Multiple diagnostic task performance in CT examination of the chest.

OBJECTIVES: In three experiments, we studied the detection of multiple abnormality types using the satisfaction of search (SOS) paradigm, the provision of a computer-aided detection (CAD) of pulmonary nodules and a focused nodule detection task. METHODS: 51 chest CT examinations (24 that demonstrated subtle pulmonary nodules and 27 that demonstrated no pulmonary nodules) were read by 15 radiology residents and fellows under two experimental conditions: (1) when there were no other abnormalities present except test abnormalities in the exams (non-SOS condition), and (2) when other abnormalities were present in the exams (SOS condition). Trials from the two conditions were intermixed. Readers were invited to return for two sessions: one in which the SOS condition was repeated with a simulated CAD; another in which only the non-SOS condition was presented. Detection accuracy was measured using receiver operating characteristic (ROC) analysis. RESULTS: An SOS effect (reduced detection accuracy for the test nodules in the presence of the diverse added abnormalities) was not found. Average accuracy was much higher when the CAD prompt was provided, without cost in the detection of the added abnormalities. Accuracy for detecting nodules appearing without intermixed SOS trials was also substantially improved. CONCLUSIONS: CT interpretation was highly task dependent. Nodule detection was poor in the general search task. Therefore, CAD may offer a greater performance improvement than demonstrated in experiments assessing CAD using focused search. The absence of SOS may be due to limited nodule detection even without other abnormalities. Advances in knowledge CAD prompts of nodules increase the detection accuracy of nodules and decrease the time to detection-without impairing the detection accuracy-of non-nodule abnormalities.

Factors influencing visualization of vertebral metastases on MR imaging versus bone scintigraphy.

OBJECTIVE: The purpose of this study was to investigate whether the location and size of vertebral body metastases influence the difference in detection rates between MR imaging and bone scintigraphy. MATERIALS AND METHODS: We retrospectively evaluated the vertebral body lesions detected on MR imaging in 74 patients with known widely disseminated metastatic disease. Three radiologists independently reviewed the MR images and bone scintigraphs. MR imaging findings included lesion size and its spatial relationship to the bony cortex (intramedullary, subcortical, and transcortical) and results were correlated with those of planar technetium 99m bone scintigraphy. RESULTS: Findings on bone scans were negative for all intramedullary lesions without cortical involvement shown on MR imaging, regardless of their size. Findings on bone scans (71.3% for transcortical and 33.8% for subcortical) were frequently positive for lesions with cortical involvement (trans- or subcortical), and the probability of positive findings on bone scans was also influenced by the lesion size. Statistical analysis showed a positive correlation among cortical involvement, lesion size, and positive findings on bone scintigraphy (p < 0.0001). CONCLUSION: Location (the presence of cortical bone involvement on MR imaging) and size of the vertebral body metastases appear to be important contributing factors to the difference in detection rates between MR imaging and bone scintigraphy. Cortical involvement is likely the cause of positive findings on bone scans. Early vertebral metastases tend to be small and located in the medullary cavity without cortical involvement, and therefore, findings may be positive on MR images but negative on bone scans.

Pixel analysis of MR perfusion imaging in predicting radiation therapy outcome in cervical cancer.

