transcutaneous renal function monitor can rapidly and accurately assess acute changes in GFR within a time frame much shorter than the 2-4 hours currently available.

METHODS

The study design was a prospective determination of the capability to measure GFR transcutaneously. In three different studies, concurrent transcutaneous measurement of GFR, using the rate of disappearance of 99mTc-diethylenetriaminepentaacetic acid (DTPA), was compared by correlation and standard deviation (SD) to reference standards of DTPA plasma clearance, serum inulin clearance, or serum creatinine.

RESULTS

Continuous transcutaneous clearance (TC) measurement correlated with standard DTPA plasma clearance techniques (r = 0.93). Acute pharmacologically induced changes in GFR are detectable by TC measurement within 12-20 min, a time interval significantly affected by the data acquisition interval. Excess patient movement in the ICU patients created clearance artifacts in 50% of clearance traces. Retrospective analysis of ICU patient data reveal TC measurements are 93% specific and 92% sensitive for serum creatinine levels in critically ill patients.

CONCLUSIONS

TC monitoring provides prompt indication of directional changes in GFR and may provide the clinician warning of inadequate resuscitation. Prospective analysis of the specificity, sensitivity, and TC guided renal-specific resuscitation is needed.

FDG PET in head and neck cancer

In our extensive experience with FDG PET imaging in head and neck cancer, we have found the technique to be of high accuracy but of limited usefulness. This seeming paradox arises from several causes. Competing techniques such as CT, MR imaging, and even clinical examination already have good accuracy. In addition, high-resolution studies such as CT and MR imaging provide information required for treatment planning that is unavailable from FDG PET images. The high cost of FDG PET militates against its use in this setting, in which only a small marginal gain can be expected. In the special problem areas in which FDG PET might be expected to offer unique advantages, such as screening for second primary lesions, searching for unknown primary lesions, or differentiating benign salivary rumors from malignant lesions, the results of FDG PET have been disappointedly poor. Of these special problem areas, only the question of accuracy in finding occult primary lesions appears unresolved and in need of further study. The single application in which FDG PET appears to be advantageous is the posttherapy setting. In this setting, the technique is definitely superior to alternative methods of determining tumor recurrence and differentiating posttherapy sequelae such as radiation necrosis from tumor recurrence. We believe that considerable opportunity remains for further research on the use of FDG PET in head and neck cancer. Other agents such as 11C-methionine for example, might improve the diagnostic accuracy of FDG PET in some of the problem areas that we have identified, such as the early postirradiation period. We currently have such a study under way. Also, because FDG PET offers a unique way to measure tumor metabolism, further investigation of the use of FDG PET tracers to evaluate various biologic parameters such as proliferation rates or tumor hypoxia are needed. Such studies could provide a noninvasive technique to identify which fractionation schemes or combinations of therapy might be useful for individual patients. A final caveat is in order. Although our findings of the usefulness (and lack thereof) of FDG PET in head and neck cancer may be disappointing to many, these results should not be generalized to other applications of FDG PET in oncology. Each tumor type and setting presents its own specific problems, and in some instances FDG PET offers unique advantages over other imaging techniques. A good example is the setting of primary lung cancer, in which FDG PET appears clearly superior to all other methods of pretherapy screening [19-20].

Prospective evaluation of selective lymph node biopsy for cutaneous malignant melanoma

