Comparison of 18F-FDG PET/MR and PET/CT for pretreatment TNM staging of hilar cholangiocarcinoma.

PURPOSE: 18F-FDG PET/MR has been applied to the diagnosis and preoperative staging in various tumor types; however, reports using PET/MR in hilar cholangiocarcinoma (HCCA) are rare. We investigated the value of PET/MR for preoperative staging and compared it with PET/CT in HCCA. METHODS: Fifty-eight patients with HCCA confirmed by pathology were retrospectively analyzed. 18F-FDG PET/CT imaging was performed first, followed with whole-body PET/MR imaging. SUVmax of tumor and normal liver tissue were measured. Paired T test was used to compare SUVmax of tumor and normal liver tissue of PET/CT and PET/MR. In addition, McNemar test was used to compare the accuracy of TNM staging and Bismuth-Corlette typing between PET/CT and PET/MR. RESULTS: There was no significant difference in SUVmax between PET/CT and PET/MR in primary tumor lesions (6.6 ± 5.5 vs. 6.8 ± 6.2, P = 0.439). SUVmax of PET/CT and PET/MR in normal liver parenchyma was significantly different (3.0 ± 0.5 vs. 2.1 ± 0.5, P < 0.001). The accuracy of PET/MR in diagnosing T staging and N staging was significantly higher than those of PET/CT (72.4% vs. 58.6%, P = 0.022 and 84.5% vs. 67.2%, P = 0.002). There was no significant difference between PET/CT and PET/MR in M staging (94.8% vs. 98.3%, P = 0.5). The classification accuracy of PET/MR in Bismuth-Corlette was significantly higher than that of PET/CT (89.7% vs. 79.3%), P = 0.031. CONCLUSIONS: The diagnostic accuracy of 18F-FDG PET/MR was superior to that of PET/CT in preoperative T staging, N staging, and Bismuth-Corlette classification of HCCA. In M staging, the diagnostic accuracy of PET/MR was similar to that of PET/CT.

Dynamic perfusion SPECT for functional evaluation in symptomatic patients with myocardial bridging.

BACKGROUND: The aim of this study was to investigate the feasibility and diagnostic value of myocardial flow reserve (MFR) assessed by rest/stress myocardial perfusion imaging with dynamic single-photon emission computed tomography (SPECT) in the functional evaluation of myocardial bridge (MB). METHODS: From May 2017 to July 2021, patients with angiographically confirmed isolated MB on the left anterior descending artery (LAD) who underwent dynamic SPECT myocardial perfusion imaging were retrospectively included. The assessment of semiquantitative indices of myocardial perfusion (summed stress scores, SSS) and quantitative parameters (MFR) was performed. RESULTS: A total of 49 patients were enrolled. The mean age of the subjects was 61.0 ± 9.0 years. All of the patients were symptomatic, and 16 cases (32.7%) presented with typical angina. SPECT-derived MFR showed a borderline significantly negative correlation with SSS (r = 0.261, P = .070). There was a trend of higher prevalence of impaired myocardial perfusion defined as MFR < 2 than as SSS ≥ 4 (42.9% vs 26.5%; P = .090). CONCLUSION: Our data support that SPECT MFR may be a useful parameter for the functional assessment of MB. In patients with MB, the use of dynamic SPECT could be a potential method for hemodynamic assessment.

Myocardial injury is a risk factor for 6-week mortality in liver cirrhosis associated esophagogastric variceal bleeding.

