FDG-PET in Mediastinal Nodal Staging of Non-small Cell Lung Cancer: Correlation of False Results with Histopathologic Finding

PURPOSE

Mediastinal staging of non-small cell lung cancer can be markedly improved by FDG-PET scan, but the problem of false staging of mediastinal nodes by PET scan in non-small cell lung cancer has not yet been overcome. The aim of this study was to identify the mechanism underlying the false staging of mediastinal nodes by FDG-PET in the case of non-small cell lung cancer.

MATERIALS AND METHODS

To evaluate the factors determining the FDG uptake in mediastinal nodes, FDG-PET was performed preoperatively, and mediastinal dissection with pulmonary resection was performed in 62 patients with NSCLC. GLUT-1 expression was studied by immunohistochemistry of the mediastinal nodes (n=111, true positive <TP> 31, true negative <TN> 41, false positive <FP> 27, false negative <FN> 12) using the anti-GLUT-1 antibody. The size, percentage of tumor (tumor ratio), labeling index (rate of stained tumor), staining intensity of the tumor, level of follicular hyperplasia, and staining intensity of the follicle center in the mediastinal node were also studied.

RESULTS

There was no significant difference in size among the 4 nodal groups (TP, TN, FP, FN), nor in the tumor ratio of the metastatic nodes between the TP and FN groups. The labeling index and staining intensity of the TP group were higher than those of the FN group (Mann-Whitney test, p=.001, p=.007) in the case of the metastatic nodes. The level of follicular hyperplasia of the FP group was higher than that of the TN group in the case of the non-metastatic nodes (p=.000).

CONCLUSION

These results suggest that in mediastinal staging of non-small cell lung cancer by FDG-PET, the FN node is associated with low uptake of FDG due to low expression of GLUT-1, and that the FP node is associated with a high level of follicular hyperplasia as a result of there being a reactive change to an inflammatory and/or immune reaction. This is the first report on the mechanism underlying the false results that are sometimes obtained, and which constitute a major problem in the clinical application of FDG-PET to the mediastinal staging of non-small cell lung cancer.

Malignant Peritoneal Mesothelioma Masquerades as Peritoneal Metastasis on (18)F-FDG PET/CT Scans; a Rare Diagnosis that Should Not Be Missed

Malignant peritoneal mesothelioma (MPM) is a rare but fatal tumor. The clinical presentations and imaging findings are nonspecific and resemble various diseases, including peritoneal metastasis. Imaging findings of MPH on (18)F-(18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)/computed tomography (CT) are diverse and not well described. We report the two cases of biopsy-proven MPH using (18)F-FDG PET/CT. In our cases, interesting disease patterns-including MPH arising from visceral peritoneal lining of kidney that suffer from polycystic disease and from the parietal peritoneum beneath the appendectomy scar-were presented. One case showed classical metastases localized within the abdominal cavity; while the other case exhibited the rare pattern of extensive multi-organ metastases. By knowing the possible variations and diagnostic pitfalls of (18)F-FDG PET/CT findings in MPM, more accurate interpretation of such mysterious cancer is attainable.

Hemodynamic Significance of Internal Carotid or Middle Cerebral Artery Stenosis Detected on Magnetic Resonance Angiography

PURPOSE

We evaluated hemodynamic significance of stenosis on magnetic resonance angiography (MRA) using acetazolamide perfusion single photon emission computed tomography (SPECT).

MATERIALS AND METHODS

Of 171 patients, stenosis in internal carotid artery (ICA) and middle cerebral artery (MCA) (ICA-MCA) on MRA and cerebrovascular reserve (CVR) of MCA territory on SPECT was measured using quantification and a 3-grade system. Stenosis and CVR grades were compared with each other, and their prognostic value for subsequent stroke was evaluated.

RESULTS

Of 342 ICA-MCA, 151 (44%) presented stenosis on MRA; grade 1 in 69 (20%) and grade 2 in 82 (24%) cases. Decreased CVR was observed in 9% of grade 0 stenosis, 25% of grade 1, and 35% of grade 2. The average CVR of grade 0 was significantly different from grade 1 (p<0.001) and grade 2 stenosis (p=0.007). In quantitative analysis, average CVR index was -0.56±7.91 in grade 0, -1.81±6.66 in grade 1 and -1.18±5.88 in grade 2 stenosis. Agreement between stenosis and CVR grades was fair in patients with lateralizing and non-lateralizing symptoms (κ=0.230 and 0.346). Of the factors tested, both MRA and CVR were not significant prognostic factors (p=0.104 and 0.988, respectively), whereas hypertension and renal disease were significant factors (p<0.05, respectively).