Some patients presenting with cutaneous malignant melanoma without palpable adenopathy have regional metastatic disease. We have applied the technique of gamma probe-directed selective lymph node biopsy and used the results to direct further therapy. The results of a prospective nonrandomized clinical study are presented. Between November 1993 and December 1996, 63 patients with a diagnosis of primary cutaneous malignant melanoma underwent lymphoscintigraphy with technetium sulfur colloid followed by gamma probe-guided lymph node biopsy. There were 32 (51%) women and 31 (49%) men with a mean age of 51.1 years (median, 50; range, 13-87). Mean Breslow thickness was 2.13 mm (range, 0.5-15.0 mm; median, 1.56 mm). Primary locations were head and neck in 8 (13%), trunk in 24 (38%), upper extremity in 13 (21%), and lower extremity in 18 (29%). Selective lymph node biopsy was done on an outpatient basis with local anesthesia in 49 cases (78%) and in the operating room with general anesthetic in 14 patients (22%). One lymph node site was biopsied in 46 patients (73%), two sites in 16 (25%), and three in 1 (2%), for a total of 81 selective lymph node biopsy sites, mean 1.29 per patient. The mean number of labeled lymph nodes removed per site per patient was 1.64 (range, 1-5). Seroma or infection occurred in 6 patients (10%). Micrometastatic disease was identified in nine selective lymph node biopsy sites in eight patients. Of eight patients undergoing lymph node dissection, 5 (63%) had no additional pathological lymph node involvement. With a mean follow-up of 579 days from selective lymph node biopsy (median, 594; range, 36-1157), 59 (94%) have no evidence of disease. Three patients have died, 2 with systemic disease (475 and 1149 days) and 1 from a myocardial infarction (380 days). No patient has failed with regional-only recurrence. Gamma probe-directed selective lymph node biopsy is a straightforward procedure that can be done in the outpatient setting and facilitates management of patients with cutaneous malignant melanoma.

Can positron emission tomography distinguish tumor recurrence from irradiation sequelae in patients treated for larynx cancer?

PURPOSE

Distinguishing persistent or recurrent tumor from post-radiation edema or soft-tissue/cartilage necrosis in patients treated for carcinoma of the larynx can be difficult. Because recurrent tumor is often submucosal, multiple deep biopsies may be necessary before a diagnosis can be established. Positron emission tomography with F-18 fluorodeoxyglucose was studied for its ability to aid in this problem.

PATIENTS AND METHODS

FDG PET scans were performed on 31 patients who were suspected of having persistent or recurrent tumor after radiation treatment for carcinoma of the larynx. Patients underwent thorough history and physical examinations, scans with computed tomography (23 patients), and pathological evaluation when indicated. PET scans were interpreted by each of the two radiologists, who were blinded to patient outcome and the other's report.

RESULTS

The time between completion of radiation treatment and positron emission tomography examination ranged from 2 to 61 months with a median of 6 months. Fifteen patients had pathological evidence of tumor in the larynx, while 16 have remained without evidence of disease. The overall sensitivity and specificity of the positron emission tomography interpretations were 80% and 81%, respectively. The sensitivity and specificity of the computed tomography scan interpretations were 58% and 100%, respectively. Of the 23 patients with computed tomography scans, eight patients acquired useful information from the positron emission tomography, three patients had incorrect positron emission tomography interpretations and correct computed tomography interpretations, and one patient had positive tumor despite a negative positron emission tomography and computed tomography.

DISCUSSION

Positron emission tomography is useful in distinguishing benign from malignant changes in the larynx after radiation treatment. This noninvasive technique can supplement information provided by computed tomography scans. It is reasonable to delay biopsy, which could traumatize radiation-damaged tissues and precipitate necrosis, for those patients with negative positron emission tomography scans who have clinical signs and symptoms associated with recurrence.

Cerebral perfusion defects secondary to simple craniosynostosis

Premature fusion of multiple cranial sutures has been associated with increased intracranial pressure and the potential for mental impairment. Isolated craniosynostosis, however, has been thought to be a benign condition primarily reconstructed for aesthetic purposes. On the basis of subjective developmental improvement postoperatively, an objective radiographic analysis (single positron emission computed tomography [SPECT] was used to assess differences in cerebral perfusion in the areas compressed secondary to the fused cranial suture both before and after cranial reconstructive surgery in patients with simple craniosynostosis. Seven children with craniosynostosis, six boys and one girl (age age, 3-28 months), were enrolled in this prospective study. Six of the seven had cranial asymmetry on preoperative cranial computed tomographic scans, and one had a symmetric defect and was used as a control. Each subject had a preoperative SPECT scan approximately 3 to 5 days before the cranial reconstruction procedure and a follow-up scan 6 to 10 weeks postoperatively. Preoperative asymmetries in cerebral perfusion ranged from 0 to 30% (mean, 13%) the areas compressed secondary to the premature suture fusion. In five patients cerebral blood flow, which was asymmetric before surgery, became symmetric after craniofacial reconstruction, and no new perfusion defects were documented. The control patient and one another patient had symmetric perfusion both pre- and postoperatively. Craniosynostosis may be associated with decreased cerebral blood flow as a result of the constriction of the brain from the prematurely fused suture. The correction of asymmetric cranial single-suture synostosis is more than a cosmetic procedure in that it allows for normalization of cerebral blood flow. This difference in blood flow supports early surgical intervention to prevent any potential central nervous system compromise secondary to abnormal blood flow.

