Defining radiographic criteria for flexion-extension studies of the cervical spine.

STUDY OBJECTIVE: We sought to describe and measure 3 radiographic variables in normal male volunteers and determine whether these variables could be useful in establishing more objective radiographic criteria for evaluation of flexion-extension studies of the cervical spine. In addition, we hypothesized that patients with a normal cervical spine should not have greater than 2 mm of subluxation present with flexion or extension. METHODS: A prospective, observational study of normal male volunteers between the ages of 18 and 40 years was performed. We obtained radiographs of all participants in neutral, flexion, and extension positions and measured the amount of subluxation and interspinous distance, as well as the degree of vertebral angulation between C3 and C7. RESULTS: One hundred male volunteers were included in the study. Subluxation during flexion (compared with neutral) was greater than 2 mm in none of the participants at each level from C3 to C7 (95% confidence interval [CI] 0 to 3.6); subluxation in extension was greater than 2 mm in one participant at one level from C3 to C4 (95% CI 0 to 5.5) and none of the participants at each of the remaining 3 levels from C4 to C7 (95% CI 0 to 3.6). Comparing flexion with the neutral position, the mean vertebral angulation and SD were 24.2 degrees and 13.3 degrees, and the 95% certainty interval (CEI) was -1.9 to 50.2. Comparing extension with the neutral position, the mean vertebral angulation was 14.1 degrees, with an SD of 13.3 degrees, and the 95% CEI was -4.6 to 32.8. The mean change in interspinous distance between the neutral position and flexion varied from 1.2 to 4.6 mm (SD 1.7 to 2.4 mm), depending on the level of cervical spine studied. When comparing the neutral position and extension, the mean change in interspinous distance varied from 1.2 to 2.2 mm (SD 1.7 to 1.9). CONCLUSION: Currently, there are no clinically validated criteria for evaluating flexion-extension studies of the cervical spine. Our study suggests that subluxation greater than 2 mm in men 18 to 40 years of age may be a useful variable for further study as an indicator of ligamentous injury. Interspinous distance and vertebral angulation appear less likely to have useful clinical application.

Thallium-201 brain SPECT of lymphoma in AIDS patients: pitfalls and technique optimization.

PURPOSE: Our aim was to examine the 201Tl-SPECT scans in AIDS patients with focal CNS lesions to identify those studies with a false-positive or false-negative result to determine any potential pitfalls in interpretation as well as to suggest methods for technique optimization. METHODS: We retrospectively reviewed the charts of 162 AIDS patients with cerebral mass lesions on 201Tl-SPECT studies. One hundred sixty-one patients had CT examinations, of which 50 also had MR studies. One patient had MR imaging without CT. Those patients in whom the diagnosis by 201Tl-SPECT did not correspond with the known pathologic or clinically proved diagnosis were then singled out and their CT, MR, and 201Tl-SPECT studies were reviewed, including blinded interpretation of the 201Tl-SPECT scans alone and alongside the corresponding CT and MR examinations. Studies were examined for lesion morphology, size, location, enhancement pattern, and presence of necrosis. The review of the 201Tl-SPECT studies included both a qualitative approach (subjective analysis of the scans for areas of abnormally increased uptake) and a quantitative approach (comparison of lesion activity versus activity within a reference standard, such as the scalp). RESULTS: Sensitivity and specificity of 201Tl-SPECT in depicting lymphoma were 100% and 93%, respectively, based on the initial qualitative analysis. Fifty-one patients had positive 201Tl-SPECT results, of whom 43 were determined to have lymphoma (four by biopsy/autopsy, 39 by clinical and radiologic findings). Upon reevaluation with both a quantitative and qualitative approach, those studies initially interpreted as positive in patients without lymphoma (false positives) were found to be negative. CONCLUSION: Brain 201Tl-SPECT is an effective study in the diagnosis of CNS lymphoma in AIDS patients. Specificity can be increased by routinely performing a quantitative analysis of all lesions.

Intra-aortic balloon counterpulsation augments cerebral blood flow in the patient with cerebral vasospasm: a xenon-enhanced computed tomography study.

