The diagnostic value of [<Superscript>18</Superscript>F]FDG PET for the detection of chronic osteomyelitis and implant-associated infection

Purpose

The diagnosis of osteomyelitis and implant-associated infections in patients with nonspecific laboratory or radiological findings is often unsatisfactory. We retrospectively evaluated the contributions of [¹⁸F]FDG PET and [¹⁸F]FDG PET/CT to the diagnosis of osteomyelitis and implant-associated infections, enabling timely and appropriate decision-making for further therapy options.

Methods

[¹⁸F]FDG PET or PET/CT was performed in 215 patients with suspected osteomyelitis or implant-associated infections between 2000 and 2013. We assessed the diagnostic accuracy of both modalities together and separately with reference to intraoperative microbial findings, with a mean clinical follow-up of 69?±?49 months.

Results

Infections were diagnosed clinically in 101 of the 215 patients. PET and PET/CT scans revealed 87 true-positive, 76 true-negative, 38 false-positive, and 14 false-negative results, indicating a sensitivity of 86 %, a specificity of 67 %, a positive predictive value (PPV) of 70 %, a negative predictive value (NPV) of 84 % and an accuracy of 76 %. The sensitivity of PET/CT was 88 %, but specificity, PPV, NPV and accuracy (76 %, 76 %, 89 % and 82 %, respectively) were higher than those of stand-alone PET.

Conclusion

[¹⁸F]FDG PET is able to identify with high sensitivity the presence of osteomyelitis in orthopaedic surgery patients with nonspecific clinical symptoms of infection.

     

Preoperative prediction of microvascular invasion of hepatocellular carcinoma using <Superscript>18</Superscript>F-FDG PET/CT: a multicenter retrospective cohort study

Purpose

The aim of this study was to assess the potential of tumor ¹⁸F-fluorodeoxyglucose (FDG) avidity as a preoperative imaging biomarker for the prediction of microvascular invasion (MVI) of hepatocellular carcinoma (HCC).

Methods

One hundred and fifty-eight patients diagnosed with Barcelona Clinic Liver Cancer stages 0 or A HCC (median age, 57 years; interquartile range, 50–64 years) who underwent ¹⁸F-FDG positron emission tomography with computed tomography (PET/CT) before curative surgery at seven university hospitals were included. Tumor FDG avidity was measured by tumor-to-normal liver standardized uptake value ratio (TLR) of the primary tumor on FDG PET/CT imaging. Logistic regression analysis was performed to identify significant parameters associated with MVI. The predictive performance of TLR and other clinical variables was assessed using receiver operating characteristic (ROC) curve analysis.

Results

MVI was present in 76 of 158 patients with HCCs (48.1%). Multivariable logistic regression analysis revealed that TLR, serum alpha-fetoprotein (AFP) level, and tumor size were significantly associated with the presence of MVI (P?<?0.001). Multinodularity was not significantly associated with MVI (P?=?0.563). The area under the ROC curve (AUC) for predicting the presence of MVI was best with TLR (AUC?=?0.704), followed by tumor size (AUC?=?0.685) and AFP (AUC?=?0.670). We were able to build an improved prediction model combining TLR, tumor size, and AFP by using multivariable logistic regression modeling (AUC?=?0.756).

Conclusions

Tumor FDG avidity measured by TLR on FDG PET/CT is a preoperative imaging biomarker for the prediction of MVI in patients with HCC.

     

Diagnostic Value of <Superscript>18</Superscript>F-FDG PET/CT and MRI in the Preoperative Evaluation of Uterine Carcinosarcoma

Purpose

This study aimed to compare the diagnostic value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and magnetic resonance imaging (MRI) in the preoperative evaluation of uterine carcinosarcoma.

Methods

Fifty-four women with pathologically confirmed uterine carcinosarcoma who underwent preoperative FDG PET/CT and MRI from June 2006 to November 2016 were included. Pathologic findings from primary tumor lesions, para-aortic and pelvic lymph node (LN) areas, and peritoneal seeding lesions were compared with the FDG PET/CT and MRI findings. The maximum standardized uptake value (SUVmax) of the primary tumor and LN was obtained. The tumor-to-liver ratio (TLR) was calculated by dividing the SUVmax of the primary tumor or LN by the mean SUV of the liver.

Results

For detecting primary tumor lesions (n?=?54), the sensitivity and accuracy of FDG PET/CT (53/54) and MRI (53/54) were 98.2%. The sensitivity, specificity, and accuracy of FDG PET/CT versus MRI were as follows: 63.2% (12/19) versus 26.3% (5/19), 100% (35/35) versus 100% (35/35), and 87.0% versus 74.0%, respectively, for pelvic LN areas (p?=?0.016); 85.7% (12/14) versus 42.9% (6/14), 90% (36/40) versus 97.5% (39/40), and 88.9% versus 83.3%, respectively, for para-aortic LN areas (p?=?0.004); and 59.4% (19/32) versus 50% (16/32), 100% (22/22) versus 100% (22/22), and 75.9% versus 70.4%, respectively, for peritoneal seeding lesions (p?=?0.250). For distant metastasis, the sensitivity, specificity, and accuracy of FDG PET/CT were 100 (8/8), 97.8 (45/46), and 98.2%, respectively.

