Emerging role of Fluorine-18-fluorodeoxyglucose positron emission tomography in patients with retroperitoneal fibrosis: a systematic review

To systematically review the literature data on the role of Fluorine-18-fluorodeoxyglucose positron emission tomography and positron emission tomography/computed tomography (FDG-PET and PET/CT) in patients with retroperitoneal fibrosis (RF), PubMed/MEDLINE, Embase and Scopus databases were searched for articles that evaluated the usefulness of FDG-PET and PET/CT in patients with RF from inception to March 31, 2012. Review articles or editorials, articles not in the field of interest of this review, case reports and preclinical studies were excluded. Only studies including FDG-PET or PET/CT scans performed in at least three patients with RF were included. Ten studies comprising a total of 101 patients with RF were found. The main findings of the included studies are described. FDG-PET and PET/CT are feasible and suitable imaging methods for evaluating patients with RF. These functional imaging techniques seem to be useful both in the diagnosis (mainly in the assessment of activity and extent of the disease) and in evaluating the treatment response in patients with RF. Given the heterogeneity among the various studies for PET analysis and diagnostic criteria, a standardization of the technique is required in order to achieve reproducible and inter-observer independent results. Moreover, further studies are needed to substantiate the role of FDG-PET and PET/CT in patients with RF.     

The role of spiral volumetric computed tomography in the diagnosis of pulmonary embolism

To evaluate the evidence for the use of spiral volumetric computed tomography (SVCT) in the diagnosis of acute pulmonary embolism (PE), the 11 English-language studies published through July 1998 that compared SVCT with a reference standard for PE were systematically reviewed. Among the reviewed studies, methodological problems were common. Only 5 of these studies fulfilled 5 of 11 basic standards addressing important issues in diagnostic test research. The reported sensitivities of SVCT compared with pulmonary angiography varied widely (64%-93%), which was likely the result of differences in study populations. Spiral volumetric computed tomography may be relatively sensitive and specific for diagnosing central pulmonary artery PEs, but it is insensitive for diagnosing subsegmental clots. Spiral volumetric computed tomography may have a role as a "rule-in" test for large central emboli, but additional research is required to establish its place in clinical practice.     

Multislice spiral computed tomography in diagnosis and staging of pancreatic carcinoma: preliminary experience

BACKGROUND: Computed tomography has become the modality of choice for preoperative evaluation of patients with suspected pancreatic carcinoma, although some limitations are well known. AIMS: To evaluate use of multislice spiral computed tomography in preoperative assessment of patients with suspected pancreatic carcinoma using volume-rendering as image reconstruction algorithm. PATIENTS: A total of 27 patients with suspected pancreatic carcinoma underwent multislice spiral computed tomography examination. METHODS: All studies were performed on a multislice computed tomography scanner with the following parameters: slice collimation, 1 mm; slice thickness, 1.25 mm; reconstruction interval, 1 mm; scan time, 22-25 sec; mAs, 165. Scans were acquired with a biphasic technique with a 30-sec (pancreatic phase) and a 70-sec (portal venous phase) delay time after start of contrast material injection. Diagnostic confirmation was obtained with surgical exploration, percutaneous biopsy, or with a combination of follow-up imaging studies. RESULTS: Multislice spiral computed tomography yielded correct diagnosis of pancreatic carcinoma in 20 cases (sensitivity, 95%; specificity, 100%). Positive predictive values for resectability and unresectability were 80% and 93.3%, respectively. Three-dimensional volume-rendered images improved diagnostic confidence in the depiction of major vascular structures. Two cases of anomalous origin of hepatic artery were also identified with volume-rendered images. CONCLUSIONS: Multislice technology improves accuracy of spiral computed tomography for diagnosis and staging of pancreatic carcinoma.     

Diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography in the follow-up of papillary or follicular thyroid cancer

Positron emission tomography with 18F-fluorodeoxyglucose is a relatively new nuclear imaging technique in oncology. We conducted a systematic review to determine the diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography in patients suspected of recurrent papillary or follicular thyroid carcinoma. Two reviewers independently selected, extracted, and assessed data from relevant literature found in computerized databases and by reference tracking. Prospective and retrospective studies with 10 human subjects, or more, that evaluated the accuracy of ring positron emission tomography, using 18F-fluorodeoxyglucose in follicular and papillary thyroid cancer, were included. Studies on 18F-fluorodeoxyglucose imaging using gamma cameras, reviews, case reports, editorials, letters, and comments were excluded. The methodological quality was assessed by applying the criteria for diagnostic tests recommended by the Cochrane Methods Group on Screening and Diagnostic Tests. A rating system was used for qualitative analysis consisting of four levels of evidence (1 = highest level; 4 = lowest level). Fourteen studies met the inclusion criteria. All studies claimed a positive role for positron emission tomography but, at evidence levels 3 or 4, precluding quantitative analysis. Methodological problems included poor validity of reference tests and a lack of blinding of test performance and interpretation. The reviewed material was heterogeneous with respect to patient variation and validation methodology. The most consistent data were found on the ability of 18F-fluorodeoxyglucose positron emission tomography to provide an anatomical substrate in patients with elevated serum Tg and negative iodine-131 scans. In conclusion, the results seem to support the potential of 18F-fluorodeoxyglucose positron emission tomography to identify and localize foci of recurrent cancer in the latter patient subset. However, implementation of positron emission tomography in a routine diagnostic algorithm requires additional evidence.     

Usefulness of FDG-PET scan in the assessment of suspected metastatic or recurrent adenocarcinoma of the colon and rectum

PURPOSE: The purpose of this study was to evaluate the clinical efficacy of positron emission tomography with 2-[¹⁸F] fluoro-2-deoxy-D-glucose compared with computed tomography plus other conventional diagnostic studies in patients suspected of having metastatic or recurrent colorectal adenocarcinoma. METHODS: The records of 105 patients who underwent 101 computed tomography and 109 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography scans for suspected metastatic or recurrent colorectal adenocarcinoma were reviewed. Clinical correlation was confirmed at time of operation, histopathologically, or by clinical course. RESULTS: The overall sensitivity and specificity of 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography in detection of clinically relevant tumor were higher (87 and 68 percent) than for computed tomography plus other conventional diagnostic studies (66 and 59 percent). The sensitivity of 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography in detecting mucinous cancer was lower (58 percent; n=16) than for nonmucinous cancer (92 percent; n=93). The sensitivity of 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography in detecting locoregional recurrence (n=70) was higher than for computed tomography plus colonoscopy (90vs. 71 percent, respectively). The sensitivity of 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography in detecting hepatic metastasis (n=101) was higher than for computed tomography (89vs. 71 percent). The sensitivity of 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography in detecting extrahepatic metastases exclusive of locoregional recurrence (n=101) was higher than for computed tomography plus other conventional diagnostic studies (94vs. 67 percent). 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography altered clinical management in a beneficial manner in 26 percent of cases (26/101) when compared with evaluation by computed tomography plus other conventional diagnostic studies. CONCLUSION: 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography is more sensitive than computed tomography for the detection of metastatic or recurrent colorectal cancer and may improve clinical management in one-quarter of cases. However, 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography is not as sensitive in detecting mucinous adenocarcinoma, possibly because of the relative hypocellularity of these tumors.Dr. H. M. Whiteford was supported by the Wallace R. Ruwitch Family Research Fund.Read at The American Society of Colon and Rectal Surgeons' 100th Anniversary and Tripartite Meeting, Washington, DC, May 1 to 6 1999.     

