Estimating glomerular filtration rate in patients with acute kidney injury: a prospective multicenter study of diagnostic accuracy.

BACKGROUND: Estimating glomerular filtration rate (GFR) in acute kidney injury (AKI) is challenging, with limited data comparing estimated and gold standard methods to assess GFR. The objective of our study was to assess the performance of the kinetic estimated GFR (KeGFR) and Jelliffe equations to estimate GFR in AKI, using a radioisotopic method (technetium-diethylenetriaminepentaacetic acid) as a reference measure. METHODS: We conducted a prospective multicenter observational study in hospitalized patients with AKI. We computed the Jelliffe and KeGFR equations to estimate GFR and compared these estimations to measured GFR (mGFR) by a radioisotopic method. The performances were assessed by correlation, Bland-Altman plots and smoothed and linear regressions. We conducted stratified analyses by age and chronic kidney disease (CKD). RESULTS: The study included 119 patients with AKI, mostly from the intensive care unit (63%) and with Stage 1 AKI (71%). The eGFR obtained from the Jelliffe and KeGFR equations showed a good correlation with mGFR (r = 0.73 and 0.68, respectively). The median eGFR by the Jelliffe and KeGFR equations was less than the median mGFR, indicating that these equations underestimated the mGFR. On Bland-Altman plots, the Jelliffe and KeGFR equations displayed a considerable lack of agreement with mGFR, with limits of agreement >40 mL/min/1.73 m2. Both equations performed better in CKD and the KeGFR performed better in older patients. Results were similar across AKI stages. CONCLUSIONS: In our study, the Jelliffe and KeGFR equations had good correlations with mGFR; however, they had wide limits of agreement. Further studies are needed to optimize the prediction of mGFR with estimatation equations.

Effective Dose in Nuclear Medicine Studies and SPECT/CT: Dosimetry Survey Across Quebec Province.

The aims of the current study were to draw a portrait of the delivered dose in selected nuclear medicine studies in Québec province and to assess the degree of change between an earlier survey performed in 2010 and a later survey performed in 2014. Methods: Each surveyed nuclear medicine department had to complete 2 forms: the first, about the administered activity in selected nuclear medicine studies, and the second, about the CT parameters used in SPECT/CT imaging, if available. The administered activities were converted into effective doses using the most recent conversion factors. Diagnostic reference levels were computed for each imaging procedure to obtain a benchmark for comparison. Results: The distributions of administered activity in various nuclear medicine studies, along with the corresponding distribution of the effective doses, were determined. Excluding 131I for thyroid studies, 67Ga-citrate for infectious workups, and combined stress and rest myocardial perfusion studies, the remainder of the 99mTc-based studies delivered average effective doses clustered below 10 mSv. Between the 2010 survey and the 2014 survey, there was a statistically significant decrease in delivered dose from 18.3 to 14.5 mSv. 67Ga-citrate studies for infectious workups also showed a significant decrease in delivered dose from 31.0 to 26.2 mSv. The standardized CT portion of SPECT/CT studies yielded a mean effective dose 14 times lower than the radiopharmaceutical portion of the study. Conclusion: Between 2010 and 2014, there was a significant decrease in the delivered effective dose in myocardial perfusion and 67Ga-citrate studies. The CT portions of the surveyed SPECT/CT studies contributed a relatively small fraction of the total delivered effective dose.

Malignant peripheral nerve sheath tumours of the pericardium in a patient with Neurofibromatosis type 1: The diagnostic value of 18F-FDG PET-CT and I-123 MIBG SPECT-CT.

A 25 year old female with known neurofibromatosis type 1 with a large anterior mediastinal mass was investigated. F18-FDG PET-CT revealed a radiotracer avid anterior mediastinal mass with SUVmax of 4.3 and demonstrating a hypoactive center. The Iodine-123 MIBG SPECT-CT study performed subsequently did not demonstrate any uptake, thereby excluding for the most part the diagnoses of paraganglioma or neuroblastoma. At final pathology, a malignant peripheral nerve sheath tumour (MPNST) of the pericardium with areas of chondrosarcomatous and angiosarcomatous differentiation was diagnosed.

Comparison of Accuracy Between 13C- and 14C-Urea Breath Testing: Is an Indeterminate-Results Category Still Needed?