Preoperative identification of benign versus malignant parotid masses: a comparative study including positron emission tomography

Various diagnostic tools were used in 26 patients with parotid masses to determine their value in preoperative malignant or benign categorization. These tools were positron emission tomography (PET), clinical examination, fine-needle aspiration biopsy (FNAB), computed tomography (CT), and magnetic resonance imaging (MRI). PET identified all 26 lesions and all 12 malignant lesions, but made the correct categorization in only 69% of cases. Thus, it was not as good as the more conventional diagnostic methods, their correct categorizations being 85% (clinical), 87% (CT/MRI), and 78% (FNAB) in the same patients.

Positron emission tomography in the evaluation of laryngeal carcinoma

Positron emission tomography (PET) is a relatively new radiologic imaging technique based on glucose analog uptake and metabolism in tumor tissue. In this study, PET was used in evaluating 38 patients with laryngeal cancer. Twenty-five patients were examined with PET prior to treatment to study the reliability of PET in identifying the primary tumor and assessing regional nodal status; 13 patients who had previously received irradiation with curative intent and who represented differential diagnostic problems were imaged to differentiate between irradiation effects and recurrent or residual cancer. Findings for both groups were compared to results of clinical evaluation and those of computed tomography (CT) and magnetic resonance imaging (MRI). The PET results were essentially identical to those of CT, MRI, and clinical evaluation in identifying metastatic lesions (82% correct), and were as reliable as CT and MRI for correctly identifying primary tumors (88%). Positron emission tomography was most helpful in differentiating recurrent tumor from postirradiation tissue sequelae. However, its lack of anatomic detail made PET less valuable for primary staging and therapeutic planning. It may enhance the diagnostic accuracy of CT and MRI where anatomic distortions occur or where diagnostic criteria for CT and MRI are ambiguous.

A comparative diagnostic study of head and neck nodal metastases using positron emission tomography

A prospective study was conducted to compare the accuracy of clinical examination, computed tomography (CT), and positron emission tomography (PET) in identifying head and neck squamous cell carcinoma metastatic to cervical lymph nodes. The findings in the necks of 49 patients evaluated by clinical examination and CT were compared to the findings in the same necks by PET, a newly available metabolic imaging modality. Pathology specimens were available for 45 of the necks. The findings of PET and CT correlated in 84% of cases. In the cases that did not correlate, CT proved correct in four of five cases. PET (82%) and CT (84%) were comparable and were both better than clinical examination (71%) in correctly identifying the presence or absence of metastatic disease.

The effect of varicoceles on testicular blood flow in man

OBJECTIVES

To assess the effect of varicoceles on testicular blood flow in man.

METHODS

Testicular blood flow was measured in 248 consecutive men attending an infertility clinic and 34 fertile volunteers using color duplex ultrasonography.

RESULTS

The testicular blood flow of men with either clinical and/or subclinical varicoceles was not significantly different from controls without varicoceles.

CONCLUSIONS

Varicoceles do not significantly alter testicular blood flow in man.

The effect of varicoceles on testicular blood flow in man

OBJECTIVES

To assess the effect of varicoceles on testicular blood flow in man.

METHODS

Testicular blood flow was measured in 248 consecutive men attending an infertility clinic and 34 fertile volunteers using color duplex ultrasonography.

RESULTS

The testicular blood flow of men with either clinical and/or subclinical varicoceles was not significantly different from controls without varicoceles.