Prognostic value of echocardiography and spiral computed tomography in patients with pulmonary embolism

PURPOSE OF REVIEW: The identification of patients with pulmonary embolism who are at risk for mortality or severe morbidity in the early observation period is important because these patients may benefit from more aggressive initial treatment such as thrombolysis or catheter removal of the thrombus. Right ventricular dysfunction has been suggested to have a prognostic value for the occurrence of these adverse outcomes. The purpose of this review is to determine the prevalence and prognostic value of right ventricular dysfunction, in particular in normotensive patients with pulmonary embolism. The association between right ventricular dysfunction and outcome of pulmonary embolism was evaluated for studies using echocardiography, spiral computed tomography, or both to detect right ventricular dysfunction. RECENT FINDINGS: Seven studies using echocardiography with a total of 3468 patients and six studies using spiral computed tomography with a total of 868 patients were identified. The prevalence of right ventricular dysfunction with echocardiography in normotensive patients was approximately 30 to 40%, with a positive predictive value for short-term mortality of approximately 5%. These indices could not be calculated for normotensive patients in the studies that used spiral computed tomography. SUMMARY: The studies using echocardiography show that there is an association between right ventricular dysfunction and prognosis of pulmonary embolism in normotensive patients. Whether this is clinically useful in guiding more aggressive therapy remains to be determined, however. Thus far, the results of the studies with spiral computed tomography are too preliminary to enable definite conclusions to be drawn for the normotensive patient group.     

Pulmonary involvement in ankylosing spondylitis

PURPOSE OF REVIEW: Anti-tumor necrosis factor-alpha agents have recently been approved and recommended as effective and relatively safe drug therapy for ankylosing spondylitis. In light of this major advance in the management of these patients, recent observations on the pulmonary manifestations of ankylosing spondylitis are reviewed. RECENT FINDINGS: High-resolution computed tomography abnormalities were found to be prevalent (range 50-85%) in ankylosing spondylitis even in patients with early disease, and in those with normal chest radiographs and without respiratory symptoms. The high-resolution computed tomography changes included apical fibrosis, interstitial lung disease, emphysema, bronchietasis and pleural thickening. In general, the high-resolution computed tomography changes were of mild degree, and no correlation was observed between high-resolution computed tomography abnormalities, pulmonary function test variables and indices of ankylosing spondylitis symptoms and disease structural severity. Spontaneous pneumothorax was reported to be a rare complication, but tended to occur in those patients with fibrobullous disease. SUMMARY: The clinical significance of the high-resolution computed tomography abnormalities remains to be determined. Most of the published studies are cross-sectional, and are limited by lack of control subjects matched for age, gender and tobacco use. Studies to correlate high-resolution computed tomography changes with bronchoalveolar lavage and lung biopsies as well as prospective studies on long-term evolution of these findings including those patients receiving anti-tumor necrosis factor-alpha agents are needed.     

Important Advances in Technology and Unique Applications to Cardiovascular Computed Tomography

For the past decade, multidetector cardiac computed tomography and its main application, coronary computed tomography angiography, have been established as a noninvasive technique for anatomical assessment of coronary arteries. This new era of coronary artery evaluation by coronary computed tomography angiography has arisen from the rapid advancement in computed tomography technology, which has led to massive diagnostic and prognostic clinical studies in various patient populations. This article gives a brief overview of current multidetector cardiac computed tomography systems, developing cardiac computed tomography technologies in both hardware and software fields, innovative radiation exposure reduction measures, multidetector cardiac computed tomography functional studies, and their newer clinical applications beyond coronary computed tomography angiography.     

Screening for lung cancer

The National Lung Screening Study has demonstrated that screening with low-dose spiral computed tomography results in fewer deaths from lung cancer compared with screening with chest radiography (CXR). Previous trials of screening with CXR and sputum cytology failed to exhibit fewer deaths compared with no screening intervention. Early computed tomography (CT) studies showed promise for CT to be a more sensitive test, yet were unable to demonstrate sufficient evidence of efficacy. This review examines the problem of early lung cancer detection, the issues presented by screening, and results of past and recent studies of lung cancer screening.     

Comprehensive noninvasive evaluation of left atrial myxomas using cardiac cine-computed tomography

This report describes the first clinical experience with ultrafast (cine) computed tomography for evaluating intracardiac masses. Two patients had a left atrial myxoma that was comprehensively described (size, location, site of attachment and relation to the mitral valve) preoperatively by cine-computed tomography. The information content of the studies exceeded that of two-dimensional echocardiography, and both patients were operated on without invasive cardiac catheterization. This early experience with a new minimally invasive high temporal and spatial resolution technology suggests that cine-computed tomography may be uniquely suited for precise evaluation of intraatrial masses.     