Helicobacter pylori infection is the leading cause of peptic ulcer disease. The purpose of this study was, first, to assess the difference in the distribution of negative versus positive results between the older 14C-urea breath test and the newer 13C-urea breath test and, second, to determine whether use of an indeterminate-results category is still meaningful and what type of results should trigger repeated testing. Methods: A retrospective survey was performed of all consecutive patients referred to our service for urea breath testing. We analyzed 562 patients who had undergone testing with 14C-urea and 454 patients who had undergone testing with 13C-urea. Results: In comparison with the wide distribution of negative 14C results, negative 13C results were distributed farther from the cutoff and were grouped more tightly around the mean negative value. Distribution analysis of the negative results for 13C testing, compared with those for 14C testing, revealed a statistically significant difference between the two. Within the 13C group, only 1 patient could have been classified as having indeterminate results using the same indeterminate zone as was used for the 14C group. This is significantly less frequent than what was found for the 14C group. Discussion: Borderline-negative results do occur with 13C-urea breath testing, although less frequently than with 14C-urea breath testing, and we will be carefully monitoring differences falling between 3.0 and 3.5 %Δ. 13C-urea breath testing is safe and simple for the patient and, in most cases, provides clearer positive or negative results for the clinician.

Detection of Intrathoracic Bleeding by 99mTc-Labeled Red Blood Cell SPECT/CT After Wedge Biopsy of Pulmonary Angiosarcoma.

A 52-y-old man presenting with dyspnea and a massive effusion in the right pleural cavity underwent wedge biopsies of pulmonary lesions found on thoracic CT, leading to a diagnosis of pleural angiosarcoma. Bleeding developed postoperatively and was investigated using pulmonary CT angiography, which failed to identify a site of active bleeding. (99m)Tc-labeled red blood cell (RBC) SPECT/CT of the chest was performed, and the site was rapidly located. To our knowledge, this is the first case reported in the literature of localization of intrathoracic bleeding using (99m)Tc-RBC SPECT/CT.

The relative value of 18F-FDG PET interpretation criteria in generating a probabilistic approach for characterization of pulmonary nodules.

PURPOSE: The evaluation of pulmonary nodules constitutes a large part of PET-CT studies. In this study, we aimed to evaluate the different interpretation criteria in F-fluorodeoxyglucose PET attenuation-corrected and non-attenuation-corrected studies as individual predictors of malignancy in order to propose a useful combination of criteria that can be used in daily practice to classify nodules appropriately. PATIENTS AND METHODS: We performed a historical prospective survey of all consecutive patients referred to our service for the initial assessment of pulmonary nodules and sought the final characterization of these nodules either from tissue sampling or from radiological and clinical follow-up. RESULTS: A total of 104 nodules from 82 patients were included, with a prevalence of malignancy of 53%. Absence of uptake on non-attenuation-corrected studies was found to be the best predictive criterion for benignancy, with a negative predictive value of 97%, and the highest relative risk for malignancy, with a value of 20.9. Uptake higher than that of the mediastinum on attenuation-corrected images was found to be the best criterion for predicting malignancy, with a positive predictive value of 89% and a sensitivity of 73%, which is slightly better than the use of a maximal standardized uptake value cutoff of 3.0. By combining our best negative and positive criteria, we were able to classify 71% (74/104) of the lung nodules with a high level of confidence. More specifically, these two criteria allowed the correct classification of 72% (40/55) of malignant nodules and 57% (28/49) of benign nodules. The 30 remaining nodules were equally distributed in terms of malignancy and had similar characteristics on both PET and CT images. CONCLUSION: A probabilistic approach to pulmonary nodule characterization may help the reading physician to appropriately classify lung nodules into useful categories for the treating physician, moving away from nonstandardized reporting terms.

Metabolic activity measured on PET/CT correlates with clinical outcomes in patients with limb and girdle sarcomas.

OBJECTIVE: To explore the relationship between metabolic activity and outcome in patients with extremity sarcomas. METHODS: Between June 2004 and December 2011, 120 patients with newly diagnosed limb and girdle sarcomas underwent FDG-PET/CT for disease staging prior to curative intent treatment. The maximum standardized uptake value (SUV(max)) was measured for each primary tumor and correlated with outcome. Progression-free survival and overall survival (OS) were analyzed using the Kaplan-Meier method. RESULTS: Soft-tissue sarcomas were more frequent (68%) than bone (27%) or cartilage (5%) tumors. Median follow-up was 33.2 months. 51% of patients progressed during the follow-up interval and 38% died. SUV(max) was dichotomized with a cut-point of 10.3. Patients with SUV(max) < 10.3 had better DFS and OS compared with patients with SUV(max) ≥ 10.3 (P < 0.001 and P < 0.001, respectively [log-rank test]). Multivariate analysis confirmed that even after adjusting for age, sex, site, tumor type (bone vs. soft-tissue), grade, and stage; an SUV(max) ≥ 10.3 correlated with a twofold risk of progression and 2.4 times greater risk of death (hazard ratio [HR] 2.0, 95% CI, 1.1-3.7, and HR, 2.4, 95% CI, 1.1-4.9). CONCLUSION: SUV(max) is an independent adverse prognostic factor for both progression and OS in patients with extremity sarcomas.

