Lesion-based Sensitivity Research Articles

Detectability of Malignant Lesions by Whole-Body Magnetic Resonance Imaging Using Whole-Body Integrated Positron Emission Tomography/Magnetic Resonance Imaging.

To assess the diagnostic ability of whole-body magnetic resonance imaging (MRI) using integrated positron emission tomography/MRI(PET/MRI). Axial T2-weighted image (T2WI), diffusion-weighted imaging (DWI), coronal T1-weighted image (T1WI), axial volumetric interpolated breath-hold examination in the lung field, and 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG-PET) were evaluated in combination with T2WI alone, T2WI + DWI, T2WI + DWI + T1WI, T2WI + DWI + T1WI + volumetric interpolated breath-hold examination (all MRI images), and all MRI + FDG-PET. A total of 370 lesions were observed in 90 (62.5%) of the 144 patients. The lesion-based sensitivities were 62%, 74%, 74%, 76%, and 94%, and the patient-based sensitivities were 70%, 77%, 77%, 77%, and 81% using T2WI, T2WI + DWI, T2WI + DWI + T1WI, all MRI, and all MRI + FDG-PET, respectively. There were significant differences in the lesion-based sensitivity between T2WI and other sequence combinations and between all MRI and all MRI + FDG-PET. No significant differences were observed between any combinations among the patient-based sensitivities. The sensitivity of whole-body MRI was lower when lesion based, but almost equivalent when patient based compared with PET/MRI.

Clinical utility of 68Ga-DOTATOC positron emission tomography/computed tomography for recurrent renal cell carcinoma.

Positron emission tomography (PET)/computed tomography (CT) with 68Ga-labelled 1,4,7,10-tetraazacyclododecane-N,N',N″,N″'-tetraacetic acid-D-Phe1-Tyr3-octreotide (DOTATOC) has been accepted as a diagnostic imaging tool especially for patients with neuroendocrine tumours. However, its clinical usefulness for restaging of renal cell carcinoma (RCC) has not been fully investigated. This retrospective study was performed to elucidate the clinical value of PET/CT using 68Ga-DOTATOC in patients with known or suspected recurrent RCC. We analysed 25 consecutive patients who underwent DOTATOC-PET/CT scans after surgery for RCC (23 clear cell, 1 papillary, 1 unclassified). PET/CT findings were reviewed and the detection rate was calculated on a patient and lesion basis. The detectability was compared in patients who also underwent PET/CT scans with 18F-fluorodeoxyglucose (FDG). Histopathological findings or clinical follow-up were used as the reference standard. Based on the final diagnosis, 76 recurrent or metastatic lesions were confirmed in this population. Of these lesions, 66 lesions in 22 patients were positive by DOTATOC-PET/CT. The patient-based and lesion-based sensitivity was 88% (22/25) and 87% (66/76), respectively. Twelve patients underwent both DOTATOC-PET/CT and FDG-PET/CT. The lesion-based sensitivity of DOTATOC was 74% (20/27), while that of FDG was 59% (16/27). Eight lesions were identified only by DOTATOC, but four lesions from papillary RCC were detected only by FDG. Our data indicate that DOTATOC-PET/CT would be useful for detecting recurrent foci in patients with clear cell RCC. DOTATOC-PET/CT and FDG-PET/CT are considered to have complementary roles.

18 F-FDG PET/MRI vs MRI in patients with recurrent adenoid cystic carcinoma.

To evaluate and compare the diagnostic potential of 18 F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18 FDG-PET/MRI) and MRI for recurrence diagnostics after primary therapy in patients with adenoid cystic carcinoma (ACC). A total of 32 dedicated head and neck 18 F-FDG PET/MRI datasets were included in this analysis. MRI and 18 F-FDG PET/MRI datasets were analyzed in separate sessions by two readers for tumor recurrence or metastases. Lesion-based sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were 96%, 84%, 90%, 93%, and 91% for 18 F-FDG PET/MRI and 77%, 94%, 95%, 73%, and 84% for MRI, resulting in a significantly higher diagnostic accuracy of 18 F-FDG PET/MRI compared to MRI (P < .005). 18 F-FDG PET/MRI is superior to MRI in detecting local recurrence and metastases in patients with ACC of the head and neck. Especially concerning its negative predictive value, 18 F-FDG PET/MRI outperforms MRI.