Magnetic resonance imaging of the brain and spine. Is clinical efficacy established after the first decade?

STUDY OBJECTIVE: Evaluation of demonstrated clinical efficacy of magnetic resonance (MR) imaging in the central nervous system. DESIGN: Information synthesis of studies before January 1987. SETTING: Reports were classified by the level of clinical efficacy studied (technical capacity, diagnostic impacts, and therapeutic or patient outcome impacts) and were judged by the validity of their methods, especially avoidance of diagnosis review, test review, and work-up biases. MAIN RESULTS: Magnetic resonance imaging probably is superior to computed tomography for detection and characterization of posterior fossa lesions and spinal cord myelopathies, imaging in multiple sclerosis, detecting lesions in patients with refractory partial seizures, and detailed display for guiding complex therapy, as for brain tumors. In other diseases, the efficacy of MR imaging is similar to that of computed tomography (cerebrovascular, radiculopathy, and infection). Magnetic resonance imaging is less invasive than intrathecal or intravenous contrast-enhanced computed tomography and costs 20% to 300% more than computed tomography, although avoidance of hospital stays may offset some costs. Generally, the quality of MR images probably exceeds that of computed tomographic (CT) scans. However, published evidence does not show that the clinical efficacy of MR imaging is generally superior to that of existing imaging modalities such as computed tomography. Only six studies avoided major methodologic biases, and lower true-positive rates for MR imaging were reported in these studies than reported in multiply biased studies. Few studies of the potential of MR imaging for false-positive diagnosis have been done. CONCLUSIONS: Use of standards for quality of evidence leads to more conservative conclusions than those of reports describing the clinical potential of MR imaging. Some applications of MR imaging were confirmed by rigorous studies, whereas others were not well supported by reports free of methodologic biases. If the diagnostic alternative is invasive (for example, myelography and cisternography), MR imaging is preferred, but adequate diagnosis for many conditions (head trauma, simple stroke, and dementia) may not require the detail of an MR imaging study. In general, more rigorous clinical research studies are needed for new technologies such as MR imaging. Because the field of MR imaging is changing, review of its clinical efficacy will need to be revised frequently.     

Positron emission tomography/computed tomography surveillance in patients with Hodgkin lymphoma in first remission has a low positive predictive value and high costs

Background

The value of performing post-therapy routine surveillance imaging in patients with Hodgkin lymphoma is controversial. This study evaluates the utility of positron emission tomography/computed tomography using 2-[18F]fluoro-2-deoxyglucose for this purpose and in situations with suspected lymphoma relapse.

Design and Methods

We conducted a multicenter retrospective study. Patients with newly diagnosed Hodgkin lymphoma achieving at least a partial remission on first-line therapy were eligible if they received positron emission tomography/computed tomography surveillance during follow-up. Two types of imaging surveillance were analyzed: “routine” when patients showed no signs of relapse at referral to positron emission tomography/computed tomography, and “clinically indicated” when recurrence was suspected.

Results

A total of 211 routine and 88 clinically indicated positron emission tomography/computed tomography studies were performed in 161 patients. In ten of 22 patients with recurrence of Hodgkin lymphoma, routine imaging surveillance was the primary tool for the diagnosis of the relapse. Extranodal disease, interim positron emission tomography-positive lesions and positron emission tomography activity at response evaluation were all associated with a positron emission tomography/computed tomography-diagnosed preclinical relapse. The true positive rates of routine and clinically indicated imaging were 5% and 13%, respectively (P=0.02). The overall positive predictive value and negative predictive value of positron emission tomography/computed tomography were 28% and 100%, respectively. The estimated cost per routine imaging diagnosed relapse was US$ 50,778.

Conclusions

Negative positron emission tomography/computed tomography reliably rules out a relapse. The high false positive rate is, however, an important limitation and a confirmatory biopsy is mandatory for the diagnosis of a relapse. With no proven survival benefit for patients with a pre-clinically diagnosed relapse, the high costs and low positive predictive value make positron emission tomography/computed tomography unsuitable for routine surveillance of patients with Hodgkin lymphoma.     