CONCLUSION

A considerable proportion of ICA-MCA stenosis detected on MRA does not cause CVR impairment despite a fair correlation between them. Thus, hemodynamic state needs to be assessed for evaluating significance of stenosis, particularly in asymptomatic patients.

Comparison of Diagnostic Sensitivity and Quantitative Indices Between (68)Ga-DOTATOC PET/CT and (111)In-Pentetreotide SPECT/CT in Neuroendocrine Tumors: a Preliminary Report

PURPOSE

In-pentetreotide has been used for neuroendocrine tumors expressing somatostatin receptors. Recently, (68)Ga-DOTATOC PET has been used with the advantage of high image quality. In this study, we compared quantitative indices between (111)In-pentetreotide SPECT/CT and (68)Ga-DOTATOC PET/CT.

METHODS

Thirteen patients diagnosed with neuroendocrine tumors were prospectively recruited. Patients underwent (111)In-pentetreotide scans with SPECT/CT and (68)Ga-DOTATOC PET/CT before treatment. The number and location of lesions were analyzed on both imaging techniques to compare lesion detectability. Additionally, the maximal uptake count of each lesion and mean uptake count of the lungs were measured on both imagings, and target-to-normal lung ratios (TNR) were calculated as quantitative indices.

RESULTS

Among 13 patients, 10 exhibited lesions with increased uptake on (111)In-pentetreotide SPECT/CT and/or (68)Ga-DOTATOC PET/CT. Scans with SPECT/CT detected 19 lesions, all of which were also detected on PET/CT. Moreover, 16 additional lesions were detected on PET/CT (6 in the liver, 9 in the pancreas and 1 in the spleen). PET/CT exhibited a significantly higher sensitivity than SPECT/CT (100 % vs. 54 %, P < 0.001). TNR was significantly higher on PET/CT than on SPECT/CT (99.9 ± 84.3 vs. 71.1 ± 114.9, P < 0.001) in spite of a significant correlation (r = 0.692, P = 0.01).

CONCLUSION

Ga-DOTATOC PET/CT has a higher diagnostic sensitivity than (111)In-pentetreotide scans with SPECT/CT. The TNR on PET/CT is higher than that of SPECT/CT, which also suggests the higher sensitivity of PET/CT. (111)In-pentetreotide SPECT/CT should be used carefully if it is used instead of (68)Ga-DOTATOC PET/CT.

Correlation of Asymmetry Indices Measured by Arterial Spin-Labeling MR Imaging and SPECT in Patients with Crossed Cerebellar Diaschisis

BACKGROUND AND PURPOSE

Crossed cerebellar diaschisis, not only a secondary result of supratentorial infarction but also an indicator of clinical outcomes, has frequently been reported on PET and SPECT but has been rarely described with arterial spin-labeling MR imaging. The purpose of this study was to determine the ability of arterial spin-labeling MR imaging to evaluate crossed cerebellar diaschisis compared with that of SPECT. To our knowledge, this is the first study to validate arterial spin-labeling in crossed cerebellar diaschisis by using SPECT as a reference standard.

MATERIALS AND METHODS

This study included 16 patients in whom crossed cerebellar diaschisis was shown on SPECT and 10 control subjects in whom crossed cerebellar diaschisis was not shown on SPECT. During the qualitative analysis, asymmetric cerebellar perfusion on arterial spin-labeling was divided into 1 of the following 3 grades by 2 blinded observers: the affected cerebellum was isointense compared with the unaffected cerebellum (grade I), it was slightly hypointense (grade II), or it was markedly hypointense (grade III). In the quantitative analysis, asymmetry indices were calculated by using SPECT and arterial spin-labeling images. For statistical analysis, κ statistics, the interobserver correlation coefficient, the independent t test, Pearson correlation, and linear regression analysis were used.