OBJECTIVE: We previously established the ability of intra-aortic balloon counterpulsation (IABC) to improve cerebral blood flow (CBF) significantly in a canine model of cerebral vasospasm. This study was performed to assess the efficacy of IABC in a patient with cardiac dysfunction and severe cerebral vasospasm that was refractory to traditional treatment measures. METHODS: We report our experience with the clinical use of IABC to treat cerebral vasospasm in a patient who suffered subarachnoid hemorrhage and concomitant myocardial infarction. Hypertensive, hypervolemic, hemodilution therapy was ineffective, and IABC was instituted. Xenon-enhanced computed tomography (Xe-CT) was utilized to obtain serial measurements of CBF with and without IABC over a 4-day period. RESULTS: IABC dramatically improved cardiac function in this patient, and Xe-CT demonstrated significant improvement in CBF with IABC. The average global CBF was 20.5 +/- 4.4 ml/100g/min before versus 34.7 +/- 3.8 ml/100g/min after IABC (p < 0.0001, paired student's t-test). The lower the CBF before IABC, the greater the improvement with IABC (correlation coefficient r = 0.83, p = 0.0007). CBF improvement ranged from 33% to 161% above baseline, average 69.3%. No complications of IABC were observed. CONCLUSIONS: This is the first report demonstrating the ability of IABC to improve CBF in a patient with vasospasm. We suggest that IABC is a rational treatment option in select patients with refractory cerebral vasospasm who do not respond to traditional treatment measures.

Nuclear medicine applications to the neuroimaging of AIDS. A neuroradiologist's perspective.

The human immunodeficiency virus (HIV) responsible for AIDS is reaching epidemic proportions in the United States and Europe. As new therapeutic modalities against HIV are uncovered and applied to treat prophylactically asymptomatic and therapeutically symptomatic HIV positive patients, imaging studies are no longer used just to characterize the organic-morphologic effects of HIV and opportunistic infections and neoplasms. This article discusses the current applications and contribution of nuclear medicine to the management of neurologically symptomatic HIV-positive patients.

Primary central nervous system lymphoma in patients with AIDS.

Primary central nervous system lymphoma (PCNSL), once considered a rare brain neoplasm, has been steadily increasing in incidence mainly due to an enlarging population of immunosuppressed patients. PCNSL has become the second most common brain space occupying lesion in patients with the acquired immunodeficiency syndrome. A rapid diagnosis of this entity may represent weeks to months of survival to immunosuppressed HIV-positive patients. The radiologist now plays an important role in the noninvasive diagnosis and management of this condition through the accurate interpretation of imaging findings provided by CT, MR, and brain SPECT studies. This article focuses on the pathogenesis, clinical manifestations, neuropathology, and imaging characteristics of this brain neoplasm. New accurate imaging algorithms combining the diagnostic information provided by CT, MR, and T1-201 brain SPECT are discussed.

Review of tests for monitoring doxorubicin-induced cardiomyopathy.

The objective of this review is to make physicians aware of new radionuclide methods to detect cardiac effects of chemotherapeutic drugs. This knowledge is important because of the limitations of the physical examination and the electrocardiogram for detecting early reversible cardiac damage. Presently left ventricular ejection fraction (LVEF) is routinely used to screen for cardiotoxicity. Since LVEF obtained by radionuclide angiocardiography is more accurate than the LVEF estimated by echocardiography, serial radionuclide LVEF monitoring is most commonly used to monitor cardiotoxicity. Diastolic measurements of left ventricular function (such as peak filling rate) are now being added to routine LVEF measurements to enhance standard radionuclide evaluation. This screening test should be done prior to beginning therapy and at appropriate points based on the baseline study, therapy scheme and the patient's clinical status. At some centers, exercise LVEF methods are being used to determine if cardiac reserve is adequate for the patient to tolerate additional chemotherapy when cardiac injury may be present. Previously, endomyocardial biopsy was needed to detect and confirm early anthracycline cardiotoxicity. This invasive test may be replaced by a new noninvasive in vivo method using radioactive monoclonal antibodies against cardiac muscle (indium-111-antimyosin). Because cardiac failure has been associated with adrenergic neuron injury, it has been proposed that radioactive methyliodobenzylguanine may detect the adrenergic abnormality which may predict future development of congestive heart failure or sudden death months after therapy is discontinued. Advantages and disadvantages of these methods in evaluating cardiotoxicity, and an algorithm to optimally monitor antitumor therapy-induced cardiomyopathy are discussed.

