Diagnostic accuracy of mammography readers and their memory performance have no correlation with each other.

INTRODUCTION: The study aims to determine if any association exists between visual memory performance and diagnostic accuracy performance in a group of radiologist mammogram readers. MATERIALS AND METHODS: One hundred proven mammograms (23 with cancers) were grouped into 5 sets of 20 cases, with sets being of equal difficulty. Pairs of sets were presented in 5 reads (40 cases per read, order random) to a panel of 8 radiologist readers (either present or past screening readers, with experience range from <1 year to >20 years). The readers were asked to either 'clear' or 'call back' cases depending on need for further workup, and at post-baseline reads to indicate whether each case was 'new' or 'old' (i.e. remembered from prior read). Two sets were presented only at baseline (40 cases per reader), and were used to calculate the reader's false recollection rate. Three sets were repeated post-baseline once or twice (100 cases per reader). Reading conditions were standardised. RESULTS: Memory performance differed markedly between readers. The number of correctly remembered cases (of 100 'old' cases) had a median of 10.5 and range of 0-58. The observed number of false recollections (of 40 'totally new' cases) had a median of 2 and range of 0-17. Diagnostic performance measures were mean (range): sensitivity 0.68 (0.54-0.81); specificity 0.82 (0.74-0.91); positive predictive value (PPV) 0.55 (0.50-0.65); negative predictive value (NPV) 0.89 (0.86-0.93) and accuracy 0.78 (0.76-0.83). Confidence intervals (CIs; 95%) for each reader overlapped for all the diagnostic parameters, indicating a lack of statistically significant difference between the readers at the 5% level. The most sensitive and the most specific reader showed a trend away from each other on sensitivity, specificity, NPV and PPV; their accuracies were 0.76 and 0.82, respectively, and their accuracy 95% CIs overlapped considerably. Correlation analysis by reader showed no association between observed memory performance and any of the diagnostic accuracy measures in our group of readers. In particular, there was no correlation between diagnostic accuracy and memory performance. CONCLUSION: There was no association between visual memory performance and diagnostic accuracy as a screening mammographer in our group of eight representative readers. Whether a radiologist has a good or a bad visual memory for cases, and in particular mammograms, should not impact on his or her performance as a radiologist and mammogram reader.

The promising role of 18F-FDG PET in detecting infected lower limb prosthesis implants.

UNLABELLED: The purpose of this study was to evaluate the feasibility of using 18F-FDG and PET for the detection of infection associated with lower limb arthroplasty. METHODS: Seventy-four prostheses in 62 patients in whom infection was suspected after artificial hip or knee placement were studied with this technique. Images were obtained 60 min after an intravenous injection of FDG. The images were interpreted as positive for infection if tracer uptake was increased at the bone-prosthesis interface. A final diagnosis was made by surgical exploration or clinical follow-up for 1 y. PET results were compared with the follow-up outcome in all patients. RESULTS: The sensitivity, specificity, and accuracy of PET for detecting infection associated with knee prostheses were 90.9%, 72.0%, and 77.8%, respectively. The sensitivity, specificity, and accuracy of PET for detecting infection associated with hip prostheses were 90%, 89.3%, and 89.5%, respectively. Overall, the sensitivity was 90.5% and the specificity was 81.1% for detection of lower limb infections. CONCLUSION: FDG PET is a useful imaging modality for detecting infections associated with lower limb arthroplasty and is more accurate for detecting infections associated with hip prostheses than for detecting infections associated with knee prostheses.

Exclusion of chronic osteomyelitis with F-18 fluorodeoxyglucose positron emission tomographic imaging.