RESULTS

Almost all the diagnoses of crossed cerebellar diaschisis on SPECT were noted on arterial spin-labeling in both qualitative and quantitative analyses with good interobserver agreement (κ = 0.961; interobserver correlation coefficient, 0.806). The mean asymmetry index of arterial spin-labeling (26.06 ± 9.00) was significantly larger than that for SPECT (15.28 ± 5.34; P < .001). There was a significant positive correlation between the asymmetry indices obtained for SPECT and those for arterial spin-labeling (r = 0.77 [95% CI, 0.443-0.916]; P < .001). The relationship of asymmetry indices between SPECT and arterial spin-labeling (x, y) was calculated as y = 6.2131 + 1.2986x (R(2) = 0.592; P < .001).

CONCLUSIONS

Arterial spin-labeling can be a noninvasive alternative to SPECT for evaluating crossed cerebellar diaschisis.

PET/CT-Based Dosimetry in 90Y-Microsphere Selective Internal Radiation Therapy: Single Cohort Comparison With Pretreatment Planning on (99m)Tc-MAA Imaging and Correlation With Treatment Efficacy

⁹⁰Y PET/CT can be acquired after ⁹⁰Y-microsphere selective radiation internal therapy (SIRT) to describe radioactivity distribution. We performed dosimetry using ⁹⁰Y-microsphere PET/CT data to evaluate treatment efficacy and appropriateness of activity planning from (99m)Tc-MAA scan and SPECT/CT. Twenty-three patients with liver malignancy were included in the study. (99m)Tc-MAA was injected during planning angiography and whole body (99m)Tc-MAA scan and liver SPECT/CT were acquired. After SIRT using ⁹⁰Y-resin microsphere, ⁹⁰Y-microsphere PET/CT was acquired. A partition model (PM) using 4 compartments (tumor, intarget normal liver, out-target normal liver, and lung) was adopted, and absorbed dose to each compartment was calculated based on measurements from (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT, respectively, to be compared with each other. Progression-free survival (PFS) was evaluated in terms of tumor absorbed doses calculated by (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT results. Lung shunt fraction was overestimated on (99m)Tc-MAA scan compared with ⁹⁰Y-microsphere PET/CT (0.060 ± 0.037 vs. 0.018 ± 0.026, P < 0.01). Tumor absorbed dose exhibited a close correlation between the results from (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT (r = 0.64, P < 0.01), although the result from (99m)Tc-MAA SPECT/CT was significantly lower than that from ⁹⁰Y-microsphere PET/CT (135.4 ± 64.2 Gy vs. 185.0 ± 87.8 Gy, P < 0.01). Absorbed dose to in-target normal liver was overestimated on (99m)Tc-MAA SPECT/CT compared with PET/CT (62.6 ± 38.2 Gy vs. 45.2 ± 32.0 Gy, P = 0.02). Absorbed dose to out-target normal liver did not differ between (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT (P = 0.49). Patients with tumor absorbed dose >200 Gy on ⁹⁰Y-microsphere PET/CT had longer PFS than those with tumor absorbed dose ≤200 Gy (286 ± 56 days vs. 92 ± 20 days, P = 0.046). Tumor absorbed dose calculated by (99m)Tc-MAA SPECT/CT was not a significant predictor for PFS. Activity planning based on (99m)Tc-MAA scan and SPECT/CT can be effectively used as a conservative method. Post-SIRT dosimetry based on ⁹⁰Y-microsphere PET/CT is an effective method to predict treatment efficacy.

Diagnostic values of thyroglobulin measurement in fine-needle aspiration of lymph nodes in patients with thyroid cancer

We aimed to evaluate the diagnostic performance of measuring the concentration of thyroglobulin (Tg) in the washout fluid of the needle aspiration (FNA-Tg). We performed a systematic search of MEDLINE (inception to October 2013) and EMBASE (inception to October 2013) for English publications using keywords "thyroid", "aspiration", "washout", and "thyroglobulin". All searches were limited to human studies. We included studies of FNA-Tg measurement in the washout fluid rinsed with 1 ml of normal saline. Eight studies including 843 lymph nodes (LNs) were eligible for this study. The pooled sensitivity and specificity of preoperative studies are 0.89 [95 % CI 0.82-0.95], 0.60 [0.49-0.70], and those of postoperative studies are 1.0 [0.83-1.0], 1.0 [0.92-1.0]. To determine best cutoffs from each preoperative and postoperative study, the distance between the point (0, 1) and each observed cutoff values (1-specificity, sensitivity) was calculated, and the distance is minimal when the cutoff value of 32.04 for preoperative studies and of 0.9 for postoperative one are selected. FNA-Tg can be used for both preoperative and postoperative evaluation of LN metastasis. Although the cutoff values for the FNA-Tg has not been standardized, preoperative values of 32.04 ng/ml and postoperative values of 0.9 ng/ml are recommended for identifying neck LN metastasis.