Staging/restaging performance of F18-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging in breast cancer: A review and meta-analysis

PurposeThis systematic review and meta-analysis was performed to assess the staging/restaging performance of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) in breast cancer. MethodsA comprehensive search was performed in PubMed databases for studies reporting the staging performance of F18-FDG PET/MRI in breast cancer from the inception of these databases to January 29, 2018. Eight studies were included in this systematic review and meta-analysis. Pooled estimates of patient- and lesion-based sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of F18-FDG PET/MRI were calculated alongside 95% confidence intervals (CIs). A summary receiver operating characteristic curve (SROC) was plotted and the area under the SROC curve (AUC) was determined alongside the Q* index. ResultsThe patient-based overall pooled sensitivity, specificity, PLR, NLR, DOR, and AUC of F18-FDG PET/MRI for staging in breast cancer were 0.98 (95% CI, 0.95–0.99), 0.87 (95% CI, 0.76–0.95), 4.59 (95% CI, 1.91–11.05), 0.03 (95% CI, 0.01–0.09), 203.07 (95% CI, 50.33–819.38), and 0.99, respectively. The lesion-based overall pooled sensitivity, specificity, PLR, NLR, DOR, and AUC of F18-FDG PET/MRI for staging in breast cancer were 0.91 (95% CI, 0.88–0.94), 0.95 (95% CI, 0.92–0.97), 11.28 (95% CI, 4.25–29.96), 0.07 (95% CI, 0.02–0.22), 286.46 (95% CI, 64.15–1279.17), and 0.99, respectively. The overall diagnostic accuracies (Q* index) of the staging performance of F18-FDG PET/MRI in breast cancer were 0.96 (patient-based analysis) and 0.95 (lesion-based analysis). ConclusionF18-FDG PET/MRI has excellent diagnostic staging/restaging performance in patients with breast cancer, and thus should be considered for staging of patients with breast cancer.

Diagnostic value of 18F-FDG PET/MRI for the detection of lymph node metastasis in gynecologic cancer.

e17014 Background: Integrated PET/MRI simultaneously provides the metabolic (PET) and functional (DWI) information. It may provide high diagnostic performance in gynecologic malignancies due to the excellent soft tissue contrast. However, up to the present date, only a few studies have shown the diagnostic value of PET/MRI in gynecologic cancer. The aim of our study was to clarify the diagnostic ability of PET/MRI for the detection of lymph node metastasis which can correlate to the prognosis of gynecologic cancer patients. Methods: Eighteen patients with a primary or a suspected recurrent gynecologic cancer (cervical, endometrial and ovarian cancer) were included. They underwent preoperative PET/MRI and CT scans. The morphological criterion on CT was based on the size of lymph nodes which was larger than 1.0 cm in the long axis. The PET criterion was based on the positivity which was higher 18F-FDG uptake compared with the surrounding tissue. On DWI, lymph node was defined as positive in the presence of higher signal intensity compared with the surrounding tissue. The presence or absence of lymph node metastasis was confirmed by surgical pathology. McNemar test was used for the comparison of the diagnostic ability of lymph node metastasis among PET, DWI and CT. Results: Lesion-based sensitivity, specificity and diagnostic accuracy were 23.8%, 96.9% and 84.0% for CT, 93.75%, 87.50% and 88.46% for DWI and 90.48%, 92.86% and 92.44% for PET. PET had a significantly higher sensitivity (P &lt; 0.001) and a higher accuracy (P &lt; 0.05) than CT for the detection of lymph node metastasis. PET also tended to have a higher specificity compared with DWI (P = 0.074). The combination of PET with DWI correctly detected 2 additional lesions to PET alone. Conclusions: Our results demonstrate that integrated PET/MRI can offer a high diagnostic value for the detection of lymph node metastasis in gyn ecologic cancer. The combination of PET with DWI may provide a higher diagnostic accuracy than two separate devices.

Diagnostic performance of a novel dedicated breast PET scanner with C-shaped ring detectors.

A dedicated breast PET scanner with C-shaped detectors (C scanner) has been newly developed. The purpose of this study was to re-evaluate the diagnostic performance of high-resolution PET images with the new reconstruction conditions, obtained using this C scanner in breast cancer patients, and to compare the standardized uptake values (SUVs) of lesions obtained from the C scanner with those from whole-body PET/computed tomography (CT) (WB PET/CT). A total of 159 female patients with known or suspected breast carcinomas (total 188 lesions: 172 invasive carcinomas; eight noninvasive ductal carcinomas in situ; eight benign lesions) were analysed. All patients underwent a WB PET/CT scan 1 h after the injection of fluorine-18 fluorodeoxyglucose, followed by breast scanning using the C scanner. Attenuation-corrected and scatter-corrected images were reconstructed with new parameters. Using the C scanner, 146 of 180 malignant lesions including five ductal carcinomas in situ were detected, 11 lesions were not detected, and the remaining 23 lesions were outside the field of view. The lesion-based sensitivity of the C scanner was 81.1%, and this was increased to 93.0% after excluding lesions outside the field of view; the sensitivity of WB PET/CT was 90.4%. The average maximum SUV of lesions obtained using the C scanner was 9.8±7.0, which was ∼1.6-fold larger than that obtained using WB PET/CT (6.1±4.2). There was no significant difference in breast cancer detectability in this population. The C scanner demonstrated ∼1.6-fold larger maximum SUV than WB PET/CT.

