Increased brain apparent diffusion coefficient in children with neurofibromatosis type 1

PURPOSE

To describe the changes in brain water diffusibility in five anatomic locations in children with neurofibromatosis type 1 (NF 1) compared with these changes in control subjects and to describe the water diffusibility changes associated with hyperintense basal ganglia lesions in children with NF 1.

MATERIALS AND METHODS

Twenty highly related pairs of children consisting of one child with NF 1 and one unaffected child were examined. Prospective comparisons of isotropic apparent diffusion coefficient (ADC) values at five anatomic locations were performed, with and without T2-hyperintense lesions included. Retrospective analysis of hyperintense globus pallidus lesions in 16 children and in the paired control subjects also was performed.

RESULTS

Significant increases in ADC values were seen in all five anatomic locations in the NF 1 group. The greatest increases were seen in the globus pallidus (14%; P =.002) and brachium pontis (10.8%; P =.003). With exclusion of hyperintense lesions, significant ADC increases were measured in four locations. Significant ADC increases were seen in hyperintense globus pallidus lesions in the NF 1 group compared with ADC values in the normal-appearing contralateral globus pallidus (4.9%; P =.02) and those in the globus pallidus of the paired control subjects (16%; P =.003).

CONCLUSION

Significant ADC increases were measured both in the hyperintense lesions and in the normal-appearing areas of the brain in children with NF 1.

Comparison of patient age with MR imaging features of gangliogliomas

OBJECTIVE

The purpose of this study was to compare MR imaging features of gangliogliomas in children less than 10 years old with those seen in patients at least 10 years old.

MATERIALS AND METHODS

Our study population consisted of 15 female patients and 10 male patients with a mean age of 20 years. The early childhood group was composed of six children with a mean age of 5.5 years. The older group was composed of 19 patients with a mean age of 25.6 years. We assessed tumor volume, tumor location, percentage of tumor that was cystic, pattern of contrast enhancement, and degree of edema.

RESULTS

The temporal lobe was the most common tumor location in both groups. Mean tumor volume in the early childhood group was 83 cm3, which was significantly larger than the mean tumor volume (9.78 cm3) for the older group (p = 0.001). Cystic tumors were more common in the early childhood group (83%) than in the older group (63%), and the average percentage of cysts in the cystic tumors was much higher in the early childhood group (67%) than in the older group (30%). Contrast enhancement was seen in five of six early childhood tumors and 13 of 16 tumors in older patients. Four of six tumors in the early childhood group and five of 19 tumors in the older patient group had associated edema.

CONCLUSION

The mean tumor volume of gangliogliomas in the early childhood group was significantly larger than that of the older patient group. This finding may be indicative of differences in tumor growth patterns in the two groups, ability of the hemicranium to adjust to mass effect in childhood, or sampling error as a result of a relatively small sample size.

Mammography Pain in Women Treated Conservatively for Breast Cancer

In this study, pain during mammography in women treated conservatively for breast cancer was examined. It studied pain intensity and its relation to a variety of demographic, medical, and pain coping variables as well as to objective measures of breast compression. Ninety-nine women, treated with lumpectomy (with or without radiation) and undergoing follow-up screening mammography, were asked about strategies they use to cope with everyday pain and then were asked to report pain experienced during the mammogram. Treated and untreated breasts were rated separately and compared with a sample of 125 control women with no history of breast cancer. Women reported significantly greater pain in the treated breast (41% greater than the untreated breast and 32% greater than the control group). There was no consistent relationship between mammography pain and pain coping. Average intensity of pain at last mammogram was the best predictor of pain in both breasts. Women treated conservatively for breast cancer experience significantly greater pain during mammography of their treated breast. Radiologists and technologists can identify women at risk for a painful mammogram by asking about the pain at last mammogram. By applying pain-reducing interventions, they might be able to make the mammography experience more tolerable for these women.