Conclusions

FDG PET/CT showed superior diagnostic accuracy compared to MRI in detecting pelvic and para-aortic LN metastasis in patients with uterine carcinosarcoma. Moreover, FDG PET/CT facilitated the identification of distant metastasis.

     

Prognostic value of <Superscript>18</Superscript>F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with Barcelona Clinic Liver Cancer stages 0 and A hepatocellular carcinomas: a multicenter retrospective cohort study

Purpose

We evaluated the prognostic value of pretreatment ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography (FDG PET/CT) in patients with Barcelona Clinic Liver Cancer (BCLC) stage 0 or A hepatocellular carcinoma (HCC) who had received curative treatment or transarterial chemoembolization (TACE).

Methods

Between 2009 and 2010, 317 patients diagnosed with HCC at seven hospitals were enrolled. Among these, 195 patients underwent curative treatments including resection, liver transplantation, and radiofrequency ablation. TACE was performed in 122 patients. The tumor-to-normal liver standardized uptake value ratio (TLR) of the primary tumor was measured using pretreatment FDG PET/CT. The prognostic significance of TLR and other clinical variables was assessed using Cox regression models. Differences in the overall survival (OS) associated with TLR or other significant clinical factors were examined using the Kaplan-Meier method.

Results

Over a median follow-up period of 46 months, 77 patients died from cancer. In the curative cohort, higher TLR (≥2) was significantly associated with death (hazard ratio [HR]?=?2.68; 95 % CI, 1.16–6.15; P?=?0.020) in multivariable analysis. Patients with a higher TLR had significantly worse OS than patients with a lower TLR (5-year overall survival, 61 % vs. 79.4 %; P?=?0.006). In the TACE cohort, the Model for End-Stage Liver Disease (MELD) score (≥8) was a significant independent prognostic factor for OS (HR?=?3.34; 95 % CI, 1.49–7.48; P?=?0.003), whereas TLR was not associated with OS. The Kaplan-Meier curves showed significantly poorer OS in patients with higher MELD scores (≥8) than in those with lower MELD scores (5-year survival rate, 33.1 % vs. 79.6 %; P?<?0.001).

Conclusions

Pretreatment TLR measured using FDG PET/CT was an independent prognostic factor for OS in patients with BCLC stage 0 or A HCC undergoing curative treatment. In contrast, underlying liver function appeared to be important in predicting the prognosis of patients undergoing TACE.

     

[<Superscript>68</Superscript>Ga]DOTATATE PET/MRI and [<Superscript>18</Superscript>F]FDG PET/CT are complementary and superior to diffusion-weighted MR imaging for radioactive-iodine-refractory differentiated thyroid cancer

Purpose

The purpose of this study was to determine whether [⁶⁸Ga]DOTATATE PET/MRI with diffusion-weighted imaging (DWI) can replace or complement [¹⁸F]FDG PET/CT in patients with radioactive-iodine (RAI)-refractory differentiated thyroid cancer (DTC).

Methods

The study population comprised 12 patients with elevated thyroglobulin and a negative RAI scan after thyroidectomy and RAI remnant ablation who underwent both [¹⁸F]FDG PET/CT and [⁶⁸Ga]DOTATATE PET/MRI within 8 weeks of each other. The presence of recurrent cancer was evaluated on a per-patient, per-organ and per-lesion basis. Histology, and prior and follow-up examinations served as the standard of reference.

Results

Recurrent or metastatic tumour was confirmed in 11 of the 12 patients. [⁶⁸Ga]DOTATATE PET(/MRI) correctly identified the tumour burden in all 11 patients, whereas in one patient local relapse was missed by [¹⁸F]FDG PET/CT. In the lesion-based analysis, overall lesion detection rates were 79/85 (93 %), 69/85 (81 %) and 27/82 (33 %) for [¹⁸F]FDG PET/CT, [⁶⁸Ga]DOTATATE PET/MRI and DWI, respectively. [¹⁸F]FDG PET(/CT) was superior to [⁶⁸Ga]DOTATATE PET(/MRI) in the overall evaluation and in the detection of pulmonary metastases. In the detection of extrapulmonary metastases, [⁶⁸Ga]DOTATATE PET(/MRI) showed a higher sensitivity than [¹⁸F]FDG PET(/CT), at the cost of lower specificity. DWI achieved only poor sensitivity and was significantly inferior to [¹⁸F]FDG PET in the lesion-based evaluation in the detection of both extrapulmonary and pulmonary metastases.