The purpose of this study was to assess heterogeneity of tumor microcirculation determined by dynamic contrast-enhanced magnetic resonance (MR) imaging and its prognostic value for tumor radiosensitivity and long-term tumor control using pixel-by-pixel analysis of the dynamic contrast enhancement. Sixteen patients with advanced cervical cancer were examined with dynamic contrast-enhanced MR imaging at the time of radiation therapy. Pixel-by-pixel statistical analysis of the ratio of post- to precontrast relative signal intensity (RSI) values in the tumor region was performed to generate pixel RSI distributions of dynamic enhancement patterns. Histogram parameters were correlated with subsequent tumor control based on long-term cancer follow-up (median follow-up 4.6 years; range 3.8-5.2 years). The RSI distribution histograms showed a wide spectrum of heterogeneity in the dynamic enhancement pattern within the tumor. The quantity of low-enhancement regions (10th percentile RSI < 2.5) significantly predicted subsequent tumor recurrence (88% vs. 0%, P = 0.0004). Discriminant analysis based on both 10th percentile RSI and pixel number (reflective of tumor size) further improved the prediction rate (100% correct prediction of subsequent tumor control vs. recurrence). These preliminary results suggest that quantification of the extent of poor vascularity regions within the tumor may be useful in predicting long-term tumor control and treatment outcome in cervical cancer. J. Magn. Reson. Imaging 2000;12:1027-1033.

Proper ROC analysis and joint ROC analysis of the satisfaction of search effect in chest radiology.

RATIONALE AND OBJECTIVES: The purpose of this study was to test whether the satisfaction of search (SOS) effect in chest radiology could be demonstrated with proper receiver operating characteristic (ROC) curves and with joint detection and localization ROC curves. MATERIAL AND METHODS: Data from an earlier ROC study of SOS in chest radiology were analyzed with three proper ROC models and one ROC model for joint detection and localization. Fits of the models were compared on the basis of likelihood-ratio chi-squared statistics (G2). To examine further the validity of the SOS effect in chest radiology, the authors also replicated the earlier study with a new sample of readers, analyzing the new data with the same methods. RESULTS: The proper contaminated binormal model fit the data better than the other two proper ROC models. Contaminated binormal analysis of the earlier and the replication experiment demonstrated an SOS effect: a reduction in area under the ROC curve for detection of the native abnormalities with the addition of nodules. Similarly, joint ROC analysis producing curves that appropriately cross the chance line gave similar results. CONCLUSION: Preventing inappropriate chance line crossing reduces measurement error and provides more powerful statistical tests. Results of both experiments showed that the SOS effect in chest radiology can be demonstrated with ROC methods that avoid inappropriate crossing of the chance line.

Adjunctive non-pharmacological analgesia for invasive medical procedures: a randomised trial.

BACKGROUND: Non-pharmacological behavioural adjuncts have been suggested as efficient safe means in reducing discomfort and adverse effects during medical procedures. We tested this assumption for patients undergoing percutaneous vascular and renal procedures in a prospective, randomised, single-centre study. METHODS: 241 patients were randomised to receive intraoperatively standard care (n=79), structured attention (n=80), or self-hypnotic relaxation (n=82). All had access to patient-controlled intravenous analgesia with fentanyl and midazolam. Patients rated their pain and anxiety on 0-10 scales before, every 15 min during and after the procedures. FINDINGS: Pain increased linearly with procedure time in the standard group (slope 0.09 in pain score/15 min, p<0.0001), and the attention group (slope 0.04/15 min; p=0.0425), but remained flat in the hypnosis group. Anxiety decreased over time in all three groups with slopes of -0.04 (standard), -0.07 (attention), and -0.11 (hypnosis). Drug use in the standard group (1.9 units) was significantly higher than in the attention and hypnosis groups (0.8 and 0.9 units, respectively). One hypnosis patient became haemodynamically unstable compared with ten attention patients (p=0.0041), and 12 standard patients (p=0.0009). Procedure times were significantly shorter in the hypnosis group (61 min) than in the standard group (78 min, p=0.0016) with procedure duration of the attention group in between (67 min). INTERPRETATION: Structured attention and self-hypnotic relaxation proved beneficial during invasive medical procedures. Hypnosis had more pronounced effects on pain and anxiety reduction, and is superior, in that it also improves haemodynamic stability.

Anatomic distribution of metastases in the vertebral body and modes of hematogenous spread.

