Indeterminate Scans Research Articles

Preliminary results of a bone marrow magnetic resonance imaging protocol for patients with high-risk prostate cancer

Objectives. To compare the accuracy of a bone marrow magnetic resonance imaging (MRI) protocol in patients at high risk of metastatic disease with radioisotopic bone scans, the standard method for detection of bony metastases in patients with prostate cancer. Methods. The study group consisted of 19 men with prostate cancer who underwent a bone marrow MRI between November 1993 and February 1996. This protocol images the marrow of the thoracolumbar spine, sacrum, pelvis, and femurs. Indications for MRI included an equivocal bone scan and/or staging of locally advanced or recurrent disease. The findings on MRI and bone scan were compared and the results correlated with the subsequent clinical patient outcome. Results. The bone marrow MRI protocol detected metastatic disease in 1 (7%) of 13 patients with negative bone scans. Four patients had an indeterminate bone scan: 2 had true-positive MRIs, 1 a true-negative MRI, and 1 a false-positive MRI on the basis of subsequent clinical follow-up. Two patients with positive bone scans had true-positive MRIs. Conclusions. Although not recommended for routine staging, MRI was useful in this study for clarifying an equivocal bone scan. The bone marrow MRI protocol images a high yield volume of the bony skeleton and is fast and economical compared with obtaining many focused MRI scans of these areas separately. These preliminary data suggest that further investigation of its clinical utility for staging locally advanced or recurrent disease is justified.

Efficacy of Three-Phase Bone Scans in Evaluating Diabetic Foot Ulcers

To evaluate the utility of bone scans in determining the treatment of diabetic patients with foot ulcers, a retrospective study was conducted. Medical records were reviewed for clinical signs of infection, laboratory data, and the radiologists' interpretations of imaging studies. During the study period, 34 bone scans were obtained by the treating physicians to evaluate diabetic foot ulcers. Among these, 22 of 34 bone scans were markedly confirmatory of being "consistent with osteomyelitis," 8 of 34 were moderately confirmatory ("indeterminate with regard to osteomyelitis"), and 4 of 34 were not confirmatory ("not consistent with osteomyelitis"). Of the 22 patients in the markedly confirmatory group, eight patients with clinical findings of uncontrolled infection or gangrene were treated with partial or complete amputation, whereas all others (14 patients) were treated with local wound care+/-intravenous antibiotics. Among the eight bone scans interpreted as indeterminate, three patients required partial or complete amputation, whereas the other five patients were managed with local wound care. Of the four patients with nonconfirmatory bone scans, two patients had evidence of dry gangrene and required amputation, whereas the other two patients did not have clinical evidence of infection or gangrene and were treated with local wound care. There was no significant difference in the amputation rate for patients with confirmatory, indeterminate, or nonconfirmatory bone scans for osteomyelitis (36%, 37%, and 50%, respectively) (P > 0.5). Therefore, the authors concluded that the ultimate treatment should be based on clinical indicators of the presence of uncontrolled infection or gangrene rather than on bone scan findings.

Acute pulmonary embolism: ancillary findings at spiral CT.

To determine the value of parenchymal findings at contrast material-enhanced spiral computed tomography (CT) in patients suspected to have pulmonary embolism (PE). Eighty-eight patients suspected to have PE underwent contrast-enhanced spiral CT and ventilation-perfusion scintigraphy. Concordance between CT and scintigraphic results was used to diagnose or exclude PE. Pulmonary angiography was attempted in all patients with discordant CT and scintigraphic results or indeterminate scans. Parenchymal CT scans were assessed by two radiologists who were not aware of the diagnosis and who had access only to lung window images. Twenty-six patients had PE; 62 did not. Wedge-shaped pleural-based consolidation was seen in 16 patients with PE (62%) and 17 patients without PE (27%) (P < .05) (sensitivity, 62%; specificity, 73%). Linear bands were seen in 12 patients with PE (46%) and 13 patients without PE (21%) (P < .05) (sensitivity, 46%; specificity, 79%). There was no statistically significant difference in the frequency of non-wedge-shaped consolidation, areas of decreased attenuation, or atelectasis. Central and lower-lobe segmental pulmonary arteries that contained emboli were enlarged (P < .05). Parenchymal findings may suggest further investigations when results of spiral CT are inconclusive in diagnosis of PE.

Prospective study of blunt aortic injury: helical CT is diagnostic and antihypertensive therapy reduces rupture.