Longitudinal Computed Tomography Monitoring of Pelvic Bones in Patients With Breast Cancer Using Automated Bone Subtraction Software

The aim of this study was to optimize computed tomography (CT) surveillance of skeletal metastases in patients with breast cancer through the use of osseous subtraction maps between baseline and follow-up examinations created by a novel software algorithm. The new postprocessing algorithm segments the original bone followed by image intensity-based rigid alignment creating gray-shaded maps that highlight focal or diffuse loss or increase in bone attenuation. Institutional review board was obtained for this retrospective data evaluation. A total of 33 consecutive patients (31 female; 2 male; mean age, 59.13 ± 12.68 years; range, 32-81 years) with breast cancer were included, who underwent 143 standardized baseline and follow-up CT examinations between February 2014 and June 2016. We classified bone metastases into lytic, sclerotic, and mixed osseous lesions. Any new osteolysis inside a known sclerotic lesion and enlargement of pre-existing sclerotic lesions were considered to represent progressive disease (PD), whereas no change was classified as stable disease (SD). Results were compared additionally with the course of the disease considering the entire skeleton and other involved organs. Software-created automated bone subtraction maps were compared with conventional CT interpretations of axial 5-mm and coronal 1-mm reformatted images. Region of interest measurements were used to quantify new lesions. Results were validated by clinical and CT follow-up. Reading time was evaluated. Skeletal metastases were present in 17/33 (51%) patients (9 sclerotic, 2 lytic, 6 mixed) at baseline. The use of bone subtraction maps resulted in an overall change of response classification into PD in 9/33 (8.1%) patients. Compared with conventional CT evaluation, the bone subtraction maps disclosed 123 new or enlarging sclerotic and 32 new lytic metastases in 23/33 (30.9%) examinations. Mean attenuation of new bone lesions (sclerotic or lytic) significantly increased or decreased (P < 0.01) in all patients. Bone attenuation in pelvic areas without evident metastatic disease significantly increased in patients with PD (P = 0.019), whereas there was no change in SD (P = 0.076). Lesion-based sensitivity, specificity, accuracy, positive predictive values, and negative predictive values were 98.7%, 79.5%, 94.5%, 95.1%, and 94.5%, respectively. Interobserver agreement was good (κ = 0.80; P = 0.077). Reading time was significantly faster for the bone subtraction maps versus 5-mm axial images (P < 0.001). Longitudinal bone subtraction maps increase the accuracy and efficiency of CT diagnosis of skeletal metastases in patients with breast cancer.

An Audit on the Role of PET/CT in Recurrent Ovarian Cancer in a Tertiary Care Centre

Ovarian cancers tend to recur in 50–70 % cases. Metastases from ovarian cancer primarily involve the peritoneum rather than parenchymal sites; thus, the presence of small-volume recurrence or metastatic deposits on the visceral surfaces poses a challenge for interpretation of CT and MR images. PET/CT utilizes its property of higher accumulation in malignant cells to provide both anatomic and functional information for diagnosing malignant tumors. The objectives of the study were to find the correlation between PET/CT findings and final histopathological diagnosis in suspected ovarian cancer recurrences. PET/CT was done in cases with rising or above normal CA-125. These patients with abnormal PET/CT findings were taken up for a secondary cytoreductive surgery, and histopathological reports were taken as the standard against which PET/CT positive findings were compared. Of the 52 patients with suspected recurrence, 40 patients with a PET-CT scan with findings suggestive of an avid uptake underwent surgery. Of the 40 patients who underwent a secondary cytoreductive surgery, 38 had histopathologically confirmed recurrence. PET-CT detected a total of 86 lesions, of which 38 were in the lymph nodes, 32 were peritoneal lesions and 14 were pelvic, 2 were metastatic in the parenchyma of liver. Mean diameter of the lesions detected was 2.2 cm (range 0.3–6.2 cm). PET-CT accurately identified 72 of the 80 histopathologically proven lesions. The overall lesion-based sensitivity of PET-CT is 90 %, specificity 66.7 %, positive predictive value being 83.7 % and negative predictive value 77.7 % and the overall accuracy being 81.9 %. Correlation between PET/CT and histopathological disease: κ (Cohen value) = 0.88 suggests excellent correlation. Selected patients with ovarian cancer recurrence may benefit from PET-CT at the time of even no. or minimal CA-125 elevation by early detection and successful cytoreduction.

Clinical Utility of Tc-99m MIBI SPECT/CT for Preoperative Localization of Parathyroid Lesions.