CONCLUSIONS

Varicoceles do not significantly alter testicular blood flow in man.

Positron emission tomography of patients with head and neck carcinoma before and after high dose irradiation

BACKGROUND

Positron emission tomography (PET) with labeled fluorodeoxyglucose (FDG) demonstrates increased tracer uptake in many neoplasms. This study was undertaken to define the patterns of FDG uptake in head and neck neoplasms before and after high dose irradiation.

METHODS

Twenty-five patients were evaluated prospectively with PET and standard clinical and radiographic techniques before and after irradiation.

RESULTS

Twenty-seven primary sites were confirmed pathologically in 23 patients and included the nasopharynx (four lesions), oropharynx (14 lesions), larynx (five lesions), oral cavity (two lesions), and paranasal sinuses (two lesions). Two patients had unknown primary sites. Twenty-four of 27 primary sites correlated with areas of increased tracer uptake on PET scans. Five patients had increased uptake in cervical lymph nodes that were uninvolved by radiographic or clinical criteria. Positron emission tomography seemed to be able to differentiate tumor activity from fluid-filled sinuses in two patients with paranasal sinus tumors. In two patients with unknown primary sites, increased uptake in the base of tongue after PET suggested occult primary sites. Positron emission tomography scans obtained 1 month after high dose irradiation (RT) indicated decreased levels of FDG uptake in all patients' tumors. However, these scans did not accurately reflect the status of disease in these patients. Scans obtained 4 months after RT were believed to assess more accurately the presence of malignancy.

CONCLUSIONS

Positron emission tomography is a new modality that may be useful in defining tumor activity in clinically negative areas. Appropriately timed posttreatment PET may be useful in predicting outcome after definitive RT and in distinguishing viable tumors from normal tissue changes after RT in patients with head and neck carcinomas.

Salivary gland tumors: pretherapy evaluation with PET

PURPOSE

To determine whether positron emission tomography (PET) can help differentiate benign from malignant lesions of the salivary glands before surgery.

MATERIALS AND METHODS

Masses of the salivary glands were examined in 26 patients by means of computed tomography, magnetic resonance imaging, PET, biopsy (n = 18), and surgery. Contiguous PET scans were obtained from the midcranium to the lower chest 45 minutes after administration of 370 MBq (10 mCi) of fluorine-18 fluorodeoxyglucose (FDG). Standard uptake values (SUVs) were determined for all suspect lesions and for normal parotid glands and cerebellum.

RESULTS

All lesions were visualized, and all but two showed some increase in FDG uptake. PET findings helped correctly differentiate benign from malignant masses in 18 (69%) but were false-positive for malignancy in eight (31%). SUV analysis, lesion-to-normal SUV ratios, and lesion-to-cerebellar SUV ratios also failed to differentiate the lesions.

CONCLUSION

FDG PET is not useful in classifying salivary gland tumors as benign or malignant.

Distinguishing tumor recurrence from irradiation sequelae with positron emission tomography in patients treated for larynx cancer

PURPOSE

Distinguishing persistent or recurrent tumor from postradiation edema, or soft tissue/cartilage necrosis in patients treated for carcinoma of the larynx can be difficult. Because recurrent tumor is often submucosal, multiple deep biopsies may be necessary before a diagnosis can be established. Positron emission tomography with 18F-2fluoro-2deoxyglucose (FDG) was studied for its ability to aid in this problem.

METHODS AND MATERIALS

Positron emission tomography (18FDG) scans were performed on 11 patients who were suspected of having persistent or recurrent tumor after radiation treatment for carcinoma of the larynx. Patients underwent thorough history and physical examinations, scans with computerized tomography, and pathologic evaluation when indicated. Standard uptake values were used to quantitate the FDG uptake in the larynx.

