Jonathan T. Abele

Effect of Hepatic Steatosis on Liver FDG Uptake Measured in Mean Standard Uptake Values

PURPOSE To evaluate the association between diffuse fatty infiltration of the liver and average fluorine 18 fluorodeoxyglucose (FDG) uptake in the liver. MATERIALS AND METHODS Institutional review board approval was obtained for this study; the requirement for informed patient consent was waived. Consecutive nonenhanced whole-body hybrid FDG positron emission tomographic (PET)-computed tomographic (CT) scans obtained in 142 patients (mean age, 63.6 years; age range, 19-94 years) from October 1, 2008, to November 28, 2008, were retrospectively reviewed. Mean attenuation (in Hounsfield units) and standardized uptake value (SUV) measurements for the liver and spleen were obtained, with identical regions of interest used for the CT and PET examinations. The patients were assigned to three study groups: a control group-119 patients with a mean liver attenuation value greater than or equal to the mean spleen attenuation value, a diffuse fatty liver disease group-23 patients in whom the mean liver attenuation value was less than the mean spleen attenuation value, and a more strictly defined fatty liver disease group-a subset of 10 patients from the diffuse fatty liver disease group with a mean liver attenuation value minus mean spleen attenuation value difference of less than or equal to -10 HU. Mean SUV (SUV(m)) values were compared between the groups by using a two-sample t test for means. The association between mean liver attenuation and average FDG uptake was assessed with linear regression analysis. RESULTS The average SUV(m)for the control group was 2.18 (standard deviation [SD], 0.36; 95% confidence interval [CI]: 2.12, 2.24). No significant difference was identified when the average SUV(m)for the control group was compared with those for the fatty liver disease (SUV(m), 2.03; SD, 0.36; 95% CI: 1.90, 2.16) (P >.05) and more strictly defined fatty liver disease (SUV(m), 2.07; SD, 0.24; 95% CI: 1.92, 2.22) groups (P >.05). Linear regression analysis of liver SUV(m)as a function of mean liver attenuation revealed a mean slope of 0.005 (SD, 0.04; 95% CI: -0.005, 0.015) and a correlation coefficient of 0.02. CONCLUSION No association between liver attenuation and FDG uptake measured in terms of SUV(m)was observed. On the basis of these data, it is acceptable to use the liver as a comparator for extrahepatic foci of equivocal increased FDG activity in patients with fatty liver disease. (c) RSNA, 2010.

The clinical significance of incidental intra-abdominal findings on positron emission tomography performed to investigate pulmonary nodules

BackgroundLung cancer is a common cause of cancer-related death. Staging typically includes positron emission tomography (PET) scanning, in which18F-fluoro-2-dexoy-D-glucose (FDG) is taken up by cells proportional to metabolic activity, thus aiding in differentiating benign and malignant pulmonary nodules. Uptake of FDG can also occur in the abdomen. The clinical significance of incidental intraabdominal FDG uptake in the setting of pulmonary nodules is not well established. Our objective was to report on the clinical significance of incidental intra-abdominal FDG activity in the setting of lung cancer.MethodsFifteen hundred FDG-PET reports for studies performed for lung cancer were retrospectively reviewed for the presence of incidental FDG-positive intraabdominal findings. Patient charts with positive findings were then reviewed and information extracted.ResultsTwenty-five patients (25/1500) demonstrated incidental intraabdominal FDG uptake thought to be significant (1.7%) with a mean patient age of 71 years. Colonic uptake was most common (n = 17) with 9 (52%) being investigated further. Of these 9 cases, a diagnosis of malignancy was made in 3 patients, pre-malignant adenomas in 2 patients, a benign lipoma in 1 patient and no abnormal findings in the remaining patients. 8 patients were not investigated further (3 diagnosed with metastatic lung cancer and 2 were of advanced age) secondary to poor prognosis.ConclusionIncidental abdominal findings in the colon on FDG-PET scan for work-up of pulmonary nodules need to be further investigated by colonoscopy.