This study sought to investigate risk factors for 6-week mortality of patients with decompensated liver cirrhosis associated esophagogastric variceal bleeding (EGVB) and clinical characteristics of myocardial injury in cirrhotic patients with EGVB. This retrospective cohort study included 249 patients with decompensated liver cirrhosis associated EGVB in the Department of Emergency. Patients were divided into two groups including liver cirrhosis associated EGVB without myocardial injury and liver cirrhosis associated EGVB with myocardial injury. Myocardial injury, recurrent bleeding, total bilirubin (TBIL) level and dyslipidemia are independent risk factors for 6-week mortality in liver cirrhosis associated EGVB. Among all patients with liver cirrhosis associated EGVB, 90 (36.2%) had myocardial injury and 159 individuals (63.8%) not. The 6-week mortality in the group with myocardial injury was 21%, which was significantly higher than that of 7% in the group without myocardial injury. More patients in the myocardial injury group smoked, had moderate to severe esophageal varices, liver failure, and Child-Pugh C liver function compared to the non-myocardial injury group. Myocardial injury, recurrent bleeding, TBIL level and dyslipidemia are independent risk factors for death within 6 weeks in liver cirrhosis associated EGVB. The 6-week mortality is considerably higher in patients with myocardial injury in liver cirrhosis associated EGVB than those without myocardial injury.

Smart down/upconversion nanomachines integrated with "AND" logic computation and enzyme-free amplification for NIR-II fluorescence-assisted precise and enhanced photodynamic therapy.

Upconversion nanoparticles enable indirect activation of photodynamic therapy (PDT) using near-infrared (NIR) light, providing an excellent alternative for treating deep tumors. However, conventional NIR light-triggered PDT systems suffered from low spatiotemporal accuracy and restricted therapeutic efficiency in vivo. In this work, DNA logic circuits were functionally modified on down/upconversion nanoparticles (D/UCNPs) to construct smart down/upconversion nanomachines (D/UCNMs) for NIR light-triggered PDT toward target tumors. Upon dual inputs of tumor-associated GSH and TK1 mRNA, DNA logic circuits perform "AND" logic computation and initiate the toehold-mediated strand displacement reaction. Meanwhile, the quenched upconversion fluorescence was recovered and then the approaching photosensitizers were activated, leading to in situ output of singlet oxygen (1O2) for precise and enhanced PDT. Importantly, the biodistribution of the D/UCNMs in vivo could be visualized by second near-infrared (NIR-II) fluorescence imaging via the downconversion luminance of D/UCNPs, which further contributed to performing precise PDT. This work provides new insights into the development of precise and highly efficient PDT systems.

Correlation among maximum standardized 18F-FDG uptake and pathological differentiation, tumor size, and Ki67 in patients with moderately and poorly differentiated intrahepatic cholangiocarcinoma.

OBJECTIVE: To investigate the correlation among the maximum standardized uptake value (SUVmax) on fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) and tumor differentiation, size, and Ki67 in patients with moderately and poorly differentiate dintrahepatic cholangiocarcinoma (ICC). MATERIALS AND METHODS: The 18F-FDG PET/CT imaging data of 116 patients with single ICC lesions confirmed by pathology were retrospectively evaluated. Pathological characteristics of the tumor such as the largest tumor diameter, differentiation, Ki67 expression, SUVmax of the primary tumor, and the tumor to normal background ratio (TNR) were recorded. RESULTS: Among the 116 lesions, 45, 51, and 20 lesions were classified into the moderately differentiated, moderately-poorly, and poorly differentiated groups, respectively. There were significant differences in the SUVmax (P=0.033) and TNR (P=0.044) among the three groups. Maximum SUV was significantly correlated with differentiation (r=0.244, P=0.008). When the cases were categorized according to the tumor size (group 1, ≤3cm, n=14; group 2, >3 and ≤5 cm, n=37; group 3, >5 and ≤10 cm, n=52; group 4, >10 cm, n=13), there were significant differences in the SUVmax (P<0.001) and TNR (P<0.001) among the four groups. Maximum SUV was significantly correlated with tumor size (r=0.481, P<0.001). Among the 116 lesions, 38 lesions and 78 lesions were classified into the low Ki67 and high Ki67 expression groups, respectively. There were significant differences in the SUVmax (P=0.028) and TNR (P=0.007) between the two groups. Maximum SUV was significantly correlated with Ki67 expression (r=0.242, P=0.009). CONCLUSION: In moderately and poorly differentiated ICC, the SUVmax and TNR are significantly associated with tumor differentiation, size, and Ki67 expression.