We aimed to demonstrate the role of SPECT/CT in preoperative localization of parathyroid lesions in patients with hyperparathyroidism who had technetium-99m (Tc-99m) methoxyisobutylisonitrile (MIBI) dual-phase parathyroid scintigraphy. We evaluated retrospectively the scintigraphic data of 103 patients who had parathyroidectomy after Tc-99m MIBI dual-phase parathyroid scintigraphy with SPECT/CT. The planar and SPECT/CT images were evaluated separately to determine their efficacy in localizing parathyroid lesions. These results were then compared with surgical data. There were 84 female and 19 male patients whose mean age was 54 ± 12years. A total of 115 parathyroid lesions in 103 patients were resected during operations. In 87 patients, with both planar and SPECT/CT images, a total of 100 lesions could be detected correctly. In 11 patients, only SPECT/CT images could show 13 subcentimetric lesions. In three patients, three lesions were evaluated as parathyroid lesions both with planar and SPECT/CT images, but according to histopathologic evaluation, they came out to be nonparathyroidal lesions. In two patients, two parathyroid lesions could not be detected preoperatively neither with planar nor with SPECT/CT images. The lesion-based sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87 %, 99 %, 97.1 %, 95.3 %, and 95.8% for planar images and 98.3 %, 99 %, 97.4 %, 99.4 %, and 98.8% for SPECT/CT images, respectively. Tc-99m MIBI parathyroid scintigraphy should be a diagnostic modality of choice in preoperative evaluation of patients with hyperparathyroidism. SPECT/CT has an incremental value both in demonstrating subcentimetric lesions and in accurately localizing lesions anatomically.

CT imaging of bone and bone marrow infiltration in malignant melanoma—Challenges and limitations for clinical staging in comparison to 18FDG-PET/CT

Rationale of this study was the evaluation of the diagnostic value of computed tomography (CT) in the detection of bone marrow infiltration in comparison to PET/CT.Fifty patients (age 61±15.12years) with metastatic malignant melanoma underwent 18F-FDG-PET/CT, including contrast-enhanced CT. 2 readers evaluated the CT images in consensus for bone and bone marrow lesions focusing on lesion location, type and size. PET/CT was used as reference standard to estimate sensitivity, specificity, negative and positive predictive value. Moreover, the bone marrow density was estimated in the long bones and the sacral bone. Serum hamoglobin, thrombocyte level and S100 protein were correlated with the presence or absence of bone and bone marrow lesions.According to PET/CT as standard of reference, of 594 bone and medullary lesions 495 were considered malignant. Of these 77.8% were medullary, 20.4% lytic, 1% sclerotic and 0.8% mixed lytic/sclerotic. Contrast-enhanced CT yielded a lesion-based sensitivity of 36.8% and a specificity of 87.9% (PPV 93.8%; NPV 21.8%). Patient-based sensitivity and specificity were 78.8% and 82.4%, respectively. Of the missed lesions, most were medullary (95.8%). A disseminated bone marrow involvement (defined as >10 bone marrow lesions or diffuse infiltration of a whole body segment) was described in 11 cases, in 6 cases the disseminated involvement was underestimated or missed on CT. In cases with disseminated bone marrow involvement the bone marrow density was significantly higher in the humerus (p=0.04), but not in the femur or sacral bone (p=0.06). Multivariate analysis revealed no isolated effect of bone metastases on S100 serum and hemoglobin level, but both were significantly altered in patients with disseminated bone marrow involvement (p<0.05).In conclusion, the diagnostic value of computed tomography for the detection of bone marrow metastases in patients with melanoma, is limited. Especially in cases with disseminated bone marrow involvement about 50% of the cases were missed or underestimated.

(18)F-DOPA PET/CT in the diagnosis and localization of persistent medullary thyroid carcinoma.

To evaluate the performance of (18)F-L-dihydroxyphenylalanine ((18)F-DOPA) PET/CT in the detection of locoregional and distant medullary thyroid carcinoma (MTC) metastases and to compare imaging findings with histological data. We retrospectively evaluated 86 MTC patients with persistently high serum calcitonin levels after initial surgery who had undergone (18)F-DOPA PET/CT between January 2007 and December 2014 in two referral centres. They were followed up for at least 6months after the PET/CT assessment. The results were compared with histological data or with the findings obtained during follow-up using a complementary imaging modality. (18)F-DOPA PET/CT was positive in 65 of the 86 patients, corresponding to a patient-based sensitivity of 75.6 %. Distant metastatic disease (M1) was seen in 29 patients including 11 with previously unknown metastases revealed only by PET/CT. Among the 36 patients without distant metastatic spread, 25 had nodal involvement limited to the neck, and 10 of these 25 patients underwent reoperation. The lymph node compartment-based sensitivity of (18)F-DOPA PET/CT was 100 % in the two institutions but lesion-based sensitivity was only 24 %. Preoperative and postoperative median calcitonin levels were 405 pg/mL (range 128-1,960 pg/mL) and 259 pg/mL (range 33-1,516 pg/mL), respectively. None of the patients achieved normalization of serum calcitonin after reoperation. (18)F-DOPA PET/CT enables early diagnosis of a significant number of patients with distant metastasis. It has a limited sensitivity in the detection of residual disease but provides high performance for regional analysis. A surgical compartment-oriented approach could be the approach of choice whatever the number of nodes revealed by (18)F-DOPA PET/CT.