Comparison of SPECT/CT and MRI in diagnosing symptomatic lesions in ankle and foot pain patients: diagnostic performance and relation to lesion type

Purpose

The purpose of this study was to compare the diagnostic performance of SPECT/CT and MRI in patients with ankle and foot pain, with regard to the lesion types.

Materials and Methods

Fifty consecutive patients with ankle and foot pain, who underwent ^99mTc-MDP SPECT/CT and MRI, were retrospectively enrolled in this study. Symptomatic lesions were determined based on clinical examination and response to treatment. On MRI and SPECT/CT, detected lesions were classified as bone, ligament/tendon, and joint lesions. Uptake on SPECT/CT was assessed using a 4-grade system. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of SPECT/CT and MRI were evaluated in all detected lesions and each lesion type. Diagnostic value of uptake grade was analyzed using receiver-operating characteristics (ROC) curve analysis, and diagnostic performance was compared using Chi-square or McNemar tests.

Results

In overall lesions, the sensitivity, PPV and NPV of SPECT/CT for symptomatic lesions were 93%, 56%, 91%, and they were 98%, 48%, 95% for MRI. There was no significant difference between SPECT/CT and MRI. However, the specificity of SPECT/CT was significantly higher than that of MRI (48% versus 24%, P = 0.016). Uptake grade on SPECT/CT was significantly higher in symptomatic lesions (P < 0.001), and its area under curve on ROC analysis was 0.787. In the analysis of each lesion type, the specificity of SPECT/CT was poor in joint lesions compared with other lesion types and MRI (P < 0.001, respectively). MRI exhibited lower specificity than SPECT/CT in bone lesions (P = 0.004) and ligament/tendon lesions (P < 0.001).

Conclusions

SPECT/CT has MRI-comparable diagnostic performance for symptomatic lesions in ankle and foot pain patients. SPECT/CT and MRI exhibit different diagnostic specificity in different lesion types. SPECT/CT may be used as a complementary imaging method to MRI for enhancing diagnostic specificity.

Correlation of 11C-methionine PET and diffusion-weighted MRI: is there a complementary diagnostic role for gliomas?

INTRODUCTION

11C-Methionine (MET) PET and diffusion-weighted (DW) MRI are commonly used for evaluation of gliomas. We assessed the correlation between MET uptake and diffusion restriction measured on DW MRI in glioma.

MATERIALS AND METHODS

Thirty-one patients with gliomas, who were initially examined with MET PET and DW MRI, were enrolled retrospectively. MET PET and apparent diffusion coefficient (ADC) images were coregistered to each other, using rigid-body transformation. Tumor-to-normal count density ratio of the cortex (TNR) and normalized apparent diffusion coefficient (nADC) value were measured for each voxel on the MET PET and ADC map. The maximum TNR (TNRmax) and minimum nADC (nADCmin) were obtained for each tumor. Correlations between those parameters were evaluated.

RESULTS

The TNRmax and nADCmin values of a glioma were significantly correlated (r=-0.42). TNRmax and nADCmin were significantly correlated with glioma grades. Furthermore, TNRmax and nADCmin showed a trend for correlation with the Ki-67 index. We analyzed the correlation between voxel-based TNR and ADC within a tumor and observed no correlation between them. Regions with high MET uptake did not correspond with regions with low nADC.

CONCLUSION

We found a negative correlation between TNRmax and nADCmin for each glioma; however, MET uptake and ADC within a tumor were independent of each other and were heterogeneous. The two parameters represent different biological features; thus, as a comprehensive approach, MET PET and DW MRI might have a complementary role in the characterization of gliomas.

Comparison of 4D CT, ultrasonography, and 99mTc sestamibi SPECT/CT in localizing single-gland primary hyperparathyroidism

OBJECTIVE

The present study was designed to evaluate 4D computerized tomography (CT) as a means of localizing abnormal parathyroid glands in primary hyperparathyroidism (HPT).

STUDY DESIGN

Case series with expertized image review.

SETTING

Tertiary care hospital.