There were two aims of this study. The first was to evaluate the application of helical computed tomography of the thorax (HCTT) for the diagnosis of blunt aortic injury (BAI). The second was to evaluate the efficacy of beta-blockers with or without nitroprusside in preventing aortic rupture. Aortography has been the standard for diagnosing BAI for the past 4 decades. Conventional chest CT has not proven to be of significant value. Helical CT scanning is faster and has higher resolution than conventional CT. Retrospective studies have suggested the efficacy of antihypertensives in preventing aortic rupture. A prospective study comparing HCTT to aortography in the diagnosis of BAI was performed. A protocol of beta-blockers with or without nitroprusside was also examined for efficacy in preventing rupture before aortic repair and in allowing delayed repair in patients with significant associated injuries. Over a period of 4 years, 494 patients were studied. BAI was diagnosed in 71 patients. Sensitivity was 100% for HCTT versus 92% for aortography. Specificity was 83% for HCTT versus 99% for aortography. Accuracy was 86% for HCTT versus 97% for aortography. Positive predictive value was 50% for HCTT versus 97% for aortography. Negative predictive value was 100% for HCTT versus 97% for aortography. No patient had spontaneous rupture in this study. HCTT is sensitive for diagnosing intimal injuries and pseudoaneurysms. Patients without direct HCTT evidence of BAI require no further evaluation. Aortography can be reserved for indeterminate HCTT scans. Early diagnosis with HCTT and presumptive treatment with the antihypertensive regimen eliminated in-hospital aortic rupture.

Clinicians' interpretation of the indeterminate ventilation-perfusion scan report.

Most patients with suspected pulmonary embolism are initially investigated by radio-nuclide ventilation-perfusion (VQ) scanning. Approximately 70% of VQ scans are "indeterminate". Further investigations should be considered in such patients in order to establish a definitive diagnosis. However, these investigations are rarely requested in patients with indeterminate scans in our institution. We therefore decided to review the casenotes of such patients to determine their subsequent management. Over a 9 month period, 131 (32%) out of a total of 413 consecutive VQ scans were reported as indeterminate. The casenotes of 111 of these patients (65 female, 46 male, mean age 65 years, range 17-91 years) were reviewed. 52 of the 111 patients (46%) were treated on clinical grounds without further investigation; 12 patients (11%) had further investigation; and in 39 of the cases (35%) the VQ scan report was misinterpreted. 20 (38%) of the 52 patients managed on clinical grounds were treated for pulmonary embolus with anticoagulation and 26 (50%) were not anticoagulated. Of the 12 patients who were investigated further, nine had lower limb Doppler ultrasound and three had contrast venography. No patients had pulmonary angiography. Of the 39 cases where the VQ report was misinterpreted, the result was misquoted in the casenotes of 37 (95%) as negative for PE and none of these patients were anticoagulated, and in two cases (5%) it was misquoted as positive for PE and anticoagulant therapy was instituted. The misunderstanding was observed in all clinical firms. Such misinterpretation may have significant implications, since 30-40% of patients with indeterminate scans may have had PE. Our findings suggest that clinicians need to be better informed of the significance of an indeterminate VQ scan result.

Pelvic Ultrasound Performed by Emergency Physicians for the Detection of Ectopic Pregnancy in Complicated First-Trimester Pregnancies

Study objective: To determine the accuracy and application of pelvic ultrasound performed by emergency physicians in detecting ectopic pregnancy (EP) in complicated first-trimester pregnancies. Methods: We studied consecutive pelvic ultrasounds performed in all women who presented with abdominal pain or vaginal bleeding during the first trimester of pregnancy over a 6-month period. Patients with clinical evidence of incomplete abortion were not included. We compared ultrasound results with subsequent ultrasound findings by the radiology department and correlated them with follow-up diagnoses and outcomes. Results: Of the 136 eligible patients, a final diagnosis was rendered in 125; 11 were lost to follow-up. These ED ultrasound findings were recorded: established intrauterine pregnancy (IUP) with embryonic structures, 87 (70%); indeterminate scan revealing no distinct evidence of IUP or EP, 15 (12%); early intrauterine gestational sac of less than 6 weeks without embryonic structures, 12 (10%); EP, 8 (6%); blighted ovum, 2 (2%); and molar pregnancy, 1 (1%). The initial ED ultrasound determination was consistent with radiology department findings, final outcome, or both in 121 (96%) (95% confidence interval [CI], 91% to 97%). ED ultrasound accurately identified 87 pregnancies with intrauterine embryonic structures, including 5 patients with fetal demise (95% CI, 97% to 100%). Diagnosis of pregnancy location in these 87 patients effectively ruled out EP, with a negative predictive value of 100%. The sensitivity and specificity of ED ultrasound in the detection of EP were 90% and 88%, respectively. Conclusion: Pelvic ultrasonography performed by emergency physicians can be used to rule out EP and make an accurate diagnosis in most patients with complicated first-trimester pregnancies during the initial ED visit. The remaining patients at risk can be identified and a diagnosis made by means of follow-up ultrasound and serial hCG determinations. [Durham B, Lane B, Burbridge L, Balasubramaniam S: Pelvic ultrasound performed by emergency physicians for the detection of ectopic pregnancy in complicated first-trimester pregnancies. Ann Emerg Med March 1997;29:338-347.]