Correlation between findings on chest radiography and survival in neonates with congenital diaphragmatic hernia

OBJECTIVE

Predictors of survival are helpful when deciding on aggressiveness of care of neonates with congenital diaphragmatic hernia and respiratory failure. We evaluated findings on chest radiography as potential predictors of survival in these patients.

MATERIALS AND METHODS

Findings on chest radiographs of neonates less than 24 hr old with congenital diaphragmatic hernia were evaluated. Radiographic findings analyzed included percentage of aerated ipsilateral lung, percentage of aerated contralateral lung, mediastinal shift, and hernia contents. Each finding was compared with survival (equated with hospital discharge) using a Mantel-Haenszel chi-square test. Survival was also determined using the total number of poor prognostic findings present in any one patient.

RESULTS

In the 73 neonates with congenital diaphragmatic hernia in our study, the overall survival rate was 55%. There were statistically significant relationships between survival rate and percentage of ipsilateral aeration (p = 0.001), percentage of contralateral aeration (p = 0.016), and mediastinal shift (p = 0.026). The survival rate for multiple poor prognostic factors was 0% with four of four factors and 20% with three of four factors (p = 0.001). Survival rate was not influenced by prematurity (p = 0.102), sex (p = 0.104), or side of hernia (p = 0.895).

CONCLUSION

Findings on initial chest radiography are helpful in predicting survival in neonates with congenital diaphragmatic hernia.

Bronchial anastomotic complications in lung transplant recipients: virtual bronchoscopy for noninvasive assessment

PURPOSE

To compare the accuracy of virtual bronchoscopy (VB) with that of axial computed tomography (CT) in the assessment of bronchial anastomotic complications in lung transplant recipients.

MATERIALS AND METHODS

Twenty-seven bronchial anastomoses in 17 patients were evaluated with helical CT. Axial CT and VB images were evaluated for surface irregularity and the presence, length, and severity of stenosis. Findings were correlated with the results of fiberoptic bronchoscopy (FOB).

RESULTS

There were 12 anastomotic stenoses at FOB. Pooled accuracy (among all four readers) of VB and axial CT for diagnosis of clinically relevant stenosis was 97% and 80%, respectively, at the right bronchial anastomoses and 92% and 75%, respectively, at the left bronchial anastomoses. Pooled accuracy of VB and Axial CT for stenosis length was 72% and 62%, respectively, at the right anastomoses and 81% and 69%, respectively, at the left anastomoses. These differences were not statistically significant. Both the VB and axial CT images showed surface irregularities when anastomotic infection (n = 2) or dehiscence (n = 1) was present but resulted in an overdiagnosis of mucosal abnormalities when anastomoses were normal.

CONCLUSION

VB was slightly more accurate than axial CT for diagnosis of clinically relevant stenoses at bronchial anastomoses in lung transplant recipients. However, because VB is not 100% accurate and has no role in the diagnosis of infection or dehiscence, it probably will not replace FOB for assessment of bronchial anastomotic complications in this population.

Interobserver variability in the interpretation of unenhanced helical CT for the diagnosis of ureteral stone disease

PURPOSE

The purpose of this study was to analyze interobserver agreement in the interpretation of unenhanced helical CT (UHCT) for the evaluation of ureteral stone disease and obstruction.

METHOD

One hundred three UHCT examinations were independently and retrospectively reviewed by five readers including attending radiologists, a radiology resident, and an attending urologist. Examinations were interpreted as positive, negative, or indeterminate for ureteral stone disease and obstruction. The Cohen kappa test was used to measure interobserver agreement. The accuracy of the readers was also assessed.

RESULTS

The kappa value ranged from 0.67 to 0.71 among the three attending radiologists and from 0.65 to 0.67 among the radiology attending physicians and radiology resident. Although the urologist tended to agree less well with the other readers (kappa range: 0.33-0.46), there was no statistically significant difference (p < 0.05) in the accuracy among all five readers. The percentage of cases interpreted as indeterminate ranged from 8 to 25% and almost invariably involved difficulty distinguishing phleboliths from minimally obstructing distal ureteral calculi. The percentage of UHCT scans correctly interpreted as positive and correctly interpreted as negative ranged from 73% (n = 27) to 86% (n = 32) and 63% (n = 22) to 86% (n = 30), respectively.