SUBJECTS AND METHODS

A total of 38 patients were recruited for study, all of whom had undergone focused parathyroidectomy for single-lesion primary HPT between June 2011 and September 2013. In each patient, 3 imaging procedures were performed: cervical ultrasonography (US), 99mTc-sestamibi SPECT/CT (SeS), and 4D CT. Collective imaging data were blindly reviewed and compared.

RESULTS

4D CT outperformed US and SeS in terms of sensitivity (P=.27), specificity (P=.01), positive predictive value (PPV) (P<.01), negative predictive value (NPV) (P=.19), and accuracy (P<.01). In 7.9% (3/38) of patients, 4D CT provided specific anatomic information that was unaffordable by US and SeS. Localization by 4D CT correlated with tissue parathyroid hormone level (P=.02), maximum diameter (P=.01), and volume (P<.01) of abnormal parathyroid glands.

CONCLUSION

4D CT proved helpful in localizing target parathyroid glands of primary HPT that were missed by traditional imaging.

The value of SPECT/CT in localizing pain site and prediction of treatment response in patients with chronic low back pain

In many circumstances, causing sites of low back pain (LBP) cannot be determined only by anatomical imaging. Combined functional and morphological imaging such as bone scan with single-photon emission computed tomography/computed tomography (SPECT/CT) may be helpful in identifying active lesions. The purpose of this study was to evaluate the usefulness of bone SPECT/CT in localizing the pain site and the treatment of chronic LBP. One hundred seventy-five patients suffering from chronic LBP who underwent SPECT/CT were included, retrospectively. All of the patients received multiple general treatments according to the symptoms, and some of them underwent additional target-specific treatment based on SPECT/CT. Numerical rating scale (NRS) pain score was used to assess the pain intensity. Of 175 patients, 127 showed good response to the given therapies, while the rest did not. Overall, 79.4% of patients with definite active lesions showed good response. Patients with mild active or no lesions on SPECT/CT had relatively lower response rate of 63.0%. Good response was observed by the treatment with the guidance of active lesions identified on SPECT/CT. SPECT/CT could be useful in identifying active lesions in patients with chronic LBP and guiding the clinicians to use adequate treatment.

11C-Pittsburgh B PET imaging in cardiac amyloidosis

OBJECTIVES

This study sought to investigate the efficacy of (11)C-Pittsburgh B (PiB) positron emission tomography (PET)/computed tomography (CT) in the diagnosis of cardiac amyloidosis.

BACKGROUND

The PiB compound has been promising for detection of amyloid deposits in the brain.

METHODS

A total of 22 consecutive patients were enrolled in this prospective pilot study of monoclonal gammopathy patients with suspected cardiac amyloidosis. The study consisted of a series of (11)C-PiB PET/CT, echocardiography, cardiac magnetic resonance, and endomyocardial biopsy within a 1-month period. In addition, 10 normal subjects were recruited to determine the most optimal cut-off value for a positive (11)C-PiB PET/CT scan.

RESULTS

Among the 22 patients, 15 patients were diagnosed as cardiac amyloidosis by endomyocardial biopsy and 5 patients had undergone chemotherapy previously before the (11)C-PiB PET/CT. There were no differences in echocardiographic parameters between patients with versus without cardiac amyloidosis, except for a marginal difference in the left ventricular end-diastolic dimension (median 41.0 mm [range 33.0 to 49.0 mm] vs. 50.0 mm [range 38.0 to 55.0 mm], p = 0.066). (11)C-PiB PET/CT was positive in 13 of 15 biopsy-proven cardiac amyloidosis patients, whereas none of the patients without cardiac amyloidosis demonstrated positive (11)C-PiB PET/CT scan results. The maximal myocardium-to-blood cavity ratio was significantly different between patients with versus without cardiac amyloidosis (median 3.9 [range 1.7 to 19.9] vs. 1.0 [range 0.8 to 1.2], p < 0.001). In association with the significant difference of (11)C-PiB uptake in the myocardium between the chemotherapy naïve versus the previous chemotherapy group (median 10.4 [range 1.7 to 19.9] vs. 2.3 [range 1.7 to 3.8], p = 0.014), all except 1 patient among the 5 previously treated patients had responded to chemotherapy by serum free light chain assay results at the time of (11)C-PiB PET/CT scan.

CONCLUSIONS

(11)C-PiB PET/CT may be valuable for the diagnosis of cardiac amyloidosis noninvasively. Whether (11)C-PiB PET/CT may be a good surrogate marker of active light chain deposition in the myocardium warrants further investigation in a larger number of patients.