Prognostic implication of the lymphangitic carcinomatosis pattern on perfusion lung scan.

PURPOSE: Findings not associated with thromboembolic disease on routine perfusion lung scan may sometimes have particular clinical significance. We wanted to assess the clinical importance and overall survival after the recognition of a lymphangitic carcinomatosis pattern on perfusion lung scan. CASE REPORT: We report a case of lymphangitic carcinomatosis pattern on perfusion lung scan performed in a previously healthy patient who had rapid progressive course and died the next day. METHOD: A Medline search of case reports that describes either lymphangitic carcinomatosis or tumour microemboli on perfusion lung scan. RESULTS: There were a total of 32 patients identified in 21 articles from various countries, including our case. The studied perfusion pattern was reported more often in female patients (81%) was associated with a progressive history of dyspnea (69%) and normal or mild findings on chest radiograph (58%). Of the 29 patients with available outcome data, 79% (23/29) had a progressive course after the lung scan interpretation. In 18 of these 23 cases, the actual interval of survival was given: 67% of these patients (12/18) died within the first month. DISCUSSION: A lymphangitic carcinomatosis perfusion pattern on scintigraphic imaging is associated with a poor prognosis. Nuclear medicine physicians should be aware of this association and that raising the suspicion for a metastatic process may make a difference in the treatment plan of these patients.

FDG PET/CT imaging in primary osseous and soft tissue sarcomas: a retrospective review of 212 cases.

PURPOSE: The aims of this study are to evaluate the sensitivity of FDG PET/CT for detection of soft tissue and osseous sarcomas on the basis of FDG avidity. METHODS: We retrospectively evaluated 212 consecutive patients with known soft tissue or osseous sarcoma who had undergone a FDG PET/CT study for the initial staging or assessment of recurrence of disease. The maximum standardized uptake value (SUVmax) of each primary and/or most intense metastatic lesion was measured and compared with the histological data provided in the final pathological reports. An SUVmax of 2.5 or greater was considered positive for our analysis. RESULTS: Sufficient histopathological data were available for 160 soft tissue sarcomas and 52 osseous sarcomas. FDG PET/CT detected 93.9% of all sarcomas with a sensitivity of 93.7% for soft tissue sarcomas and 94.6% for osseous sarcomas. The sensitivities of the most common sarcoma histologies were 100% for leiomyosarcomas, 94.7% for osteosarcomas, 100% for Ewing's sarcomas, 88.9% for liposarcomas, 80.0% for synovial sarcomas, 100% for gastrointestinal stromal tumors, 87.5% for malignant peripheral nerve sheath tumors, 100% for fibroblastic and myoblastic sarcomas, and 100% for malignant fibrohistiocytic tumors. The receiver-operating characteristic curve revealed an area under the curve of 94% for the discrimination of low-grade and high-grade sarcomas imaged for initial staging by FDG PET/CT. CONCLUSION: The combined metabolic and morphological information of FDG PET/CT imaging allows high sensitivity for the detection of various sarcomas and accurate discrimination between newly diagnosed low-grade and high-grade sarcomas.

Intensity of FDG uptake is not everything: synchronous liposarcoma and fibrous dysplasia in the same patient on FDG PET-CT imaging.

A growing number of studies have demonstrated the usefulness of FDG PET-CT in the preoperative assessment of soft tissue sarcomas. We report a case of a patient with a known low-grade liposarcoma demonstrating only mild hypermetabolism on a FDG PET-CT study. An incidental osseous lesion was found in the distal tibia of the same extremity during the initial workup. This tibial lesion was significantly more intense on the FDG PET-CT study than the primary sarcoma. Further investigation showed this to be an unexpected benign fibrous dysplasia. We present this case as an example of the discrepancy of FDG activity, which may exist between truly malignant and benign lesions that may arise from soft tissue and osseous structures. A benign process should remain in the differential diagnosis for hypermetabolic lesions when evaluating a case of known malignancy, especially when the degree of uptake of that lesion differs significantly from that of the primary lesion.