Prognostic role of single-photon emission computed tomography (SPECT) imaging in myocardial viability

PURPOSE OF REVIEW: Cardiac imaging is evolving rapidly. Appropriate use of this technology could reduce morbidity and mortality, but inappropriate use could have a significant financial burden. Single-photon emission computed tomography imaging is widely available. This review summarizes the clinical utility and limitations of the prognostic role of single-photon emission computed tomography imaging for myocardial viability in patients with coronary artery disease and left-ventricular dysfunction. RECENT FINDINGS: 201Tl single-photon emission computed tomography, 99mTc single-photon emission computed tomography with sestamibi or tetrofosmin, and 18F-fluorodeoxyglucose single-photon emission computed tomography are validated tools for assessing myocardial viability. These techniques have a very similar predictive value in determining regional and global response to revascularization. 201Tl single-photon emission computed tomography viability studies are predictive of reverse left-ventricular remodeling, symptom improvement, and patient outcome after revascularization. Combination imaging with dual-isotope simultaneous acquisition single-photon emission computed tomography or positron-emission tomography/single-photon emission computed tomography may improve the positive and negative predictive values of single-photon emission computed tomography-based viability studies. SUMMARY: Single-photon emission computed tomography-based myocardial viability testing is an important diagnostic modality due to widespread availability and reasonably good sensitivity and specificity for detecting viable myocardium and predicting clinical and functional responses to revascularization. In the future single-photon emission computed tomography viability techniques may have a prognostic role in predicting responses to cardiac resynchronization therapy and evaluating myocardial stem-cell transplantation.     

Quantitative computed tomography assessment of lung structure and function in pulmonary emphysema.

Accurate diagnosis and quantification of pulmonary emphysema during life is important to understand the natural history of the disease, to assess the extent of the disease, and to evaluate and follow-up therapeutic interventions. Since pulmonary emphysema is defined through pathological criteria, new methods of diagnosis and quantification should be validated by comparisons against histological references. Recent studies have addressed the capability of computed tomography (CT) to quantify pulmonary emphysema accurately. The studies reviewed in this article have been based on CT scans obtained after deep inspiration or expiration, on subjective visual grading and on objective measurements of attenuation values. Especially dedicated software was used for this purpose, which provided numerical data, on both two- and three-dimensional approaches, and compared CT data with pulmonary function tests. More recently, fractal and textural analyses were applied to computed tomography scans to assess the presence, the extent, and the types of emphysema. Quantitative computed tomography has already been used in patient selection for surgical treatment of pulmonary emphysema and in pharmacotherapeutical trials. However, despite numerous and extensive studies, this technique has not yet been standardized and important questions about how best to use computed tomography for the quantification of pulmonary emphysema are still unsolved.     

Correlating computed tomography and positron emission tomography scan with operative findings in metastatic colorectal cancer

INTRODUCTION: Several studies have been performed comparing computed tomography scan with positron emission tomography scan in clinical decision making. Unfortunately, therapeutic decisions are being made based on positron emission tomography scan data without a clear understanding of how well the diagnostic findings correlate with the clinical findings. METHODS: A retrospective review of 41 patients with metastatic colorectal cancer was performed. All patients had both a computed tomography scan and a positron emission tomography scan before surgical exploration. All underwent surgical re-exploration. Findings were divided into hepatic, extrahepatic, and pelvic regions of the abdomen. Computed tomography scan and positron emission tomography scan findings were either confirmed or refuted by the operative findings. RESULTS: Positron emission tomography scan was found to be more sensitive than computed tomography scan when compared with actual operative findings in the liver (100vs. 69 percent,P=0.004), extrahepatic region (90vs. 52 percent,P=0.015), and abdomen as a whole (87vs. 61 percent,P<0.001). Sensitivities of positron emission tomography scan and computed tomography scan were not significantly different in the pelvic region (87vs. 61 percent,P=0.091). In each case, specificity was not significantly different between the two examinations. CONCLUSION: Computed tomography scan and positron emission tomography scan are both diagnostic tests useful in the evaluation of metastatic colorectal cancer. However, positron emission tomography scanning is more sensitive than computed tomography scanning and more likely to give the correct result when actual metastatic disease is present.     