STUDY DESIGN: A retrospective review of the magnetic resonance spine examinations of 49 patients with metastatic bone disease to the spine was performed. OBJECTIVES: To determine whether the pattern of metastatic distribution in the spine correlates with the type of primary tumor and theoretical mode of hematogenous spread by arterial or venous routes. SUMMARY OF BACKGROUND DATA: In 1940, Batson theorized a venous plexus route by which tumors spread to the spine from pelvic tumors such as prostatic carcinoma. It this theory is true, the venous vascular anatomy of the spine would result in metastases being deposited in the central or posterior vertebral body, whereas arterial deposits would occur near the end-plates. METHODS: Each vertebral body was divided into 27 equal cells in the magnetic resonance images; the central and posterior cells in the midsagittal view were defined as central, and the other cells were defined as peripheral. The primary tumor was assigned to either the arterial or venous group based on Batson's proposed mode of spread. The average number of lesions per involved vertebral body in the central and peripheral regions was calculated. RESULTS: There was no statistically significant correlation between tumors with proposed arterial/venous routes of metastasis and central/peripheral location of metastatic deposits. CONCLUSION: The mechanism by which tumors spread to the vertebral body may not be via a pure arterial or venous route. Other mechanisms such as tissue specificity, cascade system, and closed loop circulation system may be involved.

Sonography of acute appendicitis in pregnancy.

BACKGROUND: Clinical evaluation of acute appendicitis is difficult in pregnant patients. Delay in diagnosis is associated with increased fetal mortality. The purpose of our study was to assess the value of sonography in the diagnosis of acute appendicitis in pregnant women. METHODS: We obtained sonograms in 22 pregnant women suspected of acute appendicitis. All sonograms were performed using graded-compression to detect an enlarged appendix. The sonographic criteria for acute appendicitis were detection of a noncompressible blindended and tubular multilayered structure of maximal diameter greater than 6 mm. RESULTS: The sonographic findings were correlated with surgical findings in seven cases and clinical follow-up in 15 cases. Acute appendicitis was diagnosed by sonography in three of 22 patients, and in all but one was confirmed by surgical and pathologic findings. In the remaining 19 patients, 15 improved on clinical followup; three were shown to have a normal appendix at surgery and one had focal acute inflammation at the tip of the appendix. CONCLUSIONS: Our experience suggests that graded-compression sonography is a useful procedure in pregnant patients suspected of acute appendicitis and has a similar accuracy as in nonpregnant women, especially in the first and second trimester.

Does a normal small-bowel enteroclysis exclude small-bowel disease? A long-term follow-up of consecutive normal studies.

The purpose of our study was to determine if a normal small-bowel enteroclysis excludes small-bowel disease in adult patients, using long-term follow-up as the major reference standard. We reviewed 193 consecutive small-bowel enteroclysis (SBE) studies completed during a period from January 1987 to February 1989, of which 83 were judged to be normal at the time of the study. Eight of these latter patients were excluded due to inadequate follow-up. The indications included detection of gastrointestinal bleeding, small-bowel obstruction, Crohn's disease, nonspecific abdominal pain, chronic diarrhea, and a miscellaneous group. Each patient was followed for at least 3 years by chart review or until a definite diagnosis was established. Six of the 75 patients whose SBE was originally interpreted as normal were eventually judged to have small-bowel disease. The remaining 69 patients were judged to be free of small-bowel disease by autopsy, surgical laparotomy, endoscopic observation or biopsy, or long-term follow-up for at least 3 years. Therefore, a normal SBE correctly excluded small-bowel disease in 69 of our 75 patients (true negatives) and failed to diagnose disease in six patients (false negatives), for a specificity of .92 +/- .03 (SE). In this experience, SBE was sufficiently specific in most patients to exclude small-bowel disease.

Comparison of oral cholecystography and ultrasonography for evaluating chronic cholecystitis using patient outcome as the reference standard.