Functional significance of intermediate coronary stenosis in patients with single-vessel coronary artery disease: A comparison of dynamic SPECT coronary flow reserve with intracoronary pressure-derived fractional flow reserve (FFR).

BACKGROUND: The aim of this study was to investigate the correlation of coronary flow reserve (CFR) assessed by rest/stress myocardial perfusion imaging with dynamic single-photon emission computed tomography (SPECT) with intracoronary pressure-derived fractional flow reserve (FFR) in patients with single-vessel coronary artery disease (CAD). METHODS: Patients with suspected or known stable CAD who were referred for invasive coronary angiography were prospectively enrolled. Both invasive FFR and SPECT were performed in subjects with single-vessel intermediate coronary stenosis. A cutoff value of < 0.8 was used to define abnormal FFR. RESULTS: A total of 34 patients were enrolled. The mean age of the subjects was 62.1 ± 6.7 years, and 79.4% were male. SPECT-derived CFR showed a significantly moderate correlation with FFR (r = 0.505, P = .003). The diagnostic performance for the identification of abnormal FFR in terms of sensitivity, specificity, and accuracy was 88.9%, 83.3%, and 87.9%, respectively, for CFR, with an optimized cutoff value of 1.73. CONCLUSION: In patients with single-vessel CAD, SPECT CFR was useful for the detection of functionally significant stenosis. Our data support the use of this technique as an optional method for hemodynamic assessment, especially when FFR results are in normal range.

Reversible assembly-disassembly of plasmonic spherical nucleic acids enabling temperature-self-controllable and biomarker-activatable photothermal effects.

Since the photothermal heating of plasmonic spherical nucleic acids (pSNAs) depends on the self-assembly level and melting temperature (Tm), a temperature-self-controllable and biomarker-activatable photothermal effect in vivo was thus achieved using the Tm-dependent assembly-disassembly of pSNAs.

Role of dual-time point 18F-FDG PET/CT imaging in the primary diagnosis and staging of hilar cholangiocarcinoma.

PURPOSE: The aim of this study was to evaluate the role of dual-time point 18F-FDG PET/CT imaging in the primary diagnosis and staging of hilar cholangiocarcinoma (HCCA). METHODS: Dual-time point FDG PET/CT findings, including early phase whole-body scanning and abdominal delayed phased performed 1 and 2 h after radiotracer injection, respectively, were retrospective reviewed in 69 patients conformed HCCA by histology. PET/CT was evaluated based on visual interpretation and the semiquantitative index of SUVmax and tumor-to-normal liver tissue ratio (TNR) for both early and delayed images. RESULTS: For all 69 HCCA patients, the mean SUVmax of the lesion and TNR in delayed phase was significantly higher than that in early phase (6.1 ± 4.7, 2.2 ± 1.7, vs 5.1 ± 3.4, 1.6 ± 1.1; P < 0.001). The sensitivity and accuracy value of detection primary lesions was 69.6% and 70% in early phase vs 76.8% and 76.8% in delay phase, respectively. There was a significant correlation between lesion SUVmax and Ki67 index in both dual-time imaging (r = 0.462, P < 0.001 in early phase vs r = 0.47, P < 0.001 in delay phase). The sensitivity, specificity and accuracy value of metastatic lymph nodes prediction was 50%, 67.3% and 71% in early phase vs 62.5%, 73.3% and 76.8% in delayed phase, respectively. The sensitivity, specificity and accuracy of FDG PET/CT in detecting distant metastasis in our study was 75%, 100% and 97.1%. There was no difference of predicting distant metastasis between early phase and delayed phase. CONCLUSION: Delayed phase in dual-time point 18F-FDG PET/CT scan provides additional usefulness for detection primary tumor and lymph nodes metastases in HCCA, but there was no added benefit of delayed PET/CT imaging in detection of distant metastases in this study. SUVmax in early and delayed phase could be used to assess tumor aggressiveness in pre-treatment HCCA.