Ventilation-perfusion lung scanning and spiral computed tomography of the lungs: competing or complementary modalities?

The recently developed technique of spiral computed tomographic angiography (CTA) is being used for the detection of pulmonary emboli (PE), and several studies have assessed its accuracy using pulmonary angiography as the gold standard. CTA shows a high level of accuracy in the detection of pulmonary emboli in segmental or larger central vessels. The specificity is high enough to eliminate the requirement for angiography if a positive CTA result is found. The main factor limiting the sensitivity of CTA is the frequency of peripheral emboli in the vessels outside the central chest field covered by CTA. The incidence of such peripheral emboli varies in different reports from 0% to 36%, and their significance remains arguable. Interpretative criteria for V./Q.- lung scintigraphy have been refined as a result of the lessons learned from the PIOPED study. Using these modified criteria, and taking into account the prior probability of PE based on the presence or absence of clinical risk factors, treatment decisions can be reasonably made in patients in the following categories: those with normal lung scans, those with high probability scans and high prior probability of PE, and those with low probability scans and low clinical suspicion. Patients with intermediate probability or indeterminate scans, and those in whom the scan results conflict with the clinical expectation, will need further tests. Ultrasound examination of the leg veins, if positive, will select a further subgroup of patients for active treatment. Patients with a negative or inconclusive ultrasound result, who previously have been candidates for pulmonary angiography, can now go on to CTA. The advantages in specificity which CTA offers will make it an important part of the diagnostic workup for selected patients, but in view of its increased cost and high radiation dose compared with V./Q. scintigraphy, the argument that CTA should completely replace lung scintigraphy is currently unsupportable.

Compression sonography in patients with indeterminate or low-probability lung scans: lack of usefulness in the absence of both symptoms of deep-vein thrombosis and thromboembolic risk factors.

We sought to determine whether compression sonography could be eliminated in the evaluation of patients who lacked both thromboembolic risk factors and symptoms of deep-vein thrombosis and who had an indeterminate or low-probability lung scan. The medical records of 155 consecutive patients who underwent bilateral lower-extremity sonography after an indeterminate or low-probability lung scan were reviewed. The presence of thromboembolic risk factors and deep-vein thrombosis symptoms and the result of sonography were recorded. Patients were divided into two groups: group 1 consisted of patients with either thromboembolic risk factors or deep-vein thrombosis symptoms, and group 2 consisted of patients without thromboembolic risk factors and without deep-vein thrombosis symptoms. The incidences of deep-vein thrombosis in groups 1 and 2 were compared by use of a two-tailed Fisher's exact test. Thromboembolic risk factors or deep-vein thrombosis symptoms were found in 109 of 155 patients (70%) (group 1). Deep-vein thrombosis was found in nine of 108 patients (8%) in group 1. Both thromboembolic risk factors and deep-vein thrombosis symptoms were absent in 47 of 155 patients (30%) (group 2). Deep-vein thrombosis was found in none of 47 patients (95% confidence interval, 0-8%) in group 2. The difference in the incidences of deep-vein thrombosis in groups 1 and 2 approached statistical significance (p = .0579). The negative predictive value of the absence of both thromboembolic risk factors and deep-vein thrombosis symptoms in excluding deep-vein thrombosis was 100% (95% confidence interval, 93-100%). If both symptoms of deep-vein thrombosis and thromboembolic risk factors are absent, the usefulness of lower-extremity sonography in detecting deep-vein thrombosis in patients with an indeterminate or low-probability lung scan is low. The manner in which these findings may be used to modify individual practice patterns will undoubtedly depend on the rate of detection of deep-vein thrombosis at a given institution.