RESULTS

The time between completion of radiation treatment and positron emission tomography examination ranged from 2 to 26 months with a median of 6 months. Ten patients underwent computed tomography (CT) of the larynx, which revealed edema of the larynx (six patients), glottic mass (four patients), and cervical nodes (one patient). Positron emission tomography scans revealed increased FDG uptake in the larynx in five patients and laryngectomy confirmed the presence of carcinoma in these patients. Five patients had positron emission tomography results consistent with normal tissue changes in the larynx, and one patient had increased FDG uptake in neck nodes. This patient underwent laryngectomy, and no cancer was found in the primary site, but nodes were pathologically positive. One patient had slightly elevated FDG uptake and negative biopsy results. The remaining patients have been followed for 11 to 14 months since their positron emission studies and their examinations have remained stable. In patients without tumor, average standard uptake values of the larynx ranged from 2.4 to 4.7, and in patients with tumor, the range was 4.9 to 10.7.

CONCLUSION

Positron emission tomography with labeled FDG appears to be useful in distinguishing benign from malignant changes in the larynx after radiation treatment. This noninvasive technique may be preferable to biopsy, which could traumatize radiation-damaged tissues and precipitate necrosis.

Conventional radionuclide cardiac imaging

For more than two decades, conventional radionuclide techniques have been employed for the noninvasive evaluation of cardiac function. Standardized techniques have been developed and are widely available. Extensive clinical experience has confirmed the reliability of these techniques and has established important roles in providing diagnostic and prognostic information. Conventional radionuclide cardiac imaging currently emphasizes the demonstration of abnormalities in myocardial perfusion and ventricular function. Myocardial and radionuclide studies are infrequently employed but can offer helpful information in specific clinical situations.

Ultrasonographic diagnosis of varicoceles

OBJECTIVE

To assess the ability of color duplex scrotal ultrasonography to detect subclinical varicoceles and confirm the diagnosis of clinical varicoceles.

DESIGN

Physical examination, color duplex scrotal ultrasonography and internal spermatic venography was performed on 64 testicular units in 33 men.

SETTING

Male fertility center.

PATIENTS

Two hundred sixty-two consecutive men being evaluated for male factor infertility of whom 33 agreed to undergo venography.

MAIN OUTCOME MEASURES

Ultrasonographic measurement of scrotal vein diameter of patients in the supine and upright position, before and during valsalva maneuver, and scrotal vein blood flow reversal with valsalva maneuver was compared with the findings of varicocele by physical examination and venography.

RESULTS

The best predictor of a varicocele was internal spermatic vein diameter, and the best overall performance of ultrasonography was achieved with the patient at rest in the supine position. The best cutoff point for venous diameter for a clinical varicocele was 3.6 mm and 2.7 mm for a subclinical varicocele, but the overall accuracy was only 63%.

CONCLUSIONS

Confirmatory studies are needed to support the ultrasonographic diagnosis of varicoceles before considering surgical repair.

Use of brain biopsy for diagnostic evaluation of patients with suspected herpes simplex encephalitis: a statistical model and its clinical implications. NIAID Collaborative Antiviral Study Group

Using the decision analysis technique and multivariate regression methods, a statistical model was established to define the utility of brain biopsy for diagnostic evaluation of patients with suspected herpes simplex encephalitis (HSE). Two strategies were compared: strategy I, brain biopsy with acyclovir (ACV) treatment for 10 days in biopsy-positive patients, and strategy II, ACV therapy without brain biopsy. Strategy I resulted in a greater 6-month survival rate when the likelihood of patients having HSE was less than 70%. Based on the current estimated prevalence of HSE (for patients with suspected HSE) of 35%, strategy I showed a slight advantage of a 3.2% increase in 6-month survival rate. An individual patient's chance of a positive brain biopsy can be predicted using a mathematical equation based on several important clinical assessments. This equation in conjunction with the decision analysis is a useful guide for the clinical management of patients with regard to brain biopsy.