Implementation of FAST-PET/MRI for whole-body staging of female patients with recurrent pelvic malignancies: A comparison to PET/CT

ObjectivesTo compare the diagnostic competence of FAST-PET/MRI and PET/CT for whole-body staging of female patients suspect for a recurrence of a pelvic malignancy. Methods24 female patients with a suspected tumor recurrence underwent a PET/CT and subsequent PET/MRI examination. For PET/MRI readings a whole-body FAST-protocol was implemented. Two readers separately evaluated the PET/CT and FAST PET/MRI datasets regarding identification of all tumor lesions and qualitative assessment of visual lesion-to-background contrast (4-point ordinal scale). ResultsTumor relapse was present in 21 of the 24 patients. Both, PET/CT and PET/MRI allowed for correct identification of tumor recurrence in 20 of 21 cases. Lesion-based sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for the detection of malignant lesions were 82%, 91%, 97%, 58% and 84% for PET/CT and 85%, 87%, 96%, 63% and 86% for PET/MRI, lacking significant differences. Furthermore, no significant difference for lesion-to-background contrast of malignant and benign lesions was found. ConclusionFAST-PET/MRI provides a comparably high diagnostic performance for restaging gynecological cancer patients compared to PET/CT with slightly prolonged scan duration, yet enabling a markedly reduced radiation exposure.

Abstract P5-01-09: Improving specificity and refining diagnostic accuracy of MRI in breast cancer with dedicated breast PET (dbPET)

Abstract BACKGROUND. Continued progress in the control of breast cancer will require sustained efforts to provide high-quality screening, diagnosis, and treatment to all segments of the population. MRI has the advantages of providing a 3D view of the breast with high sensitivity, using non-ionizing radiation. However, MRI has significant limitations including its moderate specificity that, in combination with high sensitivity, often leads to unnecessary biopsies. Recently, the MAMmography with Molecular Imaging (MAMMI) dedicated breast PET (dbPET) has emerged as an additional imaging tool for breast cancer diagnosis, clarification of complex lesions and therapy follow-up. It is well known that 18F-FDG-PET has high specificity by assessing metabolic activity, potentially reducing the number of false positive findings. To compare FDG-dbPET with the conventional magnetic resonance imaging (MRI) on breast lesion characterization, we analyzed sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of 37 cases of patients with BC using both dbPET and MRI. METHODS. Thirty-seven women with known or suspected breast carcinoma (41 lesions: 36 invasive carcinomas, 2 noninvasive carcinomas, 1 case of ductal hyperplasia, and 2 benign lesions) were enrolled in this study. Both a prone dbPET Mammi scan, and routine breast MRI scans were performed. A joint reading of MRI and PET scans side-by-side by a nuclear medicine physician and a radiologist was performed. Sensitivity and specificity of MRI and dbPET scans were calculated on the basis of post-surgical pathology reports. Breast MRI examinations were performed in a 1.5-T or 3-T commercial imager (Siemens Medical Solutions) with the use of a dedicated breast coil. The imaging sequence included a sagittal T1-weighted localizing sequence followed by a sagittal T2- weighted sequence. A T1-weighted 3D, fat-suppressed fast spoiled-gradient-echo sequence was then performed with an injection of 0.1 mmol per kilogram body weight of gadolinium dimeglumine (Magnevist; Schering). A prone position high-resolution dedicated breast PET was performed 60 min after administration of 90-120 MBq of 18F-FDG. RESULTS. A total of 41 lesions were assessed. Lesion size range was 0.2 to 7.6 cm. In lesion-by-lesion analysis, sensitivity and specificity of MRI alone were 91% and 54%, respectively; while lesion-based sensitivity of dbPET was 93% and breast-based specificity was 100%. The positive predictive value and the negative predictive value for MRI alone were 69% and 85%, respectively; and for dbPET were 100% and 89%, respectively. In a significant number of cases, dbPET helped to clarify or disprove positive findings by MRI, and in four cases helped to define new positives that had gone unnoticed at MRI, CONCLUSION: Dedicated breast PET scans increase the specificity of MRI. False positives, one of the most challenging aspects of MRI in breast lesions, are reduced. The results of the current study show that FDG-dbPET is more effective than MRI in detecting true breast cancer positives. Its functional information may improve the likelihood of a successful excision, reduce costs from additional procedures, and minimize discomfort and anxiety for the patient. Citation Format: Ines Dominguez, Michel Herranz, Sze Yiun Teo, Elena Brozos, Carmela Rodriguez, Jasper Chaal, Juan Cueva, Jose Ramon Antúnez, Gabriel Gonzalez Pavón, Marielle Fortier, Rafael López, Alvaro Ruibal. Improving specificity and refining diagnostic accuracy of MRI in breast cancer with dedicated breast PET (dbPET) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-01-09.