Lesion Localization in Periodic Lateralized Epileptiform Discharges: Gray or White Matter

We analyzed the results of neuroimaging studies in patients with periodic lateralized epileptiform discharges (PLEDs) or bilateral independent periodic lateralized epileptiform discharges (BIPLEDs) for localization of lesions in gray or white matter to determine if "cortical isolation" is a critical mechanism in the pathogenesis of this phenomena. We assessed 32 patients who had undergone computed tomography (CT) exclusively and 8 patients who had undergone magnetic resonance imaging (MRI) with or without CT. The superior resolution necessary for adequate lesion localization allowed use of only the MRI scans from the 8 patients. Six patients had scans with cortical and subcortical gray and white matter lesions, and 1 patient had a cortical gray matter lesion only. One patient had an indeterminate scan. No patient had white matter lesions only. Our findings in patients with PLEDs and BIPLEDs correlate with postmortem data in patients with generalized periodic EEG patterns that show consistent localization of lesions in the gray matter. These findings do not support cortical isolation as the critical or sole mechanism in PLEDs or BIPLEDs.

Platelet Count, Antiplatelet Therapy and Pulmonary Embolism-A Prospective Study in Patients with Hip Surgery

Pulmonary embolism (PE) is a serious complication following hip surgery. Trials of antiplatelet thromboprophylaxis indicated a substantial reduction in PE rate, and we prospectively studied the effect of a combination of low-dose heparin and two different antiplatelets. Furthermore, our experience in previous studies suggested that platelet count (PC) levels could be useful to reliably suspect PE at a very early stage, and we prospectively tried to confirm our previous findings. Ours is a prospective study in 459 consecutive patients operated on because of hip fracture (265) or elective hip replacement (194), aimed to determine: 1) whether the benefits of antiplatelets plus heparin on PE outweigh the risks; 2) to assess the clinical usefulness of PC monitoring in these patients, so as to confirm whether PE could be recognized early. It was a prospective, randomized, double-blind study. All patients received unfractioned heparin (7500 IU sc twice daily, starting 2 h before operation). In addition, they received aspirin (200 mg thrice daily, with meals), Triflusal (300 mg thrice daily, with meals), or placebo. Real time B-mode ultrasonography (US) was performed on all patients on the 8-9th day after surgery. Venography was performed in patients with normal US, if clinical symptoms suggested venous thrombosis. Twelve out of the 459 patients (2.6%) had to discontinue prophylaxis, because of major bleeding (6 patients), or gastric intolerance (6 patients). There were no significant differences between groups in either deep vein thrombosis (26 patients (18%) with aspirin, 18 (12%) with Triflusal, 26 (17%) with placebo), or PE development (7 patients (5%) with aspirin, 3 (2%) with Triflusal, 8 (5%) taking placebo).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognosis in a Patient With an Initial Normal Pulmonary Angiogram

A 58-year-old man with pleuritic chest pain and an indeterminate lung scan had normal results of Duplex ultrasound studies of the lower limbs and a normal pulmonary angiogram. Recurrent symptoms led to repeated pulmonary angiography and a diagnosis of pulmonary embolism. This case emphasizes the possibility of missing an initial, or developing a subsequent, pulmonary embolism despite a normal angiogram and reinforces the need for serial studies if a noninvasive strategy for the diagnosis of pulmonary embolism is to be employed.

Pulmonary Embolism in Patients with Upper Extremity DVT Associated to Venous Central Lines - A Prospective Study

We performed a prospective study in 86 consecutive patients with central vein catheter-related deep venous thrombosis (DVT) of the upper extremity, to evaluate the prevalence of pulmonary embolism (PE), and to identify clinical variables that would increase the likelihood of developing PE in an individual patient. Since upper-extremity DVT was established, all patients received intravenous heparin therapy. Then, a ventilation-perfusion lung scan was obtained within 24 h of DVT diagnosis, whether respiratory symptoms were present or not. Six points of clinical information were recorded on entering in the study, and then compared with the scintigraphic findings: age, sex, the underlying disease, the catheter material, the character of the infusate, and the duration of cannulation. Thirteen patients were considered to have PE. Sixty-six patients were finally classified as having a normal lung scan, and 7 patients were excluded from the study (because of indeterminate lung scan 6; because of femoropopliteal thrombosis simultaneously present 1). Two out of the 13 patients with PE subsequently died because of recurrent, massive embolism, despite adequate heparin therapy. PE was more commonly present in patients with polyvinyle chloride or polyethylene catheters (10/38, 26%) as compared to patients with either polyurethane or siliconized catheters (3/41, 7%; p < 0.05, Chi-Square test; Odds Ratio = 4.52, 95% CI 1.01-23.07). We conclude that PE is not a rare event in these patients, and it may be life-threatening even despite adequate heparin therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal gallbladder nuclear ejection fraction predicts success of cholecystectomy in patients with biliary dyskinesia