Usefulness of Additional SPECT/CT Identifying Lymphatico-renal Shunt in a Patient with Chyluria

Lymphoscintigraphy is known to be a useful and non-invasive modality for the evaluation of lymphatic abnormality. However, lymphoscintigraphy has limitations in evaluating chyluria because of its lack of anatomical information. Additional single-photon emission computed tomography (SPECT) combined with computed tomography (CT) was considered to be potentially helpful in detecting the abnormal lymphatico-renal communication. A 20-year-old male patient was referred to our hospital for evaluation of recurrent chyluria. During the third recurrence of chyluria, additional SPECT/CT along with lymphoscintigraphy was performed for evaluation. From the combined SPECT/CT images, lymphatic drainage of radiotracers to the kidney was well visualized, helping diagnosis of a patient with chyluria.

Prognostic value of volumetric parameters of (18)F-FDG PET in non-small-cell lung cancer: a meta-analysis

PURPOSE

We conducted a comprehensive systematic review of the literature on volumetric parameters from (18)F-FDG PET and a meta-analysis of the prognostic value of metabolic tumour volume (MTV) and total lesion glycolysis (TLG) in patients with lung cancer.

METHODS

A systematic search of MEDLINE and EMBASE was performed using the keywords "positron emission tomography (PET)", "lung cancer", and "volume". Inclusion criteria were: (18)F-FDG PET used as an initial imaging tool; studies limited to non-small-cell lung cancer (NSCLC); volume measurement of lung cancer; patients who had not undergone surgery, chemotherapy, or radiotherapy before the PET scan; and studies that reported survival data. Event-free survival and overall survival were evaluated as outcomes. The impact of MTV and TLG on survival was measured in terms of the hazard ratio (HR) effect size. Data from each study were analysed using Review Manager 5.2.

RESULTS

Thirteen eligible studies including 1,581 patients were analysed. Patients with high MTV showed a worse prognosis with an HR of 2.71 (95% CI 1.82 - 4.02, p < 0.00001) for adverse events and an HR of 2.31 (95% CI 1.54 - 3.47, p < 0.00001) for death. Patients with high TLG also showed a worse prognosis with an HR of 2.35 (95% CI 1.91 - 2.89, p < 0.00001) for adverse events and an HR of 2.43 (95% CI 1.89 - 3.11, p < 0.00001) for death. The prognostic value of MTV and TLG remained significant in a subgroup analysis according to TNM stage as well as the methods for defining cut-off values and tumour delineation.

CONCLUSION

Volumetric parameters from (18)F-FDG PET are significant prognostic factors for outcome in patients with NSCLC. Patients with a high MTV or TLG are at higher risk of adverse events and death. MTV and TLG were significant prognostic factors in patients with TNM stage I/II and stage III/IV NSCLC.

Radioiodine therapy in differentiated thyroid cancer: the first targeted therapy in oncology

Iodide uptake across the membranes of thyroid follicular cells and cancer cells occurs through an active transport process mediated by the sodium-iodide symporter (NIS). The rat and human NIS-coding genes were cloned and identified in 1996. Evaluation of NIS gene and protein expression is critical for the management of thyroid cancer, and several approaches to increase NIS levels have been tried. Identification of the NIS gene has provided a means of expanding its role in radionuclide therapy and molecular target-specific theragnosis (therapy and diagnosis using the same molecular target). In this article, we describe the relationship between NIS expression and the thyroid carcinoma treatment using I-131 and alternative therapeutic approaches.

Feasibility of 18F-FDG PET as a noninvasive diagnostic tool of muscle denervation: a preliminary study

The purpose of this study was to confirm glucose hypermetabolism in denervated muscle and investigate the feasibility of (18)F-FDG PET scanning for the detection of muscle denervation.

METHOD

A sciatic neuropathy model in rats was created by nerve resection of the left sciatic nerve and sham operation on the other side. Eight days after denervation, small-animal PET/CT scans of the hindlimbs were acquired. Muscle denervation was confirmed by electrophysiologic and histologic study.

RESULTS

All rats showed increased (18)F-FDG uptake in the muscles of the left (denervated) lower legs. The calculated maximum lesion-to-normal counts ratio of the left lower leg anterolateral (left, 11.02 ± 2.08; right, 1.81 ± 0.40, n = 6, P < 0.01) and posterior (left, 9.81 ± 4.58; right, 1.87 ± 0.44, n = 6, P < 0.01) compartment were significantly increased. The electrophysiologic and histologic study verified muscle denervation.