Imaging characteristics and prognostic values of hepatic epithelioid hemangioendothelioma on 18F-FDG PET/CT.

Hepatic epithelioid hemangioendothelioma (HEHE) is a low-to-intermediate-grade malignant mesenchymal tumor. The diagnostic and prognostic values of 2-[18F] fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) to patients with HEHE have not been fully validated. Patient survival outcomes (including overall survival [OS] and progression-free survival [PFS]), lesions characteristics and semi-quantitative parameters, in terms of maximum standardized uptake value (SUVmax), peak SUV (SUVpeak), total lesion glycolysis (TLG) and metabolic tumor volume (MTV) on 18F-FDG PET/CT of 20 cases with HEHE were measured and analyzed. A total of 310 liver lesions were detected (excluding the diffuse-type lesions in 3 cases). Most lesions had higher SUVmax in delayed imaging than in early imaging (P = 0.013). Patients with multiple organs involved had higher death rate (P = 0.022), higher progression rate (P = 0.020), shorter OS (P = 0.011), larger lesion SUVmax (P = 0.048) and TLG (P = 0.033) than those with only liver involved. The area under curves (AUCs) from the receiver operating characteristic (ROC) curve analysis were 0.960, 0.949, 0.980 and 0.960 for SUVmax, SUVpeak, TLG and MTV, respectively, in predicting OS (P = 0.005, 0.008, 0.001 and 0.024, respectively). For predicting PFS, the AUCs were 0.791, 0.824, 0.857 and 0.813 (P = 0.036, 0.019, 0.010 and 0.024), respectively. Dual-time-point imaging may improve lesions detectability. Patients with multiple organ involved had worse prognosis. The higher SUVmax, SUVpeak, TLG and MTV of lesions, the worse prognosis of patients were found.

The value of 18 F-FDG PET/CT in diagnosing and localising deep sternal wound infection to guide surgical debridement.

Deep sternal wound infection (DSWI) is a severe complication in patients after open heart surgery (OHS). But there is a lack of appropriate imaging tool to detect the infection sites, which may lead to incomplete debridement. The present study aims to investigate the value of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT) in comparison with CT scan in diagnosing and localising DSWI. A total of 102 patients with DSWI after OHS were retrospectively collected from January 2012 to December 2017 in our hospital. All the patients had surgical debridements for DSWI with pretreatment imaging of either 18 F-FDG PET/CT or CT scan. The sensitivity, specificity, and accuracy of localising infection sites were compared between PET/CT and CT groups, with surgical, microbiological, and histopathological findings as the gold standard. The length of hospital stays and the rate of recurrence were also compared. Ten patients in the PET/CT group had a follow-up PET/CT scan after debridement, and the correlations between the changes of PET/CT findings and surgical outcomes were analysed. 18 F-FDG PET/CT is more accurate than CT in diagnosing and localising DSWI after OHS, which leads to a more successful surgical debridement with a lower rate of recurrence and a shorter length of hospital stay. In addition, follow-up PET/CT after debridement could evaluate the treatment effect.

Validation of MR-Based Attenuation Correction of a Newly Released Whole-Body Simultaneous PET/MR System.