Reduction of neutrophil margination by L-arginine during hypothermic cardiopulmonary bypass in a pig model.

Nitric oxide generation by L-arginine (2 mg/kg/min) infusion during cardiopulmonary bypass (CPB) increases blood flow to all organs and reduces cytokine induced organ damage by reducing the level of marginating neutrophils (Ns). The N-trapping in the oxygenator (OX), arterial filter (AF), cardiotomy reservoir (CR), and N-margination were quantified with indium 111 labeled autologous neutrophils (INN) in nine groups of 40 Yorkshire pigs (30-35 kg). Cardiopulmonary bypass (180 min or 90 min CPB, 90 min reperfusion) was carried out at 2.5-3.5 L/min and at two temperatures (18 degrees C, 28 degrees C). The INN (650-780 microCi) was administered intravenously 15 mins before CPB. All pigs received heparin systemically (activated coagulation time > 400 secs); CPB was instituted with a roller pump, OX (Univox 1.8 m2), AF (0.25 m2), and CR (BCR-3500, Bentley Lab, Irvine, CA). The INN distribution in the device (OX, AF, CR) and organs was imaged with a gamma camera and measured with an ion chamber and a gamma counter. The LA infusion decreased N-trapping, estimated as the percent of injected INN (mean +/- standard deviation), in OX from control (2.7 +/- 2.02)% to (0.94 +/- 0.29)%, and margination in lung from control (48 +/- 4)% to minimal levels (23 +/- 2)% (p < 0.01). In the CPB reperfusion group, a beneficial effect was observed at LA low dose and toxicity of higher N-margination at 15 mg/ kg/min. Neither CPB temperature nor Leumedin affected N-margination significantly.

Osseous manifestations of bacillary angiomatosis.

We report a case of bacillary angiomatosis in a 32-year-old HIV-positive black Haitian male. Radiologic and pathologic features are presented.

Efficient parathyroidectomy guided by SPECT-MIBI and hormonal measurements.

UNLABELLED: Parathyroidectomy is a difficult and lengthy operation which is noncurative in 6% to 10% of cases. To improve the efficiency of this operation, a new dual diagnostic approach was prospectively applied. METHODS: Preoperative tomographic 99mTc-sestamibi (MIBI) scintography and intraoperative measurements of circulating parathyroid hormone (PTH) levels by a quick assay (QPTH) were used. Scintigraphy comprised immediate and delayed planar and SPECT of the neck and chest, following 20 mCi MIBI. The presence and location of persistent foci of abnormal activity found within the neck mediastinum on volume-rendered reprojection (RPJ) of the SPECT data were reported. The surgion, guided by the three-dimensional MIBI-SPECT/RPJ images, identified and excised the single or most prominent scintigraphic focus and applied the QPTH. If PTH levels fell from baseline by at least 50%, the operation was concluded. RESULTS: The operative time of primary parathyroidectomy was reduced from an average of 90 min (before the introduction of scintigraphy and intraoperative PTH measurements) to 57 min. All but two patients became normocalcemic. In 58 consecutive patients with hyperparathyroidism, MIBI-SPECT/RPJ correctly and precisely identified 51 of 53 (96%) primary parathyroid adenomas, 14 to 15 secondary hyperplasias and 2 of 3 hyperplastic glands in MEN (sensitivity 94%, specificity 92%). QPTH verified the excision of the primary parathyroid adenomas and predicted normocalcemia in 50 of 52 patients. In 6 patients with misleading scintigraphy, QPTH was especially useful and guided the surgeon to continue the operation until the abnormal parathyroid tissue was found and excised. CONCLUSION: MIBI-SPEC/RPJ and QPTH sequentially applied improved the efficiency of parathyroidectomy.

Surveillance imaging in children with primitive neuroectodermal tumors.