CONCLUSION

Glucose hypermetabolism in muscle denervation is an obvious phenomenon. (18)F-FDG PET scanning can be used to visualize muscle denervation.

Autoclustering of Non-small Cell Lung Carcinoma Subtypes on (18)F-FDG PET Using Texture Analysis: A Preliminary Result

PURPOSE

Texture analysis on (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) scan is a relatively new imaging analysis tool to evaluate metabolic heterogeneity. We analyzed the difference in textural characteristics between non-small cell lung carcinoma (NSCLC) subtypes, namely adenocarcinoma (ADC) and squamous cell carcinoma (SqCC).

METHODS

Diagnostic (18)F-FDG PET/computed tomography (CT) scans of 30y patients (median age, 67; range, 42-88) with NSCLC (17 ADC and 13 SqCC) were retrospectively analyzed. Regions of interest were manually determined on selected transverse image containing the highest SUV value in tumors. Texture parameters were extracted by histogram-based algorithms, absolute gradient-based algorithms, run-length matrix-based algorithms, co-occurrence matrix-based algorithms, and autoregressive model-based algorithms. Twenty-four out of hundreds of texture features were selected by three algorithms: Fisher coefficient, minimization of both classification error probability and average correlation, and mutual information. Automated clustering of tumors was based on the most discriminating feature calculated by linear discriminant analysis (LDA). Each tumor subtype was determined by histopathologic examination after biopsy and surgery.

RESULTS

Fifteen texture features had significant different values between ADC and SqCC. LDA with 24 automate-selected texture features accurately clustered between ADC and SqCC with 0.90 linear separability. There was no high correlation between SUVmax and texture parameters (|r| ≤ 0.62).

CONCLUSION

Each subtype of NSCLC tumor has different metabolic heterogeneity. The results of this study support the potential of textural parameters on FDG PET as an imaging biomarker.

Is it Feasible to Use the Commercially Available Autoquantitation Software for the Evaluation of Myocardial Viability on Small-Animal Cardiac F-18 FDG PET Scan?

PURPOSE

To evaluate the reliability of quantitation of myocardial viability on cardiac F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scans with three different methods of visual scoring system, autoquantitation using commercially available autoquantitation software, and infarct-size measurement using histogram-based maximum pixel threshold identification on polar-map in rat hearts.

METHODS

A myocardial infarct (MI) model was made by left anterior descending artery (LAD) ligation in rat hearts. Eighteen MI rats underwent cardiac FDG-PET-computed tomography (CT) twice within a 4-week interval. Myocardium was partitioned into 20 segments for the comparison, and then we quantitated non-viable myocardium on cardiac FDG PET-CT with three different methods: method A-infarct-size measurement using histogram-based maximum pixel threshold identification on polar-map; method B-summed MI score (SMS) by a four-point visual scoring system; method C-metabolic non-viable values by commercially available autoquantitation software. Changes of non-viable myocardium on serial PET-CT scans with three different methods were calculated by the change of each parameter. Correlation and reproducibility were evaluated between the different methods.

RESULTS

Infarct-size measurement, visual SMS, and non-viable values by autoquantitation software presented proportional relationship to each other. All the parameters of methods A, B, and C showed relatively good correlation between each other. Among them, infarct-size measurement (method A) and autoquantitation software (method C) showed the best correlation (r = 0.87, p < 0.001). When we evaluated the changes of non-viable myocardium on the serial FDG-PET-CT- however, autoquantitation program showed less correlation with the other methods. Visual assessment (method B) and those of infarct size (method A) showed the best correlation (r = 0.54, p = 0.02) for the assessment of interval changes.

CONCLUSIONS

Commercially available quantitation software could be applied to measure the myocardial viability on small animal cardiac FDG-PET-CT scan. This kind of quantitation showed good correlation with infarct size measurement by histogram-based maximum pixel threshold identification. However, this method showed the weak correlation when applied in the measuring the changes of non-viable myocardium on the serial scans, which means that the caution will be needed to evaluate the changes on the serial monitoring.