RATIONALE AND OBJECTIVES: The authors compared oral cholecystography (OCG) with ultrasound (US) in the detection of chronic gallbladder disease using clinical outcome, rather than pathology results, as the reference standard. METHODS: The authors interviewed 269 patients who underwent either OCG, US, or both, for evaluation of chronic right upper quadrant abdominal pain. The authors considered patients who underwent cholecystectomy with improved symptoms 1 to 4 years after surgery to be reference-standard positive for gallbladder disease, and patients with objective evidence of an alternative diagnosis (eg, peptic ulcer disease), which improved with therapy as reference-standard negative. RESULTS: The sensitivity and specificity of OCG were 83% and 97%, respectively, and for US, 86% and 90%, respectively. CONCLUSIONS: OCG is comparable with US in evaluating of chronic gallbladder disease. In institutions where OCG is used for diagnosing chronic cholecystitis, it may be reasonable to continue using OCG.

The influence of clinical history on visual search with single and multiple abnormalities.

RATIONALE AND OBJECTIVES: Facilitation of detection by clinical history generally has been found with a single abnormality per image but not with multiple abnormalities. Multiple abnormalities per image can occasion a "satisfaction-of-search" effect in which detection of one lesion is reduced in the presence of other distant lesions. Our experiment studied the combined effect of multiple abnormalities and clinical history on accuracy. METHODS: Detection of native lesions was measured 1) with histories suggestive of the native abnormality; 2) with these histories and added simulated pulmonary nodules; and 3) with the same added nodules and histories suggestive of metastatic disease. These conditions also were compared with those of a previous experiment that were similar but included no history. RESULTS: Detection was substantially improved for appropriately prompted abnormalities even in the presence of a pulmonary nodule. In fact, satisfaction of search was not found in the presence of an appropriate history. Detection of unprompted abnormalities was unchanged when prompts indicated other abnormalities actually present. Prompted abnormalities were detected earlier in search. CONCLUSIONS: History appears to direct perceptual resources to the prompted abnormalities, thereby alleviating satisfaction of search. The presence of nodules yielded a small but consistent reduction in total search time for searches involving false responses, suggesting that satisfaction of search may depend more on reduction in search time than had been indicated by previous research.

Gadolinium-enhanced MRI of soft tissue masses.

The efficacy of gadopentetate dimeglumine (Gd-DTPA) enhanced magnetic resonance (MR) imaging in the diagnosis and differentiation of soft-tissue, neoplastic and non-neoplastic lesion has not been well established. Thirty patients with soft tissue masses (18 neoplastic and 12 non-neoplastic) were studied, using MR imaging with and without administration of Gd-DTPA. Gd-DTPA proved helpful in characterisation of several entities, including differentiation of solid mass from proteinaceous cyst, demonstration of tumour nodules within haemorrhagic or necrotic masses, and delineation of tumour adjacent to oedema. The use of Gd-DTPA may provide additional information for tissue specificity and, in complicated cases, Gd-DTPA may also provide essential information that cannot be obtained using other methods. We recommend the use of contrast enhanced MR as an adjunct to conventional MR imaging in the initial assessment of musculoskeletal soft tissue masses. However, T2-weighted images show better tissue contrast of the lesions, and are equal to contrast enhanced images in delineation of tumour margins. Non-contrast enhanced images are, therefore, probably adequate for the delineation of lesions for surgical planning when a diagnosis has already been made.

Three-dimensional viewing of and dosimetric calculations in Au-198 implants of the prostate.

A three-dimensional system for dosimetric calculation of radiation from interstitial brachytherapeutic implants was developed and was compared with conventional dosimetry performed with a commercial two-dimensional system. Software programs written for this study enabled the authors to place radioactive sources in the correct reconstructed anatomic locations, compute the isodose distribution around these sources, and display the isodose curves in their correct relationship to anatomic structures. Eight radiation oncologists evaluated the usefulness of both systems. Verification studies in phantoms and in 20 patients with gold-198 implants in the prostate gland showed that the experimental system was very accurate in volume reconstruction, seed localization, isodose distribution, point-dose calculation, and computation of dose-volume histograms. Although the dose depictions in the two systems matched almost exactly, statistically significant differences existed in interpretation of the dosimetric data generated by both systems. For example, the oncologists consistently believed that the dose to the prostate was lower when the three-dimensional system was used (P less than or equal to .0001).