CONCLUSION

Interobserver agreement was very good among the radiology attending physicians and resident and moderate with the urologist. The examination is an accurate technique in the evaluation of ureteral stone disease, although limitations exist, particularly in the diagnosis of minimally obstructing distal ureteral calculi.

Contrast-enhanced CT of intrahepatic and hilar cholangiocarcinoma: delay time for optimal imaging

OBJECTIVE

The purpose of this study was to determine the optimal time for obtaining delayed images with contrast-enhanced CT in patients who have intrahepatic or hilar cholangiocarcinoma.

SUBJECTS AND METHODS

CT studies were performed in 25 consecutive patients with proven cholangiocarcinoma, including six patients who had undergone radiotherapy or chemotherapy. Dynamic images of the liver were obtained after 150 ml of IV contrast material was administered at 3 ml/sec. Delayed CT images were then obtained at 10, 20, and 30 min. Tumor-liver attenuation difference was determined quantitatively for each time period. Images were qualitatively evaluated by three observers for attenuation of the tumor (hypoattenuating, isoattenuating, or hyperattenuating) relative to the liver. Observer confidence for tumor detection was graded on a four-point scale. Dynamic and delayed images were compared for tumor conspicuity.

RESULTS

On dynamic images, 18 tumors (72%) were hypoattenuating, six (24%) were isoattenuating, and one was heterogeneous. On delayed images, 15 (60%) of these 25 tumors were isoattenuating and nine (36%) were hyperattenuating compared with the liver. Tumor-liver attenuation difference was greatest on dynamic studies (p < .01) and did not differ significantly among the three delay times (p > .20). All tumors seen on delayed images were also seen on dynamic images; however, in three patients (12%), the confidence level for presence of tumor was better on delayed than on dynamic images. Confidence levels for presence of tumor did not vary significantly among the three delay times. Attenuation values on dynamic and delayed images did not differ for the groups of patients who had or had not undergone prior radiotherapy or chemotherapy (p > .05).

CONCLUSION

In the evaluation of hilar or intrahepatic cholangiocarcinoma, delayed CT images are helpful for tumor characterization and may improve observer confidence for the presence of tumor. The optimal time for acquisition of delayed images is 10-20 min after contrast media injection.

Zebra pattern: a diagnostically challenging hepatic parenchymal enhancement pattern at CT arterial portography

PURPOSE

To investigate the effect of arterial injection site and splenic volume on the hepatic zebra pattern seen at computed tomographic (CT) arterial portography.

MATERIALS AND METHODS

Images from CT arterial portographic examinations, performed via either the splenic artery (SA)(n = 47) or superior mesenteric artery (SMA)(n = 51) in 98 patients, were reviewed. The hepatic parenchymal enhancement pattern was assessed by three blinded reviewers. Splenic volume was determined.

RESULTS

Twenty-two of 98 (22%) CT arterial portographic studies showed a zebra pattern: 10 of 47 (21%) with injection via the SA and 12 of 51 (24%) with injection via the SMA. The mean percentage of hepatic parenchyma with nontumorous perfusion defects was 55% with the zebra pattern versus 12% without (P < .001). For SA injections, the mean splenic volume was lower in patients with the zebra patterns (321 vs 409 cm3, P = .09). For SMA injections, it was higher in patients with zebra patterns (372 vs 291 cm3, P = .10).

CONCLUSION

The zebra pattern can cause difficulties in interpreting images. It is due to alternating, well-defined regions of portal venous hyper- and hypoperfusion; it likely has a multifactorial cause and is likely due to technical parameters such as the injection site, the volume of the spleen, and the hemodynamic effects of the tumor.