Conclusion

[¹⁸F]FDG PET/CT was more sensitive than [⁶⁸Ga]DOTATATE PET/MRI in the evaluation of RAI-refractory DTC, mostly because of its excellent ability to detect lung metastases. In the evaluation of extrapulmonary lesions, [⁶⁸Ga]DOTATATE PET(/MRI) was more sensitive and [¹⁸F]FDG PET(/CT) more specific. Furthermore, DWI did not provide additional information and cannot replace [¹⁸F]FDG PET for postoperative monitoring of patients with suspected RAI-refractory DTC.

     

Multimodal correlation of dynamic [<Superscript>18</Superscript>F]-AV-1451 perfusion PET and neuronal hypometabolism in [<Superscript>18</Superscript>F]-FDG PET

Purpose

Cerebral glucose metabolism measured with [18F]-FDG PET is a well established marker of neuronal dysfunction in neurodegeneration. The tau-protein tracer [18F]-AV-1451 PET is currently under evaluation and shows promising results. Here, we assess the feasibility of early perfusion imaging with AV-1451 as a substite for FDG PET in assessing neuronal injury.

Methods

Twenty patients with suspected neurodegeneration underwent FDG and early phase AV-1451 PET imaging. Ten one-minute timeframes were acquired after application of 200 MBq AV-1451. FDG images were acquired on a different date according to clinical protocol. Early AV-1451 timeframes were coregistered to individual FDG-scans and spatially normalized. Voxel-wise intermodal correlations were calculated on within-subject level for every possible time window. The window with highest pooled correlation was considered optimal. Z-transformed deviation maps (ZMs) were created from both FDG and early AV-1451 images, comparing against FDG images of healthy controls.

Results

Regional patterns and extent of perfusion deficits were highly comparable to metabolic deficits. Best results were observed in a time window from 60 to 360 s (r = 0.86). Correlation strength ranged from r = 0.96 (subcortical gray matter) to 0.83 (frontal lobe) in regional analysis. ZMs of early AV-1451 and FDG images were highly similar.

Conclusion

Perfusion imaging with AV-1451 is a valid biomarker for assessment of neuronal dysfunction in neurodegenerative diseases. Radiation exposure and complexity of the diagnostic workup could be reduced significantly by routine acquisition of early AV-1451 images, sparing additional FDG PET.

     

Evaluation of <Superscript>18</Superscript>F-FDG PET/CT Parameters for Detection of Lymph Node Metastasis in Cutaneous Melanoma

Purpose

The purpose of this study was to investigate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) parameters in the detection of regional lymph node (LN) metastasis in patients with cutaneous melanoma.

Methods

We evaluated patients with cutaneous melanoma who underwent FDG PET/CT for initial staging or recurrence evaluation. A total of 103 patients were enrolled, and 165 LNs were evaluated. LNs that were confirmed pathologically or by follow-up imaging were included in this study. PET parameters, including maximum standardized uptake value (SUVmax), total lesion glycolysis and tumour-to-liver ratio, were used to determine the presence of metastases, and the results were compared with CT-determined LN metastasis. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off values of the FDG PET parameters.

Results

A total of 93 LNs were malignant, and 84 LNs were smaller than 10 mm. In all 165 LNs, an SUVmax of >2.51 showed a sensitivity of 73.1%, a specificity of 88.9%, and an accuracy of 80.0% in detecting metastatic LNs. CT showed a higher specificity (87.3%) and lower accuracy (65.5%). For non-enlarged regional LNs (<10 mm), an SUVmax cut-off value of 1.4 showed the highest negative predictive value (81.3%). For enlarged LNs (≥10 mm), an SUVmax cut-off value of 2.4 showed the highest sensitivity (90.7%) and accuracy (88.9%) in detecting metastatic LNs.

Conclusions

In patients with cutaneous melanoma, an SUVmax of >2.4 showed a high sensitivity (91%) and accuracy (89%) in detecting metastasis in LNs ≥1 cm, and LNs <1 cm with an SUVmax <1.4 were likely to be benign.

     

Visual and statistical analysis of <Superscript>18</Superscript>F-FDG PET in primary progressive aphasia

Purpose

Diagnosing progressive primary aphasia (PPA) and its variants is of great clinical importance, and fluorodeoxyglucose (FDG) positron emission tomography (PET) may be a useful diagnostic technique. The purpose of this study was to evaluate interobserver variability in the interpretation of FDG PET images in PPA as well as the diagnostic sensitivity and specificity of the technique. We also aimed to compare visual and statistical analyses of these images.

Methods

There were 10 raters who analysed 44 FDG PET scans from 33 PPA patients and 11 controls. Five raters analysed the images visually, while the other five used maps created using Statistical Parametric Mapping software. Two spatial normalization procedures were performed: global mean normalization and cerebellar normalization. Clinical diagnosis was considered the gold standard.

Results

Inter-rater concordance was moderate for visual analysis (Fleiss’ kappa 0.568) and substantial for statistical analysis (kappa 0.756–0.881). Agreement was good for all three variants of PPA except for the nonfluent/agrammatic variant studied with visual analysis. The sensitivity and specificity of each rater’s diagnosis of PPA was high, averaging 87.8 and 89.9 % for visual analysis and 96.9 and 90.9 % for statistical analysis using global mean normalization, respectively. In cerebellar normalization, sensitivity was 88.9 % and specificity 100 %.