Controversy surrounds the benefits of routine surveillance magnetic resonance or computed tomographic imaging for monitoring children after resection of primitive neuroectodermal tumors. A recent study suggested that serial imaging studies detect only a small minority of tumor recurrences in patients with symptoms. The authors concluded that even in patients with recurrence documented by imaging, no patient with a recurrence survived long (average, 5 mo) and that surveillance scanning is of little clinical value in children with primitive neuroectodermal tumors. We reviewed our experience with 25 patients (28% of our total series) who presented to the Children's Hospital Los Angeles, Los Angeles, CA, from 1985 to 1993 with recurrent tumors after surgery and adjuvant therapy. Recurrent tumors were detected on routine imaging in 19 asymptomatic patients (76%) and in 6 symptomatic patients (24%). Recurrences were documented 15 months (mean) after the initial diagnosis in asymptomatic children and 5 months (mean) after the initial diagnosis in children with symptoms of recurrent tumor (P < or = 0.01). Asymptomatic patients with recurrence documented on serial imaging had prolonged survival when compared with those who were symptomatic (P < or = 0.05). The surviving patients with recurrence remained alive for more than 24 months after documentation of recurrence. Early detection of local tumor recurrence by surveillance scanning may provide a critical therapeutic window for successful treatment with aggressive or novel therapies.

Role of nuclear medicine and AIDS: overview and perspective for the future.

The Human Immunodeficiency Virus (HIV) is the causative agent for the expanding epidemic of the Acquired Immunodeficiency Syndrome (AIDS). Sixteen million individuals were estimated to be infected worldwide with HIV by the World Health Organization in 1995, with over 10 million in Africa and one million in the USA. As the HIV cost in dollars and lives continues to rise it will become more important to understand AIDS and to foresee the potential role of nuclear medicine in HIV diseases. Nuclear medicine may have a role in the assessment of immune function, including the ability to predict if individuals can avoid progression to HIV+status, if pre-AIDS to AIDS conversion can be prevented, and if an individual's immune status requires addition of prophylaxis. Also it can be used for disease detection at an early stage and determination of the extent of disease. It is especially useful to assist clinicians in optimizing therapy and assessing its efficacy. In the future new radiopharmaceuticals for detecting a specific infections and tumors will be needed. This will require collaborative efforts with basic scientists and clinicians working hand in hand to address specific issues related to AIDS.

Inflammatory and infectious processes of the cervical spine.

This article discusses infectious and inflammatory processes of the cervical spine. Major emphasis is placed on infectious discitis/osteomyelitis and epidural abscess, particularly the epidemiologic, bacteriologic, pathophysiologic, and clinical aspects, as well as the major role played by magnetic resonance imaging and other imaging modalities used in the detection and diagnosis of these processes.

Absence of lethal reperfusion injury after 3 hours of reperfusion. A study in a single-canine-heart model of ischemia-reperfusion.

BACKGROUND: Whether reperfusion can cause necrosis of previously viable myocytes (lethal reperfusion injury) remains controversial. Numerous studies examined the ability of various agents to prevent or limit reperfusion injury, but the results were contradictory. In a single-canine-heart model of ischemia-reperfusion, we previously demonstrated that 5 minutes of reperfusion does not increase the transmural extent of necrosis. Since the 5-minute period of reperfusion is considered by some to be too short for the full manifestation of reperfusion injury, we reexamined the issue of lethal reperfusion injury using a modification of the single-heart model of ischemia-reperfusion that allowed extending the reperfusion period to 3 hours. METHODS AND RESULTS: In anesthetized, open-chest dogs, the distal half of the left anterior descending coronary artery (LAD) segment between the last diagonal branch and the apex was perfused via a shunt from the left carotid artery. The shunt was closed for periods of 90 to 180 minutes, depending on the ECG severity of ischemia, and reperfused for 3 hours. While the distal region was perfused from the carotid artery, the LAD was occluded proximal to the last diagonal branch for the same period of time as the distal region had been earlier. The time of occlusion was chosen such that the end of the occlusion period coincided with the end of the experiment. Thus, both regions of the LAD territory were subjected to identical periods of ischemia, but only the distal region was reperfused. At the end of the experiment, the boundary between the proximal (nonreperfused) and distal (reperfused) area was delineated by blue dye, and the heart was arrested, cut into slices 1 cm thick parallel to the LAD, and placed in triphenyltetrazolium chloride. The epicardial edges of necrosis in the reperfused and the nonreperfused regions were examined for any shift that might suggest a difference in the transmurality of necrosis. The areas of necrotic and viable myocardium were measured by planimetry within 1 cm on either side of the boundary. In all 14 dogs, the epicardial edges of necrosis ran as a single line across the boundary, and no shift was present. There was also no difference in the transmurality of necrosis between the reperfused and nonreperfused regions (64.9 +/- 20.7% versus 66.1 +/- 17.0% of left ventricular wall thickness, respectively, P = .32 by paired t test). CONCLUSIONS: In a single-canine-heart model of ischemia-reperfusion, there was no evidence of lethal reperfusion injury after 3 hours of reperfusion.