Pulmonary abnormalities and PET data analysis: a retrospective study

PURPOSE

To assess methods of standard uptake ratio (SUR) calculation with 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) positron emission tomography (PET) in indeterminate focal pulmonary abnormalities.

MATERIALS AND METHODS

One hundred ninety-seven adult patients with indeterminate pulmonary abnormalities had complete FDG PET data, consistent methods of data acquisition, and definitive diagnosis with tissue biopsy or negative 2-year follow-up findings. PET studies were evaluated by using SURs calculated with the average or maximum region-of-interest pixel value in the numerator and with weight, lean body mass, or body surface area in the denominator.

RESULTS

One hundred twenty malignant lesions and 77 benign processes were identified. Receiver operating characteristic (ROC) curve areas were statistically significantly larger with the average rather than the maximum pixel value in the calculation of the SUR for any of the three denominators (P < or = .05). SURs calculated with weight versus lean body mass versus body surface area in the denominator showed no statistically significant difference in ROC curve areas.

CONCLUSION

SURs determined by using average pixel values provide statistically significant improvement in ROC curve areas over those determined by using maximum pixel values. Weight, lean body mass, and body surface area in the denominator of the SUR calculation provide equivalent ROC curve areas and are therefore equivalent in accuracy in this population.

Estimation of myocardial blood flow for longitudinal studies with 13N-labeled ammonia and positron emission tomography

BACKGROUND

Although several modeling strategies have been developed and validated for quantification of myocardial blood flow (MBF) from 13N-labeled ammonia positron emission tomographic data, a comparison of noise characteristics of the various techniques in serial studies is lacking.

METHODS AND RESULTS

Dynamic 13N-labeled ammonia positron emission tomographic imaging was performed at baseline and after pharmacologic stress in (1) single studies of four dogs with concomitant measurement of microsphere blood flow and (2) initial and follow-up studies of eight normal volunteers. Data were obtained from short-axis images for the blood pool and myocardial regions corresponding to the three arterial vascular territories. Indexes of MBF were obtained by four distinct techniques: (1) University of California, Los Angeles, two-compartment model, (2) Michigan two-compartment model, and (3) a one-compartment model with variable blood volume term. Coronary flow reserve (CFR) was measured as the ratio of stress/rest MBF. The estimated standard deviation of the measurement error for the relative change between studies of rest and stress MBF and CFR was determined for each technique. Estimates of MBF from all techniques showed good correlation with microsphere blood flow (r = 0.95 to 0.96) in canine myocardium. In human studies, similar mean estimates of MBF were found with all techniques. Techniques 1 and 3 showed the smallest interstudy variability in MBF and CFR. The estimated standard deviations for these techniques were approximately 20%, 30%, and 27% for rest MBF, stress MBF, and CFR, respectively.

CONCLUSION

Noninvasive quantification of MBF and CFR from dynamic 13N-labeled ammonia positron emission tomography is most reproducible with technique 1 or 3. The ability to account for differences in myocardial partial volume gives preference to technique 3. However, substantial interstudy variability in regional MBF remains, suggesting the importance of procedural factors or real temporal fluctuations in MBF.

Hepatic artery: variability in measurement of resistive index and systolic acceleration time in healthy volunteers

PURPOSE

To determine the intrinsic sampling variability of measurements of hepatic artery resistive index and systolic acceleration time in healthy subjects and to estimate the components of variability attributable to the sonographer, individual measurement, and subject.

MATERIALS AND METHODS

In a randomized, controlled (blinded) fashion, nine sonographers measured hepatic artery resistive index and systolic acceleration time in five healthy subjects by using Doppler ultrasound (US). Analysis of variance was used to estimate the contribution of several factors to the observed variability in measurements.

RESULTS

The standard deviation for a single measurement was 0.08 for resistive index and 39 msec for systolic acceleration time. For resistive index, the estimated variance components were 0.0012 (18%), 0.0004 (6%), and 0.0050 (76%) for the subject, sonographer, and intrinsic variability, respectively. For systolic acceleration time, the estimated variance components were 59 msec (4%), 264 msec (17%), and 1,250 msec (79%) for the subject, sonographer, and intrinsic variability, respectively.