The aim of this study was to validate quantitative performance of a newly released simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) scanner, by using MR-based attenuation correction (MRAC), both in phantom study and in patient study. PET/MRI image uniformities of a phantom under different hardware configurations were tested and compared. Thirty patients were examined with 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) PET/computed tomography (CT) and subsequent PET/MRI. PET images from PET/MRI were corrected with MRAC (PETMR), CT-based attenuation maps (µ-maps, PETCT), and segmented CT µ-maps (PETCTSeg) derived from PET/CT. Standardized uptake values (SUVs) were compared among the 3 sets of PET in main organs (bone, liver and lung) and in 52 FDG-avid lesions, including soft-tissue lesions and bone lesions. The result showed that PET imaging uniformities of PET/MRI under different configurations were good (<8.8%). The SUV differences among the 3 sets of PET varied with organs and lesion types. In detail, the mean relative differences of SUV between PETMR and PETCT were as follows: -18.8%, bone (SUVmean); -8.0%, liver (SUVmean); -12.2%, lung (SUVmean); -18.1%, bone lesions (SUVmean); -13.3%, bone lesions (SUVmax); -8.2%, soft-tissue lesions (SUVmean); and -7.3%, soft-tissue lesions (SUVmax). The mean relative differences between PETMR and PETCTSeg were as follows: -19.0%, bone (SUVmean); -3.5%, liver (SUVmean); -3.3%, lung (SUVmean); -19.3%, bone lesions (SUVmean); -17.5%, bone lesions (SUVmax); -5.5%, soft-tissue lesions (SUVmean); and -4.4%, soft-tissue lesions (SUVmax). The differences of SUV between PETMR and PETCT were larger than those between PETMR and PETCTSeg, in both soft tissue and soft-tissue lesions (P < 0.001), but not in bone or bone lesions. In conclusion, MRAC in the newly released PET/MR system is accurate in most tissues, with SUV deviations being generally less than 10%, compared to PET/CT. In bone, however, underestimations can be substantial, which may be partially attributed to segmentation of the MR-based µ-maps.

Impact of patient comfort on diagnostic image quality during PET/MR exam: A quantitative survey study for clinical workflow management.

BACKGROUND: PET/MR is transferring from a powerful scientific research tool to an imaging modality in clinical routine practice. Whole body PET/MR screening usually takes 30-50 minutes to finish, during which a few factors might induce patient discomfort and further cause degraded image quality. The aim of this report is to investigate the patients' perception of the imaging procedure and its correlation with image quality. METHODS: One hundred and twenty patients (63 males and 57 females, average age = 51.3 years, range 22-70 years) who had been diagnosed with cancer or had previous history of cancer were recruited and scanned with a simultaneous PET/MR system. A questionnaire was given to all patients retrospectively after the PET/MR scan, which has nine questions to assess patients' feeling of the scan on a Likert scale scoring system (1-5, 1 as most satisfied). All PET/MR images were also visually examined by two experts independently to evaluate the quality of the images. Six body locations were assessed and each location was evaluated also with a Likert scale scoring system (1-5, 5 as the best quality). Mann-Whitney U-test was used for statistical analysis to check if there is significant correlation between image quality and patient perceptions. RESULTS: With a total of 120 patients, 118 questionnaires were filled and returned for analysis. The patients' characteristics were summarized in Table 4. The statistics of the patients' perception in the questionnaire were illustrated in Tables 5-7. Statistical significant correlations were found between MR image quality and patients' characteristics/perception. CONCLUSION: Our results show that PET/MR scanning is generally safe and comfortable for most of the patients. Statistical analysis does not support the hypothesis that bad patient's perception leads to degraded image quality.

Zero-Extra-Dose PET Delayed Imaging with Data-Driven Attenuation Correction Estimation.