Cardiovascular magnetic resonance imaging goes beyond anatomy.

Magnetic resonance imaging (MRI) provides noninvasive functional information as well as a three-dimensional anatomic display of the cardiovascular system. MRI of protons, phosphorus, or sodium nuclei is currently being investigated to characterize cardiovascular pathology, and the potential benefits of paramagnetic contrast agents are becoming apparent. Finally, techniques to quantitate blood flow, vascular pressures, chamber volumes, ventricular ejection fractions, and cardiac output are being developed.

Use of thallium-201 brain SPECT to differentiate cerebral lymphoma from toxoplasma encephalitis in AIDS patients.

PURPOSE: To determine whether thallium-201 brain single-photon emission CT could be used to make the distinction between central nervous system lymphoma and toxoplasma encephalitis, which may not be possible by routine MR and CT. METHODS: A total of 37 patients with acquired immunodeficiency syndrome who had intracranial mass lesions found during a 9-month prospective study by either MR or CT underwent further evaluation with Tl-201 brain single-photon emission CT. RESULTS: Twelve patients had increased intense focal Tl-201 uptake. All of these patients had either biopsy- or autopsy-proven lymphoma. Twenty-five of the patients studied had no Tl-201 brain uptake in the lesion(s); 24 of these patients had toxoplasma encephalitis on clinical follow-up. One patient with no Tl-201 uptake was found by cerebrospinal fluid analysis to have mycobacterium tuberculosis abscess. CONCLUSION: Patients with acquired immunodeficiency syndrome who have intracranial mass lesions on MR or CT may benefit from Tl-201 brain single-photon emission CT because it can help distinguish between lymphoma and infectious lesions such as toxoplasma encephalitis.

99mTc-HMPAO SPECT of the brain in mild to moderate traumatic brain injury patients: compared with CT--a prospective study.

Single photon emission computed tomography (SPECT) with Technetium-99m hexamethyl propylenamine oxime (Tc-99m-HMPAO) was used in 20 patients with mild to moderate traumatic brain injury (TBI) to evaluate the effects of brain trauma on regional cerebral blood flow (rCBF). SPECT scan was compared with CT scan in 16 patients. SPECT showed intraparenchymal differences in rCBF more often than lesions diagnosed with CT scans (87.5% vs. 37.5%). In five of six patients with lesions in both modalities, the area of involvement was relatively larger on SPECT scans than on CT scans. Contrecoup changes were seen in five patients on SPECT alone, two patients with CT alone and one patient had contrecoup lesions on CT and SPECT. Of the eight patients (50%) with skull fractures, seven (43.7%) had rCBF findings on SPECT scan and five (31.3%) demonstrated decrease in rCBF in brain underlying the fracture. All these patients with fractures had normal brain on CT scans. Conversely, extra-axial lesions and fractures evident on CT did not visualize on SPECT, but SPECT demonstrated associated changes in rCBF. Although there is still lack of clinical and pathological correlation, SPECT appears to be a promising method for a more sensitive evaluation of axial lesions in patients with mild to moderate TBI.

Detection of early anthracycline cardiotoxicity by monitoring the peak filling rate.