Conclusion

FDG PET demonstrated high diagnostic accuracy for the diagnosis of PPA and its variants. Inter-rater concordance was higher for statistical analysis, especially for the nonfluent/agrammatic variant. These data support the use of FDG PET to evaluate patients with PPA and show that statistical analysis methods are particularly useful for identifying the nonfluent/agrammatic variant of PPA.

     

<Superscript>18</Superscript>F-FDG uptake by rectal cancer is similar in mucinous and nonmucinous histological subtypes

Purpose

PET/CT has been considered limited for the evaluation of mucinous colorectal tumors due to low ¹⁸F-FDG uptake. The aim of our study was to compare PET/CT variables in mucinous (MC) and nonmucinous (NMC) rectal adenocarcinomas.

Methods

Consecutive patients with cT2-4N0-2M0 rectal cancer included in a prospective clinical trial were reviewed. PET/CT was performed for primary baseline staging. Visual and quantitative analysis included SUVmax and SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG). PET/CT parameters were compared according to histological subtypes.

Results

Overall, 73 patients were included (18 mucinous and 55 nonmucinous). SUVmax values were similar between MC and NMC (19.7 vs. 16.6; p = 0.5). MTV and TLG values were greater in the MC group (103.9 vs. 54.1; p = 0.007 and 892.5 vs. 358.8; p = 0.020) due to larger tumor volumes of MC.

Conclusions

Metabolic parameters at baseline PET/CT for patients with rectal cancer are similar in mucinous and nonmucinous histological subtypes.

     

<Superscript>18</Superscript>F-FDG PET/CT imaging factors that predict ischaemic stroke in cancer patients

Purpose

¹⁸F-FDG PET/CT can acquire both anatomical and functional images in a single session. We investigated which factors of ¹⁸F-FDG PET/CT imaging have potential as biomarkers for an increased risk of ischaemic stroke in cancer patients.

Methods

From among cancer patients presenting with various neurological symptoms and hemiparesis, 134 were selected as eligible for this retrospective analysis. A new infarct lesion on brain MRI within 1 year of FDG PET/CT defined future ischaemic stroke. The target-to-background ratio (TBR) of each arterial segment was used to define arterial inflammation on PET imaging. Abdominal obesity was defined in terms of the area and proportion of visceral adipose tissue (VAT), subcutaneous adipose tissue and total adipose tissue (TAT) on a single CT slice at the umbilical level.

Results

Ischaemic stroke confirmed by MRI occurred in 30 patients. Patients with stroke had higher TBRs in the carotid arteries and abdominal aorta (P?<?0.001) and a higher VAT proportion (P?=?0.021) and TAT proportion (P?=?0.041) than patients without stroke. Multiple logistic regression analysis showed that TBRs of the carotid arteries and abdominal aorta, VAT and TAT proportions, and the presence of a metabolically active tumour were significantly associated with future ischaemic stroke. Combining PET and CT variables improved the power for predicting future ischaemic stroke.

Conclusion

Our findings suggest that arterial FDG uptake and hypermetabolic malignancy on PET and the VAT proportion on CT could be independent predictors of future ischaemic stroke in patients with cancer and could identify those patients who would benefit from medical treatment.

     

[<Superscript>18</Superscript>F]FDG PET accurately differentiates infected and non-infected non-unions after fracture fixation

Purpose

Complete fracture healing is crucial for good patient outcomes. A major complication in the treatment of fractures is non-union. The pathogenesis of non-unions is not always clear, although implant-associated infections play a significant role, especially after surgical treatment of open fractures. We aimed to evaluate the value of [¹⁸F]FDG PET in suspected infections of non-union fractures.

Methods

We retrospectively evaluated 35 consecutive patients seen between 2000 and 2015 with suspected infection of non-union fractures, treated at a level I trauma center. The patients underwent either [¹⁸F]FDG PET/CT (N?=?24), [¹⁸F]FDG PET (N?=?11) plus additional CT (N?=?8), or conventional X-ray (N?=?3). Imaging findings were correlated with final diagnosis based on intraoperative culture or follow-up.

Results

In 13 of 35 patients (37 %), infection was proven by either positive intraoperative tissue culture (N?=?12) or positive follow-up (N?=?1). [¹⁸F]FDG PET revealed 11 true-positive, 19 true-negative, three false-positive, and two false-negative results, indicating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 85 %, 86 %, 79 %, 90 %, and 86 %, respectively. The SUV_max was 6.4?±?2.7 in the clinically infected group and 3.0?±?1.7 in the clinically non-infected group (p <0.01). The SUV_ratio was 5.3?±?3.3 in the clinically infected group and 2.6?±?1.5 in the clinically non-infected group (p <0.01).