急性卒中缺血半暗带的CT灌注成像

CT灌注成像能准确和及时地提供卒中后脑组织血流动力学参数,并且与当前公认的脑血流动力学测量手段——氙-CT、功能磁共振成像和正电子发射体层摄影等测得的参数有很好的相关性。因此,CT灌注成像在判断卒中后缺血半暗带研究中的应用日益广泛。     

Detection of coronary artery stenosis using 40-channel computed tomography with multi-segment reconstruction

Coronary angiographic studies performed with 16-channel multidetector computer tomographic scanners have demonstrated accurate detection of coronary vessel stenosis but are limited by a significant number of non-evaluable segments. To date, only single-center experience with multidetector computer tomography has been reported. We performed a prospective, blinded study at 2 institutions to determine the feasibility and diagnostic accuracy of coronary angiography using 40-channel multidetector computer tomography with multi-segment reconstruction for the detection of obstructive coronary artery disease (CAD). Multidetector computer tomographic studies were performed in 85 patients who were referred for invasive coronary angiography with clinically suspected CAD. Datasets were analyzed by blinded, independent review. Of 1,145 segments that were suitable for analysis as determined by angiography, 1,045 (91.3%) were evaluable on multidetector computer tomography. Segment-based sensitivity, specificity, and positive and negative predictive values for detecting > or =50% luminal stenoses were 86%, 97%, 75%, and 97%, respectively. The area under the receiver-operating characteristic curves for the detection of > or =50% angiographic stenosis by multidetector computer tomography was 0.94. In a patient-based analysis, the sensitivity, specificity, and positive and negative predictive values for detecting subjects with > or =1 segment with > or =50% stenosis were 98%, 93%, 94% and 93%, respectively. In conclusion, coronary angiography using 40-channel multidetector computer tomography with multi-segment reconstruction accurately detects coronary segments and patients with obstructive CAD, with a small number of non-evaluable cases.     

Prevalence of misregistration between SPECT and CT for attenuation-corrected myocardial perfusion SPECT.

BACKGROUND: Nonuniform attenuation artifacts may reduce the diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) studies. Compensation strategies using an attenuation map (eg, from x-ray tomography) have been reported to improve accuracy. Because the computed tomography (CT) and SPECT images are obtained sequentially, misregistration of the emission and transmission scans can occur. Our objective was to qualitatively assess these misregistration errors. METHODS AND RESULTS: This study included 60 patients who consecutively underwent CT attenuation-corrected myocardial perfusion studies acquired on a SPECT/CT system equipped with a nondiagnostic CT scanner. The cardiac SPECT/CT and fused images were reviewed and qualitatively assessed for misregistration of the heart between the CT and emission image data sets. The degree of misregistration was qualitatively rated on a 5-point scale. Misregistration was judged to be none in 4 of 55 patients, minimal in 9, mild in 19, moderate in 21, and severe in 2 patients. Five studies could not be assessed because of severe artifacts on CT. CONCLUSIONS: Forty-two percent of the CT attenuation-corrected myocardial perfusion studies had moderate to severe cardiac misregistration qualitatively. Our data suggest that careful review of attenuation correction maps and registration is needed to avoid reconstruction artifacts due to misregistration.     

Computed tomography of coronary arteries

The review covers possibilities of modern techniques of computer tomography (CT) of coronary arteries: electron beam tomography and 4-, 16-, 64-slice multi-spiral CT. Main studies conducted in this area are analyzed. Results of these studies (values of sensitivity and specificity, numbers of included patients, numbers of segments of coronary arteries which were excluded from analysis because of poor quality of images) are presented and compared. Problems of further development of CT of coronary arteries are also considered.     

Understanding the heart: CT and MRI for coronary heart disease

Methods of noninvasive evaluation of coronary artery disease-including multidetector row computed tomography, electron beam computed tomography, magnetic resonance imaging, and nuclear studies (single photon emission computed tomography, positron emission tomography)-are reviewed.