Probabilistic multiple sclerosis lesion classification based on modeling regional intensity variability and local neighborhood information.

In this paper, a fully automatic probabilistic method for multiple sclerosis (MS) lesion classification is presented, whereby the posterior probability density function over healthy tissues and two types of lesions (T1-hypointense and T2-hyperintense) is generated at every voxel. During training, the system explicitly models the spatial variability of the intensity distributions throughout the brain by first segmenting it into distinct anatomical regions and then building regional likelihood distributions for each tissue class based on multimodal magnetic resonance image (MRI) intensities. Local class smoothness is ensured by incorporating neighboring voxel information in the prior probability through Markov random fields. The system is tested on two datasets from real multisite clinical trials consisting of multimodal MRIs from a total of 100 patients with MS. Lesion classification results based on the framework are compared with and without the regional information, as well as with other state-of-the-art methods against the labels from expert manual raters. The metrics for comparison include Dice overlap, sensitivity, and positive predictive rates for both voxel and lesion classifications. Statistically significant improvements in Dice values ( ), for voxel-based and lesion-based sensitivity values ( ), and positive predictive rates ( and respectively) are shown when the proposed method is compared to the method without regional information, and to a widely used method [1]. This holds particularly true in the posterior fossa, an area where classification is very challenging. The proposed method allows us to provide clinicians with accurate tissue labels for T1-hypointense and T2-hyperintense lesions, two types of lesions that differ in appearance and clinical ramifications, and with a confidence level in the classification, which helps clinicians assess the classification results.

Is 18F-fluorocholine-positron emission tomography/computerized tomography a new imaging tool for detecting hyperfunctioning parathyroid glands in primary or secondary hyperparathyroidism?

Preoperative ultrasonography and scintigraphy using (99m)Tc-sestamibi are commonly used to localize abnormal parathyroid glands. In cases of discrepant results between scintigraphy and ultrasonography, it is important to rely on another diagnostic imaging modality. (18)F-fluorodeoxyglucose (FDG) and (11)C-methionine positron emission tomography (PET) have been studied, but are imperfect to detect abnormal parathyroid glands. Recently, first cases of abnormal parathyroid glands taking-up radiolabelled choline were discovered incidentally in men referred to (11)C-choline or (18)F-fluorocholine (FCH)-PET/CT for prostate cancer. We checked if FCH uptake was a general feature of adenomatous or hyperplastic parathyroid glands. FCH-PET/CT was performed in 12 patients with primary (n = 8) or secondary hyperparathyroidism (1 dialyzed, 3 grafted) and with discordant or equivocal results on preoperative ultrasonography (US) and/or (123)I/(99m)Tc-sestamibi dual-phase scintigraphy. The results of the FCH-PET/CT were evaluated, with surgical exploration and histopathologic examination as the standard of truth. On a per-patient level, the detection rate of FCH-PET/CT (at least one FCH focus corresponding to an abnormal parathyroid gland in a given patient) was 11/12 = 92%. FCH-PET/CT detected 18 foci interpreted as parathyroid glands and correctly localized 17 abnormal parathyroid glands (7 adenomas and 10 hyperplasias). On a per-lesion level, FCH-PET/CT results were 17 TP, 2 false negative ie, a lesion-based sensitivity of 89%, and 1 false positive. As the main result of this pilot study, we show that in patients with hyperparathyroidism and with discordant or equivocal results on scintigraphy or on ultrasonography, adenomatous or hyperplastic parathyroid glands can be localized by FCH-PET/CT with good accuracy. Furthermore, FCH-PET/CT can solve discrepant results between preoperative ultrasonography and scintigraphy and has thus a potential as a functional imaging modality in the detection of abnormal parathyroid glands. Our preliminary results are encouraging and prompt us to further evaluate FCH-PET/CT as a functional imaging agent in patients with biochemical hyperparathyroidism.