Conclusion

[¹⁸F]FDG PET differentiates infected from non-infected non-unions with high accuracy in patients with suspected infections of non-union fractures, for whom other clinical findings were inconclusive for a local infection. [¹⁸F]FDG PET should be considered for therapeutic management of non-unions.

     

<Superscript>18</Superscript>F-FDG and <Superscript>18</Superscript>F-FLT PET/CT imaging in the characterization of mediastinal lymph nodes

Purpose

There is currently no single modality for accurate characterization of enlarged mediastinal lymph nodes into benign or malignant. Recently ¹⁸F-fluorothymidine (FLT) has been used as a proliferation marker. In this prospective study, we examined the role of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and ¹⁸F-FLT PET/CT in categorizing mediastinal lymph nodes as benign or malignant.

Materials and methods

A total of 70 consecutive patients with mediastinal lymphadenopathy detected on computed tomography (CT) or chest radiograph underwent whole body ¹⁸F-FLT PET/CT and ¹⁸F-FDG PET/CT (within 1 week of each other). Lymph nodal tracer uptake was determined by calculation of standardized uptake value (SUV) with both the tracers. Results of PET/CT were compared with histopathology of the lymph nodes.

Results

Histopathology results showed thirty-seven patients with sarcoidosis, seven patients with tuberculosis, nine patients with non-small cell lung cancer, five patients with Hodgkin’s lymphoma and twelve patients with non-Hodgkin’s lymphoma. The mean FDG SUV_max of sarcoidosis, tuberculosis, Hodgkin’s and non-Hodgkin’s lymphoma was 12.7, 13.4, 8.2, and 8.8, respectively, and the mean FLT SUV_max was 6.0, 5.4, 4.4, and 3.8, respectively. It was not possible to characterize mediastinal lymphadenopathy as benign or malignant solely based on FDG SUV_max values (p > 0.05) or FLT SUV_max values (p > 0.05). There was no significant difference in FDG uptake (p > 0.9) or FLT uptake (p > 0.9) between sarcoidosis and tuberculosis. In lung cancer patients, the FDG SUV_max and FLT SUV_max of those lymph nodes with tumor infiltration on biopsy was 6.7 and 3.9, respectively, and those without nodal infiltration was 6.4 and 3.7, respectively, and both the tracers were not able to characterize the nodal status as malignant or benign (p > 0.05).

Conclusion

Though ¹⁸F-FLT PET/CT and ¹⁸F-FDG PET/CT reflect different aspects of biology, i.e., proliferation and metabolism, respectively, neither tracer could provide satisfactory categorization of benign and malignant lymph nodes. The results of this study clearly suggest that differentiation of mediastinal nodes into benign and malignant solely based on SUV_max values cannot be relied upon, especially in settings where tuberculosis and sarcoidosis are common.

     

<Superscript>11</Superscript>C-methylaminoisobutyric acid (MeAIB) PET for evaluation of prostate cancer: compared with <Superscript>18</Superscript>F-fluorodeoxyglucose PET

Objective

α-N-methyl-¹¹C-methylaminoisobutyric acid (¹¹C-MeAIB) is a selective substrate of system A amino acid transport, and known to accumulate in malignant lesions. The aim of this study was to evaluate the utility of MeAIB PET for the assessment of prostate cancer, compared with FDG PET.

Methods

Thirty-four men (age range 57–77 years) with prostate cancer were prospectively enrolled, and underwent MeAIB PET and FDG PET between January 2011 and January 2013. MeAIB PET and FDG PET were performed at 20 and 50 min post-injection, respectively. SUVmax of the prostate was calculated, and visual analysis was conducted for MeAIB and FDG PET studies. MRI images were visually evaluated if available. All patients received total prostatectomy subsequently, and imaging findings were compared with pathological results, including T stage, Gleason score, and tumor size. The patient-based and lesion-based sensitivity and specificity were calculated according to pathological significant cancer.

Results

Mean value of SUVmax of ¹¹C-MeAIB PET and ¹⁸F-FDG PET in prostate cancer were 3.18 (±1.90, range; 1.55–9.57) and 3.88 (±2.85, range; 2.04–14.47). MeAIB PET and FDG PET were positive by visual analysis in 47.1 % (16/34) and 44.1 % (15/34) of the patients. MRI was positive in 51.5 % (17/33). Pathological stage and Gleason score were as follows: Stage 2 (n = 23), 3 (n = 8), and 4 (n = 3); Gleason score 6 (n = 13), 7 (n = 16), 8 (n = 3), and 9 (n = 2). The sensitivities tended to be higher according to higher pathological T stage or Gleason sum score for both MeAIB and FDG PET studies. Visual analysis of both MeAIB PET and FDG PET had significant correlation with extraprostatic extension (p < 0.05). MeAIB PET and FDG PET had complementary results by visual analysis in the assessment of prostate cancer. The patient-based sensitivity of MeAIB PET, FDG PET, and MRI were 51.6, 48.4, and 56.7 %, respectively. The patient-based specificity of these modalities was 100 % for each modality.