Metabolic tumour volume as a prognostic factor for oral cavity squamous cell carcinoma treated with primary surgery

BackgroundMetabolic tumour volume (MTV) obtained from pre-treatment 18 F-fluorodeoxydeglucose positron emission tomography with computed tomography (PET-CT) has been validated as an independent predictive factor of outcomes in head and neck cancer patients (HNC) treated with primary chemoradiotherapy (CRT). However its role in patients treated with primary surgery has not yet been studied.ObjectiveTo evaluate the prognostic value of MTV in patients treated with primary surgery for oral cavity squamous cell carcinoma (OCSCC).MethodDemographic and survival data was obtained from patients diagnosed with OCSCC from 2008-2012 in Alberta, Canada. All patients included in the study had PET-CT scan before curative surgical resection. MTV and maximum standardized uptake value (SUVmax) value was delineated from pre-treatment PET-CT scans using Segami Oasis software (Columbus, OH). MTV and SUVmax were divided into intertertile thirds before statistical analysis to allow for in-group comparison of survival.ResultsA total of 80 patients were analyzed using SPSS ver. 20.0 (SPSS Inc, Chicago, IL). Five-year overall, and disease-free survival using Kaplan-Meier curves were 70% and 73% respectively. When the combined SUVmax (tumour primary and locoregional metastasis) was evaluated, it failed to predict overall (HR = 1.0, p = 0.99) or disease-free survival (HR = 1.0, p = 0.227).Conversely an increase in MTV of 17.5 mL (difference between the highest and lowest MTV tertile) was associated with a 12.4 fold increase in risk of disease recurrence (p < 0.001) and an 11.2 fold increase in the risk of death (p < 0.05).ConclusionsThis study shows that MTV is an independent adverse prognostic factor for death and disease recurrence in OCSCC treated with primary surgery.

The Accuracy of Single Photon Emission Computed Tomography/Computed Tomography Arthrography in Evaluating Aseptic Loosening of Hip and Knee Prostheses

Aseptic loosening represents the most common complication associated with hip and knee arthroplasty and is a common indication for surgical revision in the post-arthroplasty population. The optimal imaging methodology in evaluating clinical suspected loosening is not well-defined. Our study retrospectively evaluated nuclear medicine arthrography with hybrid single photon emission computed tomography/computed tomography (SPECT/CT) in 38 patients (21 hip, 17 knee) compared with reference standards of surgical evaluation, spontaneous resolution of symptoms without revision, or a minimum of 1 year clinical and radiographic follow-up. Our study demonstrated a sensitivity of 100%, specificity of 96.0%, PPV of 92.9%, NPV of 100%, and accuracy of 97.4% with this imaging technique suggesting utility of nuclear medicine arthrography with SPECT/CT in the clinical evaluation of suspected aseptic loosening.

Validation of metabolic tumor volume as a prognostic factor for oral cavity squamous cell carcinoma treated with primary surgery

BACKGROUND Despite the promise of metabolic tumor volume (MTV) as a risk-stratifying marker, the retrospective design of the initial study limits its generalizability. Therefore, this study sought to validate MTV as a prognostic factor for oral cavity squamous cell carcinoma (OCSCC) treated with primary surgery within an independent data set. METHODS The validation data set consisted of 42 patients diagnosed with OCSCC between 2008 and 2012. The original cohort consisted of 80 patients. MTV and SUVmax were calculated for the primary tumor and nodal metastasis separately, as well as combined. Before statistical analysis, MTV and SUVmax values were divided into intertertile thirds to allow for intergroup survival analysis. Validation analysis was conducted on the validation data set alone. Data from both cohorts were then combined (n=122) to increase statistical power. RESULTS An increase in combined MTV of 17.5cm(3) was associated with statistically significant increase in risk of disease recurrence (HR=19.2, p<0.001) and death (HR=9.2, p<0.05). Combined SUVmax failed to predict overall (HR=1.0, p>0.05) and disease-free survival (HR=1.0, p>0.05). Increase in the MTV of the primary tumor was associated with an increase in the risk of disease recurrence (HR=21.7, p=0.0001) and risk of death (HR=7.0, p=0.0001), while increase in the MTV of the locoregional neck metastasis was not (p>0.05). An MTV cutoff value of greater than 10.2cm(3) was found to significantly affect survival. CONCLUSION Due to the reproducibility of MTV findings, this study validates MTV as an independent prognostic factor for OCSCC treated with primary surgery.

Bone and Gallium Single-Photon Emission Computed Tomography-Computed Tomography is Equivalent to Magnetic Resonance Imaging in the Diagnosis of Infectious Spondylodiscitis: A Retrospective Study