Oral cholecystography vs gallbladder sonography: a prospective, blinded reappraisal

In a prospective, blinded study of 205 patients, oral cholecystography (OCG) and sonography were compared in terms of how well each screened patients for gallbladder diseases. Among 23 patients who had pathologic confirmation of the diagnosis at cholecystectomy, OCG correctly diagnosed 20 cases (87%) while sonography diagnosed 18 (78%). Among 54 patients with an abnormal OCG and/or sonogram, OCG detected 47 (87%) while sonography detected 44 (81%). These small differences in detection rates were not statistically significant. On the basis of these results, we cannot conclude that either sonography or OCG has a diagnostic advantage in screening patients for gallbladder disease. The large numbers of false-negative examinations found on both sonography and OCG suggest that in a patient with persistent symptoms, the alternative study should be performed if the first examination is negative.

The utility of adrenal scintigraphy in Cushing's syndrome and hyperaldosteronism

Thirty-three adrenal scintigrams in 30 patients were reviewed to determine the utility of this noninvasive imaging technique. It was found to be very accurate in distinguishing bilateral from unilateral hyperfunction in patients who have clinical and biochemical evidence of adrenal cortical hyperfunction. The technique proved correct in 12 of 12 cases of Cushing's syndrome and 14 of 19 cases of hyperaldosteronism. Specific clinical questions were also answered in three miscellaneous cases.

Bone marrow evaluation in small cell lung cancer

The records of 87 patients with small cell lung cancer were reviewed. Patients were clinically staged with bone marrow aspirate and biopsy as well as radionuclide scans of bone, liver, and brain. Extrathoracic spread was noted in 54% (47/87) and limited disease in 46% (40/87). The bone marrow evaluation was positive in 13/62 patients (21%) and seven of these thirteen patients had normal bone scans (54%). Of these seven patients, five had no other evidence of distant metastases and their survival was 7-10 months, considerably shorter than patients found to have limited disease. Bone marrow examination appears to complement radionuclide scanning in the initial staging of patients with small cell carcinoma of the lung and provides important prognostic information.

Relative lesion detection ability of Tc-99m HMDP and Tc-99m MDP: concise communication

To compare the efficacy of Tc-99m HMDP and Tc-99m MDP to define skeletal lesions, 28 adult patients were examined in a double-blind, randomized, crossover study. Each patient was imaged with both agents over a period of 7-14 days. Both quantitative and qualitative evaluations were performed on the resulting images. Both agents detected the same number of skeletal lesions, and the number of lesions detected was the same whether the imaging was performed 2 or 4 hr after injection. Relative uptake of the tracer in the lesion relative to normal bone was also the same for both agents. Lesions were easier to see at 4 hr after injection than at 2 hr, presumably because soft-tissue levels were lower. Retention of tracer in bone compared with soft tissue was greater, and image quality was judged to be better, with Tc-99m HMDP than with Tc-99m MDP.

Focal nodular hyperplasia of the liver imaging by differing modalities

The logistic approach in diagnosis of focal nodular hyperplasia (FNH) of the liver is discussed, based on the experience with three children. In only one child could the diagnosis be made without angiography. In that child the combination of hypervascularity on the radionuclide angiogram and uptake of the radiocolloid by Kupffer cells was sufficient for the diagnosis of FNH. If the radionuclide scintigraphy is inconclusive, angiography has to be done to show the typical features of FNH, seen in all three patients. Only if scintigraphy and angiography are not able to differentiate FNH from hepatic adenoma, biopsy or exploratory laparotomy is indicated as a final diagnostic procedure. Ultrasonography or computerized tomography is of value only in screening for hepatic mass lesions.

Alteration of gallium-67 distribution in tumor-bearing mice following treatment with methotrexate: concise communication

The effect of methotrexate (MTX) treatment upon Ga-67 distribution was investigated. Tumor bearing mice were injected with Ga-67 citrate at varying time intervals following MTX treatment administered either as a single dose or in multiple doses. Altered Ga-67 distribution was observed following MTX therapy, the general pattern showing decreased levels in blood and increased uptake in bone. MTX therapy decreased Ga-67 uptake in liver, tumor, and muscle. The effects of MTX are related to the dose and time interval between the administrations of MTX and Ga-67. The serum of MTX-treated mice had lower unsaturated iron-binding capacities and higher levels of unbound Ga-67. Serum iron and iron binding in rats determined 20 hr after MTX therapy showed significantly higher levels of serum iron and lower levels of Ga-67 in blood, and the percent transferrin saturation was approximately 95%. These observations suggest that MTX inhibition of erythropoiesis elevates serum iron levels and decreases the availability of gallium-binding sites in serum, resulting in altered Ga-67 tissue distribution.