Conclusions

MeAIB PET has better diagnostic results than FDG PET for the assessment of significant prostate cancer, and these PET studies showed complementary results. MRI has even better diagnostic results than ¹¹C-MeAIB PET. MeAIB accumulates in prostate cancer, which indicates that the system A amino acid transport pathway is activated in prostate cancer.

     

Assessing the role of <Superscript>18</Superscript>F-FDG PET and <Superscript>18</Superscript>F-FDG PET/CT in the diagnosis of soft tissue musculoskeletal malignancies: a systematic review and meta-analysis

Purpose

Twelve years ago a meta-analysis evaluated the diagnostic performance of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in assessing musculoskeletal soft tissue lesions (MsSTL). Currently, PET/CT has substituted PET imaging; however, there has not been any published meta-analysis on the use of PET/CT or a comparison of PET/CT with PET in the diagnosis of MsSTL. Therefore, we conducted a meta-analysis to identify the current diagnostic performance of ¹⁸F-FDG PET/CT and determine if there is added value when compared to PET.

Methods

A systematic review of English articles was conducted, and MEDLINE PubMed, the Cochrane Library, and Embase were searched from 1996 to March 2015. Studies exploring the diagnostic accuracy of ¹⁸F-FDG PET/CT (or dedicated PET) compared to histopathology in patients with MsSTL undergoing investigation for malignancy were included.

Results

Our meta-analysis included 14 articles composed of 755 patients with 757 soft tissue lesions. There were 451 (60 %) malignant tumors and 306 benign lesions. The ¹⁸F-FDG PET/CT (and dedicated PET) mean sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for diagnosing MsSTL were 0.96 (0.90, 1.00), 0.77 (0.67, 0.86), 0.88 (0.85, 0.91), 0.86 (0.78, 0.94), and 0.91 (0.83, 0.99), respectively. The posterior mean (95 % highest posterior density interval) for the AUC was 0.92 (0.88, 0.96). PET/CT had higher specificity, accuracy, and positive predictive value when compared to a dedicated PET (0.85, 0.89, and 0.91 vs 0.71, 0.85, and 0.82, respectively).

Conclusion

¹⁸F-FDG PET/CT and dedicated PET are both highly accurate in the diagnosis of MsSTL. PET/CT is more accurate and specific and has a higher positive predictive value than PET.

     

<Superscript>68</Superscript>Ga-PSMA-HBED-CC PET imaging in breast carcinoma patients

Background

To report on imaging findings using ⁶⁸Ga-PSMA-HBED-CC PET in a series of 19 breast carcinoma patients.

Methods

⁶⁸Ga-PSMA-HBED-CC PET imaging results obtained were compared to routinely performed staging examinations and analyzed as to lesion location and progesterone receptor status.

Results

Out of 81 tumor lesions identified, 84% were identified on ⁶⁸Ga-PSMA-HBED-CC PET. ⁶⁸Ga-PSMA-HBED-CC SUVmean values of distant metastases proved significantly higher (mean, 6.86, SD, 5.68) when compared to those of primary or local recurrences (mean, 2.45, SD, 2.55, p?=?0.04) or involved lymph nodes (mean, 3.18, SD, 1.79, p?=?0.011). SUVmean values of progesterone receptor-positive lesions proved not significantly different from progesterone receptor-negative lesions. SUV values derived from FDG PET/CT, available in seven patients, and ⁶⁸Ga-PSMA-HBED-CC PET/CT imaging proved weakly correlated (r?=?0.407, p?=?0.015).

Conclusions

⁶⁸Ga-PSMA-HBED-CC PET/CT imaging in breast carcinoma confirms the reported considerable variation of PSMA expression on human solid tumors using immunohistochemistry.

     

Effect of <Superscript>18</Superscript>F-fluorodeoxyglucose extravasation on time taken for tumoral uptake to reach a plateau: animal and clinical PET analyses

Objective

The present study aimed to investigate the effect of ¹⁸F-fluorodeoxyglucose (FDG) extravasation on the time taken for tumoral uptake to reach a plateau.

Methods

For the animal experiment, FDG extravasation was conducted in the tails of HCT116 tumor-bearing xenograft mice models in three groups (no extravasation, 40 % extravasation, and 80 % extravasation; n = 5, each). Dynamic positron emission tomography (PET) images were acquired over a period of 2 h following injection. Time–activity curves for FDG in the tails and tumors were calculated. For the clinical experiment, 22 patients (male:female, 14:8; age range, 70.8 ± 9.2 years) were subjected to PET/computed tomography (PET/CT) 1 h after the injection of FDG. The inclusion criteria were as follows: (1) submitted to both whole-body and subsequent regional scanning; (2) entire extravasation activity visualized in the whole-body images; (3) tumor visualized on both whole-body and additional regional images; and (4) status of tumor either confirmed by biopsy or clinically suspected for malignancy. The standardized uptake values (SUVs) of the tumors (on the whole-body and additional PET images) and extravasation sites were recorded.