CT analysis of metastatic neoplasms of the kidney. Comparison with primary renal cell carcinoma.

The CT findings in 32 patients with pathologically proven metastases to the kidney were compared to findings in 74 patients with renal cell carcinoma. Fourteen CT criteria were chosen to describe and characterize the lesions and 2 radiologists evaluated the CT images retrospectively according to these criteria. Renal metastases were characterized as small, multiple, bilateral, wedge-shaped, less exophytic, and located within the renal capsule. Renal cell carcinomas were single, unilateral, nonwedge-shaped, and exophytic, and easily transgressed the renal capsule. The sensitivity of CT to discriminate renal cell carcinoma from renal metastasis was 93.2% for renal cell carcinoma, and to discriminate renal metastasis from renal cell carcinoma was 75.0% for renal metastases by computer posterior probabilities. This study indicates that CT is useful for distinguishing these clinically important tumors. By using posterior probability, some unnecessary biopsies may be avoided.

Magnetic resonance imaging and computed tomography in pediatric head and neck masses.

Fifty-three magnetic resonance imaging (MRI) and 25 computed tomography (CT) studies of 53 head and neck masses in pediatric patients were reviewed retrospectively. All lesions had pathologic proof except for 2 metastatic and 2 recurrent lesions, which only had prior pathologic confirmation at their primary sites. These included 12 malignant tumors, 23 benign tumors, 6 inflammatory masses, and 12 congenital lesions. The MRI performance ranged predominantly from good to excellent in detection of the lesion and the extent of involvement and in contrast to the surrounding tissue; when CT comparison was available, MRI proved to be equal to or better than it in detection of these factors and in preoperative diagnosis. Our results suggest that MRI should be the method of choice for the initial evaluation of the pediatric head and neck region, especially in those patients requiring multiple examinations. However, CT and MRI should be used conjunctively in complicated cases, especially those possibly involving lesions with calcifications or bony involvement.

Plaque modification with tetracycline: enhanced tissue ablation with the excimer laser.

Tetracycline has been shown to collect selectively in atherosclerotic plaque and is a known photosensitizing agent. To determine if tetracycline enhances the photoablative effects of the ultraviolet xenon-fluorine excimer laser, the authors exposed four cadaveric aortic samples to tetracycline and four to only normal saline. Ninety-three sites in the samples were subjected to laser energy and analyzed with light microscopy for crater depth and width and for degree of thermal injury. Forty-three of the sites were histologically normal, and 50 were atherosclerotic. Crater depth did not differ significantly in atherosclerotic and normal sites not exposed to tetracycline. Atherosclerotic sites exposed to tetracycline showed significantly deeper craters compared with those in normal, exposed sites. The effects of tetracycline exposure and histologic characteristics (normal vs atherosclerotic) on crater width and thermal injury were independent and additive. When the excimer laser is used for treatment, tetracycline can definitely enhance atherosclerotic plaque ablation.

Influence of clinical history upon detection of nodules and other lesions.

The authors reexamined a suspected difference in the effects of clinical information upon detection of nodules vs. more diverse lesions by directly incorporating classification specificity into detection ROC analysis. Categorical prompts, correct for specific abnormalities, led to detection superior to unprompted reading when non-nodule trials (various lesion types) were analyzed. Trials that contained pulmonary nodules, or contained no lesions but had been preceded by "possible tuberculosis" or "rule out metastatic disease" prompts, failed to demonstrate the diagnostic prompt superiority. Perceptual responses may differ when nodules are compared with more complex lesions.