The management of patients with symptoms consistent with biliary tract disease who do not have gallstones is difficult. We retrospectively reviewed the charts of 18 patients who underwent cholecystokinin cholescintigraphy at our institution to determine if this procedure was reliable in identifying patients who would benefit from cholecystectomy. All patients underwent biliary screening, and a gallbladder ejection fraction of less than or equal to 35% was considered abnormal. None of the patients had evidence of gallstones by ultrasound. There were 11 patients with abnormal ejection fractions. All 11 patients (100%) had "classic" biliary colic and underwent cholecystectomy. The pathologic diagnosis was chronic cholecystitis in every patient. All patients had complete relief of their symptoms postoperatively with a mean follow-up of 10 months. There were six patients with normal ejection fractions. Only one patient in this group had "classic" biliary colic. This patient had a gallbladder ejection fraction of 38% and endoscopic evidence of gastritis. This patient remains symptomatic despite H2 blockade. The remaining five patients had nonspecific right upper quadrant or epigastric pain. These patients had endoscopic evidence of gastritis, and symptoms were relieved with H2 blockade. The remaining patient had an indeterminate scan due to radioactivity in the duodenum overlying the gallbladder and was excluded from this analysis. Cholecystokinin cholescintigraphy is a useful test in identifying those patients with biliary dyskinesia or acalculous cholecystitis who will benefit from cholecystectomy.

MCA Serum Determination in Breast Carcinoma Patients for the Diagnosis of Bone Metastases

Serum MCA levels were determined in 173 consecutive patients with breast cancer in order to assess the clinical utility of MCA for the detection of bone metastases. Bone pathology was diagnosed by scintigraphy, radiology and clinical follow-up. Metastases were found in 37 patients, benign lesions in 25, and in 111 no bone lesions were found. Eighteen of the 173 bone scans were considered indeterminate for metastases. Based on the receiver-operating characteristic curves (ROC) analysis, the cut-off level for MCA was set at 20 U/ml. Only in 4 of the 37 patients with bone metastases MCA was below 20 U/ml. All 4 patients had completed their chemotherapy course within six months before MCA determination. Only in 6 patients of the 136 without bone metastases MCA levels were above 20 U/ml. Of the 18 patients with indeterminate bone scans, 15 had benign lesions and all of them had MCA levels below 20 U/ml. MCA determination is a sensitive method for the detection of bone metastases in breast carcinoma. We encourage the use of this procedure for the selection of high-risk groups or as a complementary method for the interpretation of bone scintigraphy.

Color Doppler Ultrasound and Deep Venous Thrombosis

Letters1 June 1993Color Doppler Ultrasound and Deep Venous ThrombosisRichard H. White, MDRichard H. White, MDSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-118-11-199306010-00019 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:Davidson and colleagues [1] report that color Doppler ultrasound has poor diagnostic accuracy for proximal thrombi in high-risk asymptomatic patients receiving medical prophylaxis. The results of this study could affect clinical practice in several different situations. Although clinicians rarely order an ultrasound screening test in patients receiving heparin prophylaxis, they do screen patients at high risk for thrombosis who cannot be given prophylaxis [2] and patients with suspected pulmonary embolism who have an indeterminate lung scan. The low accuracy of ultrasound suggests that venography should be ordered in these situations. However, some reservations about the study methods ...

The Use of Prostate-Specific Antigen in Staging Patients With Newly Diagnosed Prostate Cancer