Results

There were no significant differences in the time taken for tumoral uptake to reach a plateau and that to reach minimum activity at the extravasation site among the three groups of mice. However, the mean tumoral activity and activity at the extravasation site were negatively correlated at 1 h post-injection. According to the clinical PET findings, the differences in SUV between the whole-body and regional images were not significantly correlated with the interval between injection of FDG and start of whole-body scanning, interval between the start of whole-body scanning and start of regional scanning, extravasation volume, maximum SUV of the extravasation site, or total activity at the extravasation site.

Conclusions

The time taken for tumoral uptake to reach a plateau is not affected by extravasation, even at extensive degrees. Thus, in routine practice, the imaging time of approximately 60 min post-injection need not be modified even if extravasation is identified. However, tumor SUV may be underestimated in cases of extravasation.

     

Long-term follow-up and role of FDG PET in advanced pancreatic neuroendocrine patients treated with <Superscript>177</Superscript>Lu-D OTATATE

Purpose

Lu-DOTATATE (Lu-PRRT) is a valid therapeutic option in differentiated pancreatic neuroendocrine tumors (P-NETs). FDG PET seems to be an important prognostic factor in P-NETs. We evaluated the efficacy of Lu-PRRT and the role of FDG PET in 60 patients with advanced P-NETs.

Methods

From March 2008 to June 2011, 60 consecutive patients with P-NETs were enrolled in the study. Follow-up lasted until March 2016. Eligible patients were treated with two different total cumulative activities (18.5 or 27.8 GBq in 5 cycles every 6–8 weeks), according to kidney and bone marrow parameters.

Results

Twenty-eight patients received a mean full activity (FA) of 25.9 GBq and 32 a mean reduced activity (RA) of 18.5 GBq. The disease control rate (DCR), defined as the sum of CR+PR+SD was 85.7 % in the FA group and 78.1 % in the RA group. Median progression-free survival (mPFS) was 53.4 months in the FA group and 21.7 months in the RA group (P?=?0.353). Median overall survival (mOS) was not reached (nr) in FA patients and was 63.8 months in the RA group (P?=?0.007). Fifty-five patients underwent an FDG PET scan before Lu-PRRT, 32 (58 %) showing an increased FDG uptake in tumor sites. mPFS was 21.1 months in FDG PET-positive patients and 68.7 months in the FDG PET-negative group (P?<?0.0002), regardless of the total activity administered.

Conclusion

Both FA and RA are active in patients undergoing Lu-PRRT. However, an FA of 27.8 GBq of Lu-PRRT prolongs PFS and OS compared to an RA of 18.5 GBq. Our results indicate that FDG PET is an independent prognostic factor in this patient setting.

     

The utility of PET/CT with <Superscript>68</Superscript>Ga-DOTATOC in sarcoidosis: comparison with <Superscript>67</Superscript>Ga-scintigraphy

Objective

This study was designed to compare the clinical efficacy of ⁶⁸Ga-DOTA-Tyr-octreotide (DOTATOC)-positron emission tomography (PET)/computed tomography (CT) with that of conventional ⁶⁷Ga-scintigraphy (GS), and to correlate quantitative parameters on DOTATOC-PET/CT with clinical data, in patients with sarcoidosis.

Methods

Twenty patients who were histologically and/or clinically diagnosed with sarcoidosis and underwent both DOTATOC-PET/CT and GS were analyzed in this study. The numbers of patients with positive findings for each organ were determined. The total numbers of involved nodal areas in the chest, as determined by DOTATOC-PET and gallium single-photon emission tomography (Ga-SPECT), were compared. The correlations between quantitative parameters on PET and clinical laboratory data were evaluated.

Results

DOTATOC-PET/CT was positive in 19 patients, being negative in only one patient with chronic inactive sarcoidosis, whereas GS was positive in 17 patients. DOTATOC-PET/CT visualized more lesions in lymph nodes, uvea, and muscles than did Ga-scintigraphy and identified more involved areas than did GS-SPECT (p < 0.0001). Whole-body active lesion volume showed a significant, but moderate correlation with angiotensin-converting enzyme level (ρ = 0.64, p = 0.0044).

Conclusions

PET/CT with DOTATOC may be superior to conventional GS in detecting sarcoidosis lesions, especially in lymph nodes, uvea, and muscles. Volumetric parameters in DOTATOC-PET/CT may be helpful in estimating the activity of sarcoidosis.

     

<Superscript>68</Superscript>Ga-PSMA-11 dynamic PET/CT imaging in biochemical relapse of prostate cancer

Objectives

We aim to investigate the pharmacokinetics and distribution of the recently clinically introduced radioligand ⁶⁸Ga-PSMA-11 in men with recurrent prostate cancer (PC) by means of dynamic and whole-body PET/CT. The correlation between PSA levels and ⁶⁸Ga-PSMA-11 PET parameters is also investigated.