PURPOSE: Excluding the diagnosis of chronic osteomyelitis is often difficult with noninvasive techniques, especially when bone anatomy and structure have been altered by trauma, surgery, or soft-tissue infection. It has been reported that fluorodeoxyglucose (FDG) positron emission tomography (PET) has excellent potential to diagnose osteomyelitis. In this study, the accuracy of FDG PET in the diagnosis of chronic osteomyelitis was determined. METHOD: Twenty-two patients with possible osteomyelitis (5 in the tibia, 5 in the spine, 4 in the proximal femur, 4 in the pelvis, 2 in the maxilla, and 2 in the feet) who underwent FDG PET imaging and on whom operative or clinical follow-up data were available were included in this analysis. The final diagnosis was made by surgical exploration or clinical follow-up during a 1-year period. RESULTS: FDG PET correctly diagnosed the presence or absence of chronic osteomyelitis in 20 of 22 patients. Six had chronic osteomyelitis and 16 proved to be free of osteomyelitis. FDG PET correctly identified all six patients with chronic osteomyelitis but produced two false-positive results. This study had a sensitivity rate of 100%, a specificity rate of 87.5%, and an accuracy rate of 90.9%. CONCLUSION: FDG PET is a highly effective imaging method to exclude osteomyelitis when a negative scan result is obtained. However, positive results can be caused not only by true osteomyelitis but also by inflammation in the bone or surrounding soft tissues as a result of other causes. Overall, FDG PET may prove to be the preferred study in the management of patients with possible chronic osteomyelitis.

Diagnostic accuracy of salivary scintigraphic indices in xerostomic populations.

PURPOSE: Three decades of work to enhance the diagnostic accuracy of salivary scintigraphy have generated various plausible decision criteria. This study evaluates four commonly cited numeric indices in studies of xerostomic populations and how accurately they identify Sjögren's syndrome, chronic sialadenitis, radiation sialadenitis, and drug effects and distinguish each from the other. METHODS: Stimulated dynamic salivary scintigraphy was performed on 295 xerostomic patients and on 31 controls. The nonparametric area under the receiver operating characteristic curves expressed the diagnostic accuracy of the following scintigraphic indices: the parotid:submandibular ratio of unstimulated glandular activity, the peak:baseline uptake ratio, its time of occurrence, and the stimulated excretion fraction. RESULTS: The stimulated excretion fraction distinguished Sjögren's syndrome and radiation sialadenitis from healthy states with respective accuracies of 0.78 and 0.90. The maximum diagnostic payoff in Sjögren's syndrome occurred at a cutoff of 73%, yielding a 73% rate of test sensitivity and a 73% rate of specificity. The other three indices were not useful. Even the stimulated excretion fraction performed indifferently or poorly in most other diagnostic tasks. CONCLUSIONS: In the scintigraphic examination of xerostomic and healthy populations, an acceptable diagnostic utility of the stimulated excretion fraction was evident only in Sjögren's syndrome and radiation sialadenitis. When presented with differential diagnostic alternatives not involving radiation sialadenitis, none of the four numeric indices performed acceptably.

Variability of quantitative scintigraphic salivary indices in normal subjects.

UNLABELLED: Several quantitative measures of salivary uptake and discharge have been proposed recently in the scintigraphic evaluation of xerostomia. We investigated the scatter of four time-activity curve C(TAC)-derived indices in a group of volunteer subjects who met extensive inclusionary and exclusionary criteria of salivary normalcy. METHODS: Thirty-one adult volunteers underwent dynamic salivary scintigraphy with gustatory stimulation. Any candidates with subjective xerostomia, conditions or medications associated with dry mouth, salivary gland enlargement or pregnancy were excluded from study. All subjects had normal oral exams, xerostomia scores and unstimulated whole-mouth salivary flow rates. After the intravenous administration of 99mTcO-4, scintigraphy was performed with generation of TACs derived from regions of interest centered about the four major salivary glands and the oral cavity. At 45 min postinjection, hard lemon candy was given for 15 min as a gustatory stimulus. The following functional indices were calculated for each gland: partitioned percentage (PP) of total prestimulated activity, maximum net uptake ratio (NUR) and its time of occurrence (TNUR) and percentage stimulated discharge fraction (DF). RESULTS: The following ranges were observed: parotid PP, 22%-49%; submandibular PP, 4%-31%; parotid NUR, 2.2-16.0; submandibular NUR, 1.4-16.2; parotid TNUR, 8-45 min; submandibular TNUR, 2-45 min; parotid DF, 20%-99%; and submandibular DF, 27%-98%. Every subject except one 91-yr-old man showed frequent periodic unstimulated oral transfer of salivary activity with a rising oral TAC and responded to gustatory stimulation. CONCLUSION: So-called quantitative indices may perform poorly in the scintigraphic evaluation of xerostomic patients because the effects of normal simultaneous glandular trapping, uptake, oral discharge and possible vascular washout combine to widen reference limits. Coordinated analysis of oral cavity and glandular activities, glandular index averaging and better temporal resolution may help improve diagnostic performance.