PURPOSE: Delayed positron emission tomography (PET) imaging may improve sensitivity and specificity in lesion detection. We proposed a PET data-driven method to estimate the attenuation map (AM) for the delayed scan without an additional x-ray computed tomography (CT). PROCEDURES: An emission-attenuation-scatter joint estimation framework was developed. Several practical issues for clinical datasets were addressed. Particularly, the unknown scatter correction was incorporated in the joint estimation algorithm. The scaling problem was solved using prior information from the early CT scan. Fourteen patient datasets were added to evaluate the method. These patients went through two separate PET/CT scans. The delayed CT-based AM served as ground truth for the delayed scan. Standard uptake values (SUVmean and SUVmax) of lesion and normal tissue regions of interests (ROIs) in the early and delayed phase and the respective %DSUV (percentage change of SUVmean at two different time points) were analyzed, all with estimated and the true AM. Three radiologists participated in lesion detection tasks with images reconstructed with both AMs and rated scores for detectability. RESULTS: The mean relative difference of SUVmean in lesion and normal liver tissue were 3.30 and 6.69 %. The average lesion-to-background contrast (detectability) with delayed PET images using CT AM was 60 % higher than that of the earlier PET image, and was 64 % higher when using the data-based AM. %DSUV for lesions and liver backgrounds with CT-based AM were - 0.058 ± 0.25 and - 0.33 ± 0.08 while with data-based AM were - 0.00 ± 0.26 and - 0.28 ± 0.08. Only slight significance difference was found between using CT-based AM and using the data-based AM reconstruction delay phase on %DSUV of lesion. The scores associated with the two AMs matched well consistently. CONCLUSIONS: Our method may be used in delayed PET imaging, which allows no secondary CT radiation in delayed phase. The quantitative analysis for lesion detection purpose could be ensured.

Diagnostic accuracy of imaging modalities in differentiating xanthogranulomatous cholecystitis from gallbladder cancer.

BACKGROUND: The aim of this study was to assess the diagnostic performance of radiological imaging in differentiating xanthogranulomatous cholecystitis (XGC) from gallbladder cancer (GBC). METHODS: A retrospective analysis of the radiological imaging performed in patients who had pathologically confirmed XGC or GBC between December 2004 to April 2016 was performed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging modality, and combined imaging modalities were calculated. RESULTS: A total of 218 patients (XGC =109, GBC =109) were identified; 19 patients received all of abdominal ultrasound (US), contrast-enhanced ultrasound (CEUS), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET/CT); 21 received four of these imaging examination types; 45 received three examinations; 58 received two examinations; and 75 received only one examination. The sensitivity and specificity of CEUS was 90% and 93%, respectively, higher than abdominal US (80%, 86%), CT (71%, 92%), MRI (75%, 90%), and PET/CT (55%, 90%) (all values respective). The sensitivity, specificity, NPV, and PPV of the US combined with CEUS were 91%, 90%, 94%, and 85%, respectively. Although the specificity of CEUS + CT and CEUS + MRI were 100% and 92%, respectively, the sensitivity of CEUS + CT and CEUS + MRI were both only 67%. CONCLUSIONS: The Abdominal US is not sufficiently accurate to confidently guide clinical practice, and CEUS showed better diagnostic performance than the other imaging modalities in differentiating XGC from GBC. The combination of abdominal CEUS and CT is helpful for differential diagnosis, as it indicates GBC with better specificity and PPV.

Nineteen cases with synchronous multiple primary cancers studied by 18F-FDG PET/CT.

OBJECTIVE: To evaluate the value of fluorine -18-fuoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in evaluating synchronous multiple primary cancers (SMPC). METHODS: Nineteen patients with pathologically-confirmed SMPC were collected. Clinical and 18F-FDG PET/CT characteristics of these patients were reviewed and analyzed. Maximum standardized uptake value, (SUVmax) of all lesions was measured and difference (Δ)SUVmax between the SUV of two primary tumors in each patient was calculated as: [(the larger SUVmax - the smaller SUVmax)/ the larger SUVmax]×100%. RESULTS: A total of 38 lesions were identified, which were most frequently located in gastrointestinal tract (n=16), followed by lung (n=10), breast (n=4), kidney (n=4), liver (n=2), pancreas (n=1) and thyroid (n=1). Pathologies of these 38 lesions were 18 adenocarcinomas, 8 squamous cell carcinomas, 4 breast invasive ductal carcinomas, 4 renal cell carcinomas, 2 hepatocellular carcinomas, 1 pancreatic ductal adenocarcinoma and 1 papillary thyroid carcinoma. The mean SUVmax of all lesions was 8.5±6.9, most of them being more than 2.5 (n=30). The mean ΔSUVmax was 57.3%±24.6%, indicating different metabolism of the primary cancers in each patient. CONCLUSION: In our center, SMPC most commonly involved the gastrointestinal tract and adenocarcinomas were the most common pathology type. 18F-FDG PET/CT was useful in the diagnosis of SMPC and the ΔSUVmax indicates different pathological origins of the synchronous cancers.