Objectives Spondylodiscitis has historically been a difficult clinical diagnosis. Two imaging techniques that address this problem are magnetic resonance imaging (MRI) and combined bone (99mTc-methylene diphosphonate) and gallium-67 single-photon emission computed tomography-computed tomography (SPECT-CT). Their accuracies have not been adequately compared. The purpose of this study is to compare the sensitivities and specificities of bone and gallium SPECT-CT and MRI in infectious spondylodiscitis. Methods This retrospective study assessed all patients who underwent a bone or gallium SPECT-CT of the spine to assess for infectious spondylodiscitis from January 1, 2010, to May 2, 2012, at a single tertiary care centre. Thirty-four patients (23 men; average 62 ± 14 years of age) were included. The results of the bone or gallium SPECT-CT were compared against MRI for all patients in the cohort who underwent an MRI within 12 weeks of the SPECT-CT. A diagnosis of spondylodiscitis in the discharge summary was considered the reference standard, and was based on a combination of clinical scenario, response to therapy, imaging, or microbiology. Results Spondylodiscitis was diagnosed in 18 patients and excluded in 16. Bone or gallium SPECT-CT and MRI had similar (P > .05; κ = 0.74) sensitivities (0.94 vs 0.94), specificities (1.00 vs 1.00), positive predictive values (1.00 vs 1.00), negative predictive values (0.94 vs 0.80), and accuracies (0.97 vs 0.95) when compared to the reference standard. Conclusion Although MRI remains the initial modality of choice in diagnosing spondylodiscitis, bone and gallium SPECT-CT appears diagnostically equivalent and should be considered a viable supplementary or alternative imaging modality particularly if there is contraindication or inaccessibility to MRI.

Prostate perfusion mapped by technetium-99m macroaggregated albumin after selective arterial injection.

PURPOSE To determine if perfusion of the prostate can be mapped using technetium-99m ((99m)Tc) macroaggregated albumin (MAA) after selective prostate artery catheterization. MATERIALS AND METHODS Selective prostate artery injections of MAA were performed and analyzed in 14 patients; 9 patients received unilateral injection, and 5 patients received bilateral injections (37 MBq/1 mCi per injection). Fused single-photon emission computed tomography/computed tomography (SPECT/CT) images were subsequently acquired using a fiducial marker technique. Perfusion distribution was assessed, and relative intraprostatic versus extraprostatic activity was quantified and compared between groups. RESULTS The percentage of the prostate gland containing activity was significantly greater for the bilateral injection group compared with the unilateral injection group (76.6% vs 44.3%, P < .05). The percentage of relative intraprostatic versus extraprostatic activity was significantly lower for the bilateral injection group compared with the unilateral injection group (40.3% vs 75.9%, P < .05). Sites of visualized extraprostatic activity included the seminal vesicles (8 of 14 patients), internal iliac vessels (7 of 14 patients), bladder wall (5 of 14 patients), space of Retzius (3 of 14 patients), rectal wall (3 of 14 patients), and penis (1 of 14 patients). CONCLUSIONS Perfusion mapping with (99m)Tc-MAA can be effectively performed with SPECT/CT after selective prostate artery catheterization. The relative percentage of intraprostatic versus extraprostatic activity can be quantified, and the distribution of activity within and outside the prostate gland can be determined.

Streamlining the Imaging of Clinically Suspected Pheochromocytoma: Using Urine Metanephrines to Decrease Imaging Costs

Purpose To improve the cost efficiency of the imaging evaluation of clinically suspected pheochromocytoma by using 24-hour fractionated urine metanephrine (FUM) results. Methods A retrospective review of I-123 meta-iodo-benzyl-guanidine single photon emission tomography (SPECT) computed tomography (CT) studies performed at our institution between January 2007 and February 2011 for clinically suspected pheochromocytoma was performed. SPECT-CT results from 70 patients were compared with results from 24-hour FUM analysis (within 2 months of SPECT-CT) and with relevant CT or magnetic resonance imaging studies (within 6 months of SPECT-CT). An imaging algorithm was developed to maximize cost efficiency without altering the final imaging interpretation. Actual imaging costs for the studied cohort were compared with the expected costs if this algorithm had been applied. Results If the 24-hour FUMs were normal, then all the SPECT-CT studies were negative (16/70). Eighty-seven percent of patients with abnormal total metanephrine had a positive SPECT-CT. If the total metanephrine was normal but 1 or more of the metanephrine fractions were abnormal, then 39%-58% of the SPECT-CT studies were positive. Within this subgroup, none had a positive SPECT-CT if a CT or magnetic resonance image was negative or benign. The actual imaging costs averaged CAD

Association of Fludeoxyglucose F 18–Labeled Positron Emission Tomography and Computed Tomography With the Detection of Oropharyngeal Cancer Recurrence

2833.19 per patient for this cohort. Applying a streamlined imaging algorithm guided by 24-hour FUM analysis would result in an average imaging cost of CAD

Should We Routinely Investigate Incidental Head and Neck Findings on 18-Fluorodeoxyglucose Positron Emission Tomography in Patients Being Staged for Non-small Cell Lung Cancer? A Retrospective Analysis

1225.97 per patient without an expected change in the final imaging impression. Conclusion By using 24-hour FUM results to streamline imaging, considerable cost savings per patient (56.7%) can be attained without a change in the final overall imaging interpretation.