Three patients developed clinical congestive heart failure after cumulative doxorubicin doses of 264, 440, and 450 mg/m2, respectively, despite serial monitoring of systolic cardiac function by resting gated radionuclide scanning. All three patients had depressed diastolic function, as shown by a decreased peak filling rate preceding a change in systolic function, which was assessed by left ventricular ejection fraction prior to the development of clinical congestive heart failure. We recommend serial monitoring of the peak filling rate, in addition to left ventricular ejection fraction. If broader experience confirms our impression that the peak filling rate is more sensitive than the current standard assessment of left ventricular ejection fraction, new guidelines may need to be drawn to monitor cardiotoxicity of anthracyclines and anthraquinones.

Angiographic validation of bedside markers of reperfusion.

OBJECTIVES: We sought to validate with coronary angiography several primary and ancillary markers of reperfusion. BACKGROUND: The availability of bedside markers of reperfusion is of major importance in the thrombolytic therapy of acute myocardial infarction. However, the reliability of current markers is still controversial. METHODS: Changes in chest pain, ST segment elevation and heart rate and rhythm were assessed every 5 to 10 min for up to 3 h after initiation of recombinant tissue-type plasminogen activator therapy in 82 patients with acute myocardial infarction. Coronary angiography was performed within 24 h. RESULTS: At angiography, 69 of the 82 patients had a patent infarct-related artery with Thrombolysis in Myocardial Infarction trial (TIMI) grade 3 flow and a rapid and progressive decrease in chest pain and ST elevation. The pain resolved in 24 +/- 23 min (range 3 to 50). The ST elevation decreased by > or = 50% within 16 +/- 14 min (range 5 to 41). Accelerated idioventricular rhythm developed in 49% of patients and sinus bradycardia in 23%; conduction abnormalities and atrial fibrillation resolved. All markers appeared in close temporal proximity to the onset of an abrupt increase in plasma creatine kinase (CK) and CK-MB isoenzyme activity, a previously validated marker of the time of reperfusion. Before its final resolution, ST elevation transiently decreased and increased in 58% of patients. Comparison of one pretreatment and one posttreatment electrocardiogram significantly reduced the reliability of ST segment change as a marker of reperfusion. In 13 of 82 patients, the infarct-related artery demonstrated TIMI grade < or = 2 flow; in 9, pain and ST elevation did not lessen and CK and CK-MB activity showed no abrupt increase. The remaining four patients initially demonstrated a decrease in pain and ST elevation; however, within 3 h and before angiography, the recurrence of pain and ST elevation suggested reocclusion. CONCLUSIONS: A rapid and progressive decrease in pain and ST elevation is a reliable marker of reperfusion with TIMI grade 3 flow. Because ST elevation and pain often fluctuate before undergoing final resolution with reperfusion, frequent or continuous monitoring of ST elevation is essential for reliable recognition of the fact and time of reperfusion. Accelerated idioventricular rhythm and episodes of sudden sinus bradycardia, although specific to reperfusion, do not occur in all patients with reperfusion.

Indium 111-labeled leukocyte scintigraphy in evaluating head and neck infections.

This retrospective study looked at the role of indium 111-labeled white blood cell (111In WBC) scintigraphy in head and neck infections. The efficacy of 111In WBCs was compared to gallium 67 citrate (67Ga) and technetium Tc99m methylene diphosphonate (99mTc MDP) scintigraphy in detecting and monitoring the resolution of infection. For 22 active infections, the sensitivities for 111In WBC, 67Ga, and 99mTc MDP scintigraphy were 94%, 56%, and 86%, respectively, and the specificities for 111In WBC, 67Ga, and 99mTc MDP scintigraphy were 100%, 43%, and 0%, respectively. For 8 successfully treated infections, all seven 111In WBC studies became negative after therapy, in as short an interval as 1 month. In contrast, all seven 99mTc MDP images remained positive for as long as 6 months after therapy. The seven 67Ga studies had variable results, with four (57%) remaining positive, including two (28%) positive at 6 months after therapy. These results suggest that 111In WBC scintigraphy should be the initial radionuclide imaging tool in detecting active head and neck infections because of its greater accuracy, and its ability to revert to normal much sooner than 67Ga or 99mTc MDP scintigraphs when applied to a subset of patients with resolved infections.