Special characteristics and potential of single photon emission computed tomography in the brain

Single photon emission tomographic techniques for evaluation of the brain have as their major advantage the ability to employ readily available radionuclides, such as technetium-99m. With present radiopharmaceuticals, single photon emmision tomography of the brain primarily provides morphological information that may be complimentary to standard gamma camera images. Particular areas of assistance have included detection of basal lesions, delineation of multiplicity of lesions, definition of medial extent of abnormalities, clear separation of skull and intracranial abnormalities, and perhaps improved lesion characterization. Overall, however, the reported improvement in sensitivity has been relatively small. To optimally utilize the tomographic and quantiative capabilities of single emission tomography, new classes of radiopharmaceuticals must be developed that can penetrate the blood-brain barrier and provide information on CNS function and pathophysiology. If such radiopharmaceuticals can be labeled with single emission radionuclides, this technique has the potential to provide critically important information. The ultimate outcome of single emission tomographic techniques for the study of the brain may depend on radiopharmaceutical advances.

A comparison of brain imaging with gamma camera, single-photon emission computed tomography, and transmission computed tomography: concise communication

We have evaluated the utility of a single-photon axial tomographic scanner (ECT) in brain imaging, using routine tracers in 238 patients. When compared with routine delayed gamma-camera images (DGCI), there was agreement in 191 negative studies and 39 positive studies. Four patients had positive DGCI and negative ECT studies, and four had positive ECT and negative DGCI. In the 102 patients in this series who also had transmission CT (TCT) studies, there were five who had positive emission studies and negative TCT, and 38 with an abnormal TCT and normal ECT. The ECT was occasionally helpful in distinguishing brain and skull metastases, in better portrayal of deep lesions, and in resolving equivocal DGCI findings. For the ECT to become clinically rewarding, however, we feel that it will need development of new tracers that will provide functional information in addition to that already attainable by routine gamma-camera images.

Comparison of Tc-99m pyrosphosphate and Tc-99m hydroxymethylene diphosphonate in acute myocardial infarction: concise communication

A clinical comparison between a new bone seeking radiopharmaceutical, Tc-99m hydroxymethylene diphosphonate (TcHMDP) and the standard agent, Tc-99m pyrophosphate (TcPPi), was performed in 18 patients with acute myocardial infarction. Each patient was imaged initially with either TcHMDP or TcPPi, and imaged 24 hr later with the other tracer. All 18 patients had images positive for acute myocardial infarction with TcPPi, whereas 16 of 18 patients (89%) had positive studies with TcHMDP. The TcPPi images were graded significantly superior to those obtained with TcHMDP in 61% of the patients, and they were equal in 33%. In only one patient (6%) was TcHMDP better. The results indicate that compared with TcHMDP, TcPPi not only has a superior sensitivity for acute myocardial infarction but also has a significantly increased intensity of uptake in positive areas. TcPPi remains the agent of choice for myocardial infarct imaging.

Comparison of Tc-99m pyrophosphate and Tc-99m methylene diphosphonate in acute myocardial infarction: concise communication

This study compared Tc-99m pyrophosphate (PPi) and Tc-99m methylene diphosphonate (MDP) for myocardial infarct imaging in 24 patients with diagnosed acute myocardial infarction. The radiopharmaceuticals were administered randomly and interpreted without knowledge of the sequence used. Twenty-three patients (96%) had positive Tc-99m PPi scintigrams, but only 17 (71%) had a positive Tc-99m MDP study (P less than 0.05). In addition, a comparison of the relative intensity with each agent revealed greater intensity with Tc-99m in 21 cases, equal intensity in two cases, and less intensity in only one case (p less than 0.001). These findings support the superiority of Tc-99m PPi as the agent of choice for myocardial scintigraphy in acute infarction.