Methods

31 patients with biochemical failure after primary PC treatment with curative intent (median age 71.0 years) were enrolled in the analysis. The median PSA value was 2.0 ng/mL (range?=?0.1 – 130.0 ng/mL) and the median Gleason score was 7 (range?=?5 – 9). 8/31 (25.8 %) of the included patients had a PSA value?<?0.5 ng/ml. All patients underwent dynamic PET/CT (dPET/CT) scanning (60 min) of the pelvis and lower abdomen as well as whole-body PET/CT with ⁶⁸Ga-PSMA-11. dPET/CT assessment was based on qualitative evaluation, SUV calculation, and quantitative analysis based on a two-tissue compartment model and a non-compartmental approach leading to the extraction of fractal dimension (FD).

Results

22/31 patients (71.0 %) were ⁶⁸Ga-PSMA-11-positive, while 9/31 (29.0 %) patients were ⁶⁸Ga-PSMA-11-negative. The median PSA value in the ⁶⁸Ga-PSMA-11-positive group was significantly higher (median?=?2.35 ng/mL; range?=?0.19 – 130.0 ng/mL) than in the ⁶⁸Ga-PSMA-11-negative group (median value: 0.34 ng/mL; range?=?0.10 – 4.20 ng/mL). A total of 76 lesions were semi-quantitatively evaluated. PC recurrence-associated lesions demonstrated a mean SUV_average?=?12.4 (median?=?9.0; range?=?2.2 – 84.5) and mean SUV_max = 18.8 (median?=?14.1; range?=?3.1 – 120.3). Dynamic PET/CT studies of the pelvis revealed the following mean values for the PC recurrence-suspicious lesions: K₁?=?0.26, k₃?=?0.30, influx?=?0.14 and FD?=?1.24. Time–activity curves derived from PC-recurrence indicative lesions revealed an increasing ⁶⁸Ga-PSMA-11 accumulation during dynamic PET acquisition. Correlation analysis revealed a moderate, but significant, correlation between PSA levels and the number of lesions detected on ⁶⁸Ga-PSMA-11 PET/CT (r?=?0.54) and between PSA levels and SUV_average (r?=?0.48) or SUV_max (r?=?0.44).

Conclusions

Ga-PSMA-11 PET/CT demonstrated an overall detection rate of 71.0 % 60 min p.i. of the radiotracer in a mixed patient population with respect to PSA levels and including patients with very low PSA values. Higher PSA values were associated with a higher detection rate. The tracer uptake in PC-recurrence-indicative lesions is increasing during the 60 minutes of dynamic PET acquisition.

     

Recurrent prostate cancer detection with <Emphasis Type="Italic">anti</Emphasis>-3-[<Superscript>18</Superscript>F]FACBC PET/CT: comparison with CT

Purpose

To compare the diagnostic performance of the synthetic amino acid analogue PET radiotracer anti-3-[¹⁸F]FACBC (fluciclovine) with that of CT in the detection of recurrent prostate carcinoma.

Methods

This was a retrospective analysis of 53 bone scan-negative patients with suspected recurrent prostate carcinoma who underwent fluciclovine PET/CT and routine clinical CT within 90 days of each other. The correlation between imaging findings and histology and clinical follow-up was evaluated. Positivity rates and diagnostic performance were calculated for fluciclovine PET/CT and CT.

Results

Of 53 fluciclovine PET/CT and 53 CT examinations, 41 (77.4 %) and 10 (18.9 %), respectively, had positive findings for recurrent disease. Positivity rates were higher with fluciclovine PET/CT than with CT at all prostate-specific antigen (PSA) levels, PSA doubling times and original Gleason scores. In the prostate/bed, fluciclovine PET/CT was true-positive in 31 and CT was true-positive in 4 of 51 patients who met the reference standard. In extraprostatic regions, fluciclovine PET/CT was true-positive in 12 and CT was true-positive in 3 of 41 patients who met the reference standard. Of the 43 index lesions used to prove positivity, 42 (97.7 %) had histological proof. In 51 patients with sufficient follow-up to calculate diagnostic performance in the prostate/bed, fluciclovine PET/CT demonstrated a sensitivity of 88.6 %, a specificity of 56.3 %, an accuracy of 78.4 %, a positive predictive value (PPV) of 81.6 %, and a negative predictive value (NPV) of 69.2 %; the respective values for CT were 11.4 %, 87.5 %, 35.3 %, 66.7 % and 31.1 %. In 41 patients with sufficient follow-up to calculate diagnostic performance in extraprostatic regions, fluciclovine PET/CT demonstrated a sensitivity of 46.2 %, a specificity of 100 %, an accuracy of 65.9 %, a PPV of 100 %, and an NPV of 51.7 %; the respective values for CT were 11.5 %, 100 %, 43.9 %, 100 % and 39.5 %.

Conclusion

The diagnostic performance of fluciclovine PET/CT in recurrent prostate cancer is superior to that of CT and fluciclovine PET/CT provides better delineation of prostatic from extraprostatic recurrence.