Right ventricular 18F-FDG uptake is an important indicator for cardiac involvement in patients with suspected cardiac sarcoidosis

Purpose

Cardiac sarcoidosis is most commonly found in the left ventricular (LV) free wall. Presence in the right ventricle (RV) is less common but might be useful for detecting cardiac involvement of sarcoidosis. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET has been used to detect LV regions with cardiac sarcoidosis. However, the same has not been done for RV involvement. The aims of the current study were to evaluate RV ¹⁸F-FDG uptake and its relationship to the distribution of LV wall ¹⁸F-FDG-positive segments in the LV, and to evaluate whether patients with positive RV ¹⁸F-FDG uptake met the 1993 diagnostic criteria of the Japanese Ministry of Health and Welfare (JMHW) guidelines regarding sarcoidosis with suspected cardiac involvement.

Method

Fifty-nine biopsy-proven extra-cardiac sarcoidosis patients (age 56.1 ± 14.7 years) with suspected cardiac involvement based on abnormal electrocardiography or echocardiography findings underwent fasting ¹⁸F-FDG PET or PET/CT. The LV wall was divided into 17 segments and RV uptake was also evaluated.

Result

Among 59 patients, 35 (59.3 %) showed some abnormal ¹⁸F-FDG uptake in the RV and/or LV wall. With respect to the RV wall, 13 (22.0 %) showed abnormal ¹⁸F-FDG uptake. The number of LV-involved segments was 4.8 ± 2.4 in the patients with RV ¹⁸F-FDG uptake, which was significantly higher than in the patients without RV uptake, 1.8 ± 2.2 (P < 0.0001). Patients with RV uptake more frequently met the diagnostic criteria of the 1993 JMHW guidelines (n = 27), than did those without RV uptake (84.6 vs. 34.8 %, P = 0.0033).

Conclusion

¹⁸F-FDG PET identified RV involvement less frequently than LV involvement in this study population. However, patients who had RV uptake showed a greater number of LV-involved segments and met the JMHW diagnostic criteria more frequently. Although RV uptake is less frequent, ¹⁸F-FDG RV uptake may be useful in diagnosing cardiac involvement in sarcoidosis.

Clinical trial registration

UMIN000006533.     

Quantitative interpretation of FDG PET/CT with myocardial perfusion imaging increases diagnostic information in the evaluation of cardiac sarcoidosis

Background

FDG PET/CT with myocardial perfusion imaging is a useful method for evaluating cardiac sarcoidosis (CS), but interpretation is not standardized. We developed a method for quantification of cardiac FDG PET/CT and evaluated its relationship to conventional interpretation, perfusion defects, clinical events, and immunosuppressive treatment.

Methods and Results

FDG PET/CT with MPI studies performed for CS (n = 38) were retrospectively compared to negative control studies acquired for oncologic indications (n = 10). Quantitative measures of FDG volume-intensity (Cardiac Metabolic Activity, CMA) was performed using standardized uptake values (SUVs). CMA (477.7 ± 909 vs 0.55 ± 2.1 vs 0.3 ± 0.3 g glucose, P = .02) was significantly greater in visually FDG-positive studies compared to visually negative and oncologic negative studies. Among patients with CS, CMA was greater in studies with an EF < 50% (760.3 ± 1,148 vs 87.4 ± 161 g glucose, P = .03) and preceding an adverse clinical event (1,095 ± 1,253 vs 73 ± 144 g glucose, P = .006). CMA was the only independent predictor of events by multivariate analysis. In patients with repeat examinations (n = 7), CMA decreased with prednisone treatment in 5 of 6 patients.

Conclusions

Quantification of FDG uptake in CS correlates with lower EFs, clinical events, and immunosuppression treatment.     

Role of 2-[18F]fluoro-2-deoxyglucose positron emission tomography in preoperative management of solid-type small-sized lung cancer

Objective

2-[18F]Fluoro-2-deoxyglucose positron emission tomography (FDG-PET) is routinely used for the diagnosis of primary lung cancer. However, the role of FDG-PET in the diagnosis and staging of small-sized lung cancer has not been sufficiently evaluated. The purpose of this study was to determine the utility of FDG-PET for preoperative staging of solid-type small-sized lung cancer manifesting as solid-component predominant nodules.

Methods

One-hundred and eighteen patients with solid-type small-sized (≤2 cm) lung cancer diagnosed as clinical stage IA based on thin-slice computed tomography (TS-CT) were included in this study. Before surgery, FDG-PET was performed in 78 patients (CT/PET group), and TS-CT alone was performed in 40 patients (CT group). Clinical and pathological stage and prognosis were retrospectively reviewed according to whether FDG-PET had been performed.

Results

No significant differences in clinical factors were observed when comparing the CT/PET group and the CT group. Of the 78 patients in the CT/PET group, 12 (15.4 %) were diagnosed with clinical stage IIA or IIIA disease based on FDG-PET findings, but no advanced cases with contraindications for curative surgery were seen. In the CT/PET group, the pathological stage was IA in 66 patients, IB in eight patients, IIA in one patient, and IIIA in three patients; 16 patients had incorrectly staged disease. The accurate staging rate was 79.5 % for the CT–PET group and 70.0 % for the CT group (P = 0.262). Among patients diagnosed with clinical stage IA disease, the 3-year overall survival rate was 85.5 % for the 66 patients in the CT/PET group and 76.8 % for the 40 patients in the CT group (P = 0.554). No significant difference was observed in accuracy of preoperative staging and prognosis between the two groups.

Conclusions

FDG-PET produced no clear benefit for the preoperative management of patients with solid-type clinical T1aN0M0 lung cancer, in terms of postoperative survival and the concordance rate of clinical and pathological stage.     

Current clinical use of 18FDG-PET/CT in patients with thoracic and systemic sarcoidosis

Purpose

This study assessed the role of whole-body ¹⁸fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸FDG PET/CT) in the restaging and