To assess the need for obtaining radionuclide bone scans in the staging evaluation of patients with newly diagnosed, untreated prostate cancer. This determination was made on the basis of presenting prostate-specific antigen (PSA) levels. Retrospective review. The medical records of 2064 consecutive patients with prostate cancer who were evaluated at the Mayo Clinic in Rochester, Minn, from January 1989 through December 1990 were reviewed. Eight hundred fifty-two patients with newly diagnosed, untreated disease and a serum PSA concentration less than 20.0 micrograms/L at presentation comprised the study population. The rate of false-negative results associated with using the serum PSA concentration to predict bone scan findings. Five hundred sixty-one patients had a serum PSA concentration of 10.0 micrograms/L or less; only three had an abnormal bone scan result, and one had an indeterminate scan result. Of the 467 men whose PSA value was 8.0 micrograms/L or less (two times the upper limit of the reference range), none had bone scan results that were either abnormal or indeterminate. The rate of false-negative results for an abnormal bone scan result was 0% with a serum PSA value of 8.0 micrograms/L or less and 0.5% with a cutoff level of 10.0 micrograms/L. The 95% upper confidence limit for the rate of false-negative results for all PSA cutoff levels less than 20.0 micrograms/L was less than 2%. For patients with newly diagnosed, untreated prostate cancer, a serum PSA concentration of 10.0 micrograms/L or less, and no skeletal symptoms, a staging radionuclide bone scan does not appear to be necessary. This clinical situation applies to 39% of all patients presenting with newly diagnosed prostate cancer. Since more than 130,000 new cases are diagnosed each year, approximately 50,000 patients are affected annually. If the $600 staging bone scan were eliminated for these patients, a significant economic savings to the health care system in this country would be effected.

Diagnostic strategies in acute pulmonary embolism.

A firm diagnosis of pulmonary embolism (PE) to prevent over- or undertreatment requires an integrated use of ventilation-perfusion lung scintigraphy (V/Q scan), a recent chest X-ray, bilateral selective pulmonary angiography and venous studies. The V/Q scan should be reported in terms of probabilities according to defined criteria and be combined with clinical probabilities before a treatment decision is made. A negative V/Q scan, a low-probability scan combined with low clinical suspicion or a high-probability scan with a high clinical suspicion is generally conclusive. Patients with intermediate (indeterminate) scan probability or with discordant scintigraphic clinical probability need further work-up with pulmonary angiogram or venous studies. If neither scintigraphy nor pulmonary angiography is available, accurate venous studies of the lower legs may guide treatment decision in patients suspected of having PE. We need more research to define if all patients with PE but only a minor or no clot burden proven by venous studies really need treatment.

Upper-Extremity Deep Venous Thrombosis and Pulmonary Embolism: A Prospective Study

We prospectively evaluated the prevalence of pulmonary embolism (PE) in 30 consecutive patients with proved deep venous thrombosis (DVT) of the upper extremity. Ten patients (seven male and three female; mean age, 43 years) had primary DVT, and 20 patients (14 male and six female; mean age, 52 years) had catheter-related DVT. Ventilation-perfusion lung scans were routinely performed at the time of hospital admission to all but one patient (one patient was critically ill, and he died four days after DVT diagnosis because of massive PE). Lung scan findings were normal in nine of ten patients with primary DVT, and they were indetermine in the remaining patient. By contrast, perfusion defects were considered highly suggestive of PE in four patients with catheter-related DVT; two patients had indeterminate lung scans, and 13 patients had normal scans. We conclude that PE is not a rare complication in upper extremity DVT, and that patients with catheter-related DVT seem to be at a higher risk.

Factors contributing to the occurrence of an indeterminate lung scan

Factors contributing to the occurrence of an indeterminate lung scan

Plasma cross linked fibrin degradation products in pulmonary embolism.

Plasma concentrations of cross linked fibrin degradation products, a marker of intravascular thrombosis and fibrinolysis, were measured in 495 patients with suspected pulmonary embolism referred for ventilation-perfusion lung scanning to determine whether concentrations are increased in pulmonary embolism and their potential use in diagnosis. Lung scans were described as normal (n = 66) or as showing a low (n = 292), indeterminate (n = 58), or high probability (n = 79) of pulmonary embolism. There was a difference between the mean levels of cross linked fibrin degradation products in each scan category: normal scans, 142 ng/ml; low probability scans, 295 ng/ml; indeterminate probability scans, 510 ng/ml; high probability scans, 952 ng/ml (p less than 0.001). Of the patients with high probability scans, 96% had raised concentrations. Explanations for discrepant low results include incorrect scan diagnosis, delay in blood sampling, and anticoagulation. Of the patients with a low or indeterminate probability of pulmonary embolism, 43% had increased concentrations of cross linked fibrin degradation products that could be attributed in most cases to another illness. Owing to the wide range of values in each lung scan diagnostic category, raised concentrations of these fibrin degradation products cannot be used without reference to the patient's clinical state as a discriminatory test for pulmonary embolism. Further evaluation of the significance of normal concentrations in excluding a diagnosis of pulmonary embolism appears to be warranted.