High-Pitch Dual-Source Computed Tomography Renal Angiography Comparison With Conventional Low-Pitch Computed Tomography Angiography: Image Quality, Contrast Medium Volume, and Radiation Dose.

OBJECTIVE: The objective of this study was to compare the image quality (IQ), contrast medium (CM) volume, and radiation dose of the high-pitch renal computed tomography angiography (CTA) with low-pitch protocol. METHODS: Fifty patients underwent renal CTA on a dual-source 128-slice scanner via a high-pitch mode (pitch = 2.05) with 0.5-mL/kg CM injection, whereas 50 patients were also scanned on the same scanner with low-pitch (pitch = 0.6) and 1.0 mL/kg CM injection. Subjective IQ was evaluated. Objective IQ was determined by the signal-to-noise ratio and contrast-to-noise ratio. Effective radiation dose was also evaluated. RESULTS: The contrast-to-noise ratio and signal-to-noise ratio values as well as the IQ scores between the 2 groups had no significant differences (P > 0.05). The effective radiation dose of the high-pitch group was significantly lower (P < 0.05). CONCLUSIONS: High-pitch scan can provide similar subjective and objective IQ compared with low-pitch protocol for renal CTA, whereas CM volume and radiation exposure were significantly reduced.

Detection of vulnerable atherosclerosis plaques with a dual-modal single-photon-emission computed tomography/magnetic resonance imaging probe targeting apoptotic macrophages.

Atherosclerosis (AS), especially the vulnerable AS plaque rupture-induced acute obstructive vascular disease, is a leading cause of death. Accordingly, there is a need for an effective method to draw accurate predictions about AS progression and plaque vulnerability. Herein we report on an approach to constructing a hybrid nanoparticle system using a single-photon-emission computed tomography (SPECT)/magnetic resonance imaging (MRI) multimodal probe, aiming for a comprehensive evaluation of AS progression by achieving high sensitivity along with high resolution. Ultrasmall superparamagnetic iron oxide (USPIO) was covered by aminated poly(ethylene glycol) (PEG) and carboxylated PEG simultaneously and then functionalized with diethylenetriaminepentacetate acid for (99m)Tc coordination and subsequently Annexin V for targeting apoptotic macrophages abundant in vulnerable plaques. The in vivo accumulations of imaging probe reflected by SPECT and MRI were consistent and accurate in highlighting lesions. Intense radioactive signals detected by SPECT facilitated focus recognization and quantification, while USPIO-based T2-weighted MRI improved the focal localization and volumetry of AS plaques. For subsequent ex vivo planar images, targeting effects were further confirmed by immunohistochemistry, including CD-68 and TUNEL staining; meanwhile, the degree of concentration was proven to be statistically correlated with the Oil Red O staining results. In conclusion, these results indicated that the Annexin V-modified hybrid nanoparticle system specifically targeted the vulnerable AS plaques containing apoptotic macrophages and could be of great value in the invasively accurate detection of vulnerable plaques.

Gastric cancer staging with dual energy spectral CT imaging.