CONCLUSION

Because of substantial variability in hepatic arterial measures, caution is indicated when interpreting small changes in the measurement of these Doppler US indexes.

Use of time during body computed tomography scanning in a tertiary care teaching hospital: focus on patient throughput

RATIONALE AND OBJECTIVES

To control costs, it is increasingly important to make efficient use of imaging technology. We sought to determine and analyze the time required to complete each step of a body computed tomography (CT) scan, focusing on factors that influence patient throughput.

METHODS

Over 4 weeks, we prospectively monitored the time required for each step of a body CT scan (i.e., image time, check time, and clear time). Covariate data were collected by patient status: outpatient, inpatient, emergency department (ED), and intensive care unit (ICU); work shift; and radiologist training level (junior resident, senior resident, fellow, and attending). Technologists also predicted whether repeat images would be requested by the radiologist.

RESULTS

Three hundred eighty CT examinations were studied: 277 for outpatients, 90 for inpatients, 9 for ED patients, and 4 for ICU patients. The mean total examination time was 44.7 min (mean image time = 33.1 min, mean review time = 8.2 min, and mean clear time = 3.4 min), which did not differ significantly with patient status. A second opinion was sought from a consultant radiologist on the scans of 44 patients. Consultation was requested significantly more frequently (1) by junior residents than by senior residents or fellows and (2) for ED and ICU patients (22% and 50%, respectively) than in outpatients and inpatients (10% and 14%, respectively). Repeat images were obtained from 75 patients, and this was not significantly related to patient status, scan type, or radiologist training level. When the technologist predicted that no repeat images were needed, this prediction agreed with the radiologist in 86% of the cases. When the technologist predicted that repeat images were necessary, this prediction agreed with the radiologist in 56% of the cases.

CONCLUSION

Reviewing scans before the patient leaves the CT suite adds considerably to the total time required to complete a scan, particularly if junior residents review scans. If technologists obtain repeat images at their discretion, time would be saved.

Selenium-based digital radiography of the chest: radiologists' preference compared with film-screen radiographs

OBJECTIVE

A new digital thoracic radiography system (Thoravision; Philips Medical Systems, Hamburg, Germany), which uses selenium as a detector material, was evaluated for observer preference. The system has been shown to have higher detection efficiency than conventional film-screen systems and thus could provide an image with reduced noise. The hypothesis tested in this study was that the selenium-based digital system would provide an image appearance for conventional thoracic imaging that would be equal or superior to that provided by a conventional film-screen system.

MATERIALS AND METHODS

Fifty-three patient volunteers were imaged at 120 kV with both the selenium-based system and a thoracic film-screen combination system (InSight HC; Kodak, Rochester, NY). Posteroanterior and lateral images were acquired with both systems, for a total of 212 images. Both imaging systems included a stationary 12:1 antiscatter grid. Exposures were the same for both imaging systems, and the digital images were printed to film. Images for the same patient were compared by six observers--three specialized chest radiologists and three general radiologists. Images included both normal chest radiographs and radiographs with abnormal findings. Each pair of images was ranked on a scale from 1 to 5 for preference of technique, with a score of 3 indicating no preference. Eleven anatomic features were evaluated in the posteroanterior views, and six features were evaluated in the lateral views. Statistical significance of preference was evaluated with Student's t test.

RESULTS

The chest radiologists had a statistically significant preference for the selenium-based system for all 17 features (p < .001). The general radiologists had a statistically significant preference for the selenium-based system for visualization of 10 of the 17 features (p < .05). Neither group had a statistically significant preference for the conventional images in any category.

CONCLUSION

The selenium-based system provided an image appearance that was significantly preferred by all radiologists, more strongly by those specializing in chest radiography. This study demonstrates that a digital thoracic imaging system can routinely produce images that are perceived as equal or superior to conventional images.