The effectiveness of recombinant human thyroid-stimulating hormone versus thyroid hormone withdrawal prior to radioiodine remnant ablation in thyroid cancer: a meta-analysis of randomized controlled trials

We evaluated the efficacy of recombinant human thyroid-stimulating hormone (rhTSH) versus thyroid hormone withdrawal (THW) prior to radioiodine remnant ablation (RRA) in thyroid cancer. A systematic search of MEDLINE, EMBASE, the Cochrane Library, and SCOPUS was performed. Randomized controlled trials that compared ablation success between rhTSH and THW at 6 to 12 months following RRA were included in this study. Six trials with a total of 1,660 patients were included. When ablation success was defined as a thyroglobulin (Tg) cutoff of 1 ng/mL (risk ratio, 0.99; 95% confidence interval, 0.96-1.03) or a Tg cutoff of 1 ng/mL plus imaging modality (RR 0.97; 0.90-1.05), the results of rhTSH and THW were similar. There were no significant differences when ablation success was defined as a Tg cutoff of 2 ng/mL (RR 1.03; 0.95-1.11) or a Tg cutoff of 2 ng/mL plus imaging modality (RR 1.02; 0.95-1.09). When a negative (131)I-whole body scan was used solely as the definition of ablation success, the effects of rhTSH and THW were not significantly different (RR 0.97; 0.93-1.02). Therefore, ablation success rates are comparable when RRA is prepared by either rhTSH or THW.

Preoperative PET/CT standardized FDG uptake values of pelvic lymph nodes as a significant prognostic factor in patients with endometrial cancer

PURPOSE

Using integrated PET/CT, we evaluated the prognostic relevance of preoperative pelvic lymph node (LN) (18)F-FDG uptake in endometrioid endometrial cancer.

METHODS

We retrospectively reviewed patients with pathologically proven endometrial cancer who underwent preoperative (18)F-FDG PET/CT scans to evaluate the prognostic significance of PET/CT parameters and other clinicopathological variables. We used Cox proportional hazards regression to examine the relationship between recurrence and the maximum standardized uptake value (SUVmax) in pelvic LNs (SUVLN) on FDG PET/CT.

RESULTS

Clinical data, treatment modalities and results were reviewed in 70 eligible patients. The median postsurgical follow-up was 29 months (range 6 to 95 months). Receiver-operating characteristic analysis identified the significant SUVLN cut-off value as 15. The SUVLN correlated with FIGO stage (P < 0.001), LN metastasis (P < 0.001), lymphovascular space invasion (P < 0.001), SUVtumour (P = 0.001), metastatic LN size (P = 0.004), primary tumour size (P = 0.012), tumour grade (P = 0.015) and depth of tumour invasion (P = 0.035). Regression analysis showed a statistically significant association between recurrence and SUVLN (P = 0.002). Recurrence differed significantly (P < 0.001) between patients with SUVLN >15 and those with SUVLN ≤15.

CONCLUSION

Preoperative pelvic LN FDG uptake exhibited a strong significant association with recurrence of endometrioid endometrial cancer.

Prognostic value of metabolic tumor volume and total lesion glycolysis in head and neck cancer: a systematic review and meta-analysis

We conducted a comprehensive systematic review of the literature on volumetric parameters and a meta-analysis of the prognostic value of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in patients with head and neck cancer (HNC).

METHODS

A systematic search of MEDLINE and EMBASE was performed using the key words PET, head and neck, and volume. Inclusion criteria were (18)F-FDG PET used as an initial imaging tool; studies limited to HNC; patients who had not undergone surgery, chemotherapy, or radiotherapy before PET scans; and studies reporting survival data. Event-free survival and overall survival were considered markers of outcome. The impact of MTV or TLG on survival was measured by the effect size hazard ratio (HR). Data from each study were analyzed using Review Manager.

RESULTS

Thirteen studies comprising 1,180 patients were included in this study. The combined HR for adverse events was 3.06 (2.33-4.01, P < 0.00001) with MTV and 3.10 (2.27-4.24, P < 0.00001) with TLG, meaning that tumors with high volumetric parameters were associated with progression or recurrence. Regarding overall survival, the pooled HR was 3.51 (2.62-4.72, P < 0.00001) with MTV and 3.14 (2.24-4.40, P < 0.00001) with TLG. There was no evidence of significant statistical heterogeneity at an I(2) of 0%.

CONCLUSION

MTV and TLG are prognostic predictors of outcome in patients with HNC. Despite clinically heterogeneous HNC and the various methods adopted between studies, we can confirm that patients with a high MTV or TLG have a higher risk of adverse events or death.