PURPOSE: To evaluate the clinical utility of dual energy spectral CT (DEsCT) in staging and characterizing gastric cancers. MATERIALS AND METHODS: 96 patients suspected of gastric cancers underwent dual-phasic scans (arterial phase (AP) and portal venous phase (PP)) with DEsCT mode. Three types of images were reconstructed for analysis: conventional polychromatic images, material-decomposition images, and monochromatic image sets with photon energies from 40 to 140 keV. The polychromatic and monochromatic images were compared in TNM staging. The iodine concentrations in the lesions and lymph nodes were measured on the iodine-based material-decomposition images. These values were further normalized against that in aorta and the normalized iodine concentration (nIC) values were statistically compared. Results were correlated with pathological findings. RESULTS: The overall accuracies for T, N and M staging were (81.2%, 80.0%, and 98.9%) and (73.9%, 75.0%, and 98.9%) determined with the monochromatic images and the conventional kVp images, respectively. The improvement of the accuracy in N-staging using the keV images was statistically significant (p<0.05). The nIC values between the differentiated and undifferentiated carcinoma and between metastatic and non-metastatic lymph nodes were significantly different both in AP (p = 0.02, respectively) and PP (p = 0.01, respectively). Among metastatic lymph nodes, nIC of the signet-ring cell carcinoma were significantly different from the adenocarcinoma (p = 0.02) and mucinous adenocarcinoma (p = 0.01) in PP. CONCLUSION: The monochromatic images obtained with DEsCT may be used to improve the N-staging accuracy. Quantitative iodine concentration measurements may be helpful for differentiating between differentiated and undifferentiated gastric carcinoma, and between metastatic and non-metastatic lymph nodes.

Spectral CT imaging of myocardial infarction: preliminary animal experience.

OBJECTIVES: To evaluate the capability of spectral CT imaging to detect the different stages and angiogenesis of myocardial infarction (MI). METHODS: MI was surgically induced in 40 rabbits that were evenly divided into four stages of MI: 6 h (6H), 3 days (3D), 7 days (7D) and 14 days (14D). Spectral CT was performed at 10 s, 1 min and 3 min after intravenous contrast medium administration. CD31 immunohistochemistry was used for the microvessel density (MVD) measurement. Iodine concentrations in the myocardium were measured and normalised to the aorta as nIC. The relationships between infarcted myocardial nIC and MVD were analysed. RESULTS: The nIC of infarct myocardium decreased at 10 s and increased in late-phase CT images. There were significant differences between the 6H and other groups (P ( 6H-3D ) = 0.01, P ( 6H-7D ) = 0.01, P ( 6H-14D ) = 0.00). There was a significant difference in the MVD of infarct myocardium between the two groups except in the 7D and 14D groups (P = 0.08). In the 10-s phase, the nIC of infarct myocardium was negatively correlated with MVD (r = -0.54, P = 0.00), whereas in the late phases, there was a positive correlation between them (r = 0.57, P = 0.00 in the 1-min phase, r = 0.48, P = 0.00 in the 3-min phase). CONCLUSION: Spectral CT imaging of the myocardium can be used to evaluate the different stages and angiogenesis of MI.

F-18 labeled vasoactive intestinal peptide analogue in the PET imaging of colon carcinoma in nude mice.

As large amount of vasoactive intestinal peptide (VIP) receptors are expressed in various tumors and VIP-related diseases, radiolabeled VIP provides a potential PET imaging agent for VIP receptor. However, structural modification of VIP is required before being radiolabeled and used for VIP receptor imaging due to its poor in vivo stability. As a VIP analogue, [R(8, 15, 21), L(17)]-VIP exhibited improved stability and receptor specificity in preliminary studies. In this study, F-18 labeled [R(8,15,21), L(17)]-VIP was produced with the radiochemical yield being as high as 33.6% ± 3% (decay-for-corrected, n = 5) achieved within 100 min, a specific activity of 255 GBq/ µmol, and a radiochemical purity as high as 99% as characterized by radioactive HPLC, TLC, and SDS-Page radioautography. A biodistribution study in normal mice also demonstrated fast elimination of F-18 labeled [R(8,15,21), L(17)]-VIP in the blood, liver, and gastrointestinal tracts. A further micro-PET imaging study in C26 colon carcinoma bearing mice confirmed the high tumor specificity, with the tumor/muscle radioactivity uptake ratio being as high as 3.03 at 60 min following injection, and no apparent radioactivity concentration in the intestinal tracts. In addition, blocking experiment and Western Blot test further confirmed its potential in PET imaging of VIP receptor-positive tumor.