Prospective assessment of 18F-FDG PET/CT in detection of recurrent ovarian cancer

ObjectiveTo assess the use of positron emission tomography (PET)/computed tomography (CT) in patients with suspected ovarian cancer recurrence and describe the distribution of metastasis. Patients and methodsThis study included (39) patients suspected to have recurrent ovarian malignancy. This suspicion was either clinically, radiologically or due to raised CA-125 levels. All patients underwent 18F-FDG PET/CT, surgery was performed within 8weeks of imaging studies. Surgical and/or histopathological examinations were available in 31 patients, and clinical, radiological and CA 125 serum level follow up in 8 patients. ResultsThe overall lesion-based sensitivity, specificity, and accuracy of PET/CT for revealing recurrent ovarian carcinoma were 90%, 98% and 97%, respectively. The patient – based sensitivity, specificity, and accuracy of PET/CT were 97%, 75% and 95%, respectively. Conclusion18F-FDG PET/CT is a useful tool for evaluating the recurrence of ovarian cancer after first-line therapy in patients with a high risk of relapse, equivocal radiologic findings, increased or normal levels of serum CA-125. It can more accurately diagnose and localize recurrence, hence decreasing the rate of second look surgery and changing treatment plan.

Role of choline PET/CT in guiding target volume delineation for irradiation of prostate cancer

Choline PET/CT has shown limitations for the detection of primary prostate cancer and nodal metastatic disease, mainly due to limited sensitivity and specificity. Conversely in the restaging of prostate cancer recurrence, choline PET/CT is a promising imaging modality for the detection of local regional and nodal recurrence with an impact on therapy management. This review highlights current literature on choline PET/CT for radiation treatment planning in primary and recurrent prostate cancer. Due to limited sensitivity and specificity in differentiating between benign and malignant prostatic tissues in primary prostate cancer, there is little enthusiasm for target volume delineation based on choline PET/CT. Irradiation planning for the treatment of single lymph node metastases on the basis of choline PET/CT is controversial due to its limited lesion-based sensitivity in primary nodal staging. In high-risk prostate cancer, choline PET/CT might diagnose lymph node metastases, which potentially can be included in the conventional irradiation field. Prior to radiation treatment of recurrent prostate cancer, choline PET/CT may prove useful for patient stratification by excluding distant disease which would require systemic therapy. In patients with local recurrence, choline PET/CT can be used to delineate local sites of recurrence within the prostatic resection bed allowing a boost to PET-positive sites. In patients with lymph node metastases outside the prostatic fossa and regional metastatic lymph nodes, choline PET/CT might influence radiation treatment planning by enabling extension of the target volume to lymphatic drainage sites with or without a boost to PET-positive lymph nodes. Further clinical randomized trials are required to assess treatment outcomes following choline-based biological radiation treatment planning in comparison with conventional radiation treatment planning.

18F-Fluorodihydroxyphenylalanine vs other radiopharmaceuticals for imaging neuroendocrine tumours according to their type

6-Fluoro-(18F)-L-3,4-dihydroxyphenylalanine (FDOPA) is an amino acid analogue for positron emission tomography (PET) imaging which has been registered since 2006 in several European Union (EU) countries and by several pharmaceutical firms. Neuroendocrine tumour (NET) imaging is part of its registered indications. NET functional imaging is a very competitive niche, competitors of FDOPA being two well-established radiopharmaceuticals for scintigraphy, 123I-metaiodobenzylguanidine (MIBG) and 111In-pentetreotide, and even more radiopharmaceuticals for PET, including fluorodeoxyglucose (FDG) and somatostatin analogues. Nevertheless, there is no universal single photon emission computed tomography (SPECT) or PET tracer for NET imaging, at least for the moment. FDOPA, as the other PET tracers, is superior in diagnostic performance in a limited number of precise NET types which are currently medullary thyroid cancer, catecholamine-producing tumours with a low aggressiveness and well-differentiated carcinoid tumours of the midgut, and in cases of congenital hyperinsulinism. This article reports on diagnostic performance and impact on management of FDOPA according to the NET type, emphasising the results of comparative studies with other radiopharmaceuticals. By pooling the results of the published studies with a defined standard of truth, patient-based sensitivity to detect recurrent medullary thyroid cancer was 70 % [95 % confidence interval (CI) 62.1–77.6] for FDOPA vs 44 % (95 % CI 35–53.4) for FDG; patient-based sensitivity to detect phaeochromocytoma/paraganglioma was 94 % (95 % CI 91.4–97.1) for FDOPA vs 69 % (95 % CI 60.2–77.1) for 123I-MIBG; and patient-based sensitivity to detect midgut NET was 89 % (95 % CI 80.3–95.3) for FDOPA vs 80 % (95 % CI 69.2–88.4) for somatostatin receptor scintigraphy with a larger gap in lesion-based sensitivity (97 vs 49 %). Previously unpublished FDOPA results from our team are reported in some rare NET, such as small cell prostate cancer, or in emerging indications, such as metastatic NET of unknown primary (CUP-NET) or adrenocorticotropic hormone (ACTH) ectopic production. An evidence-based strategy in NET functional imaging is as yet affected by a low number of comparative studies. Then the suggested diagnostic trees, being a consequence of the analysis of present data, could be modified, for some indications, by a wider experience mainly involving face-to-face studies comparing FDOPA and 68Ga-labelled peptides.

Comparison of 68Ga-DOTANOC and 68Ga-DOTATATE PET/CT Within Patients with Gastroenteropancreatic Neuroendocrine Tumors

Somatostatin receptor PET tracers such as [(68)Ga-DOTA,1-Nal(3)]-octreotide ((68)Ga-DOTANOC) and [(68)Ga-DOTA,Tyr(3)]-octreotate ((68)Ga-DOTATATE) have shown promising results in patients with neuroendocrine tumors, with a higher lesion detection rate than is achieved with (18)F-fluorodihydroxyphenyl-l-alanine PET, somatostatin receptor SPECT, CT, or MR imaging. (68)Ga-DOTANOC has high affinity for somatostatin receptor subtypes 2, 3, and 5 (sst2,3,5). It has a wider receptor binding profile than (68)Ga-DOTATATE, which is sst2-selective. The wider receptor binding profile might be advantageous for imaging because neuroendocrine tumors express different subtypes of somatostatin receptors. The goal of this study was to prospectively compare (68)Ga-DOTANOC and (68)Ga-DOTATATE PET/CT in the same patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and to evaluate the clinical impact of (68)Ga-DOTANOC PET/CT. Eighteen patients with biopsy-proven GEP-NETs were evaluated with (68)Ga-DOTANOC and (68)Ga-DOTATATE using a randomized crossover design. Labeling of DOTANOC and DOTATATE with (68)Ga was standardized using a fully automated synthesis device. PET/CT findings were compared with 3-phase CT scans and in some patients with MR imaging, (18)F-FDG PET/CT, and histology. Uptake in organs and tumor lesions was quantified and compared by calculation of maximum standardized uptake values (SUVmax) using volume computer-assisted reading. Histology revealed low-grade GEP-NETs (G1) in 4 patients, intermediate grade (G2) in 7, and high grade (G3) in 7. (68)Ga-DOTANOC and (68)Ga-DOTATATE were false-negative in only 1 of 18 patients. In total, 248 lesions were confirmed by cross-sectional and PET imaging. The lesion-based sensitivity of (68)Ga-DOTANOC PET was 93.5%, compared with 85.5% for (68)Ga-DOTATATE PET (P = 0.005). The better performance of (68)Ga-DOTANOC PET is attributed mainly to the significantly higher detection rate of liver metastases rather than tumor differentiation grade. Multivariate analysis revealed significantly higher SUVmax in G1 tumors than in G3 tumors (P = 0.009). This finding was less pronounced with (68)Ga-DOTANOC (P > 0.001). Altogether, (68)Ga-DOTANOC changed treatment in 3 of 18 patients (17%). The sst2,3,5-specific radiotracer (68)Ga-DOTANOC detected significantly more lesions than the sst2-specific radiotracer (68)Ga-DOTATATE in our patients with GEP-NETs. The clinical relevance of this finding has to be proven in larger studies.

Comparison of FDG whole-body PET/CT and gadolinium-enhanced whole-body MRI for distant malignancies in patients with malignant tumors: a meta-analysis

We performed a meta-analysis to compare the performance of whole-body positron emission tomography/computed tomography (WB-PET/CT) with that of whole-body magnetic resonance imaging (WB-MRI) for the overall assessment of distant malignancies in patients with malignant tumors. We performed a meta-analysis of 13 available articles (1239 patients). We calculated sensitivities, specificities, positive likelihood ratios, and negative likelihood ratios, and constructed summary receiver operating characteristic curves using bivariate regression models for WB-PET/CT and WB-MRI, respectively. Across nine studies (1070 patients), WB-PET/CT have similar patient-based sensitivity (0.85 versus 0.85) and specificity (0.96 versus 0.97) with WB-MRI. Across 5 studies (210 patients), WB-PET/CT have similar lesion-based sensitivity (0.85 vs 0.88) and specificity (0.90 vs 0.89) with WB-MRI. Across four studies (511 patients), the combined use may have higher patient-based sensitivity (0.89) than WB-PET/CT (0.82) and WB-MRI (0.81) alone. Both WB-PET/CT and WB-MRI have good diagnostic performance for the overall assessment of distant malignancies in patients with malignant tumors. The combined use may provide more added value than WB-PET/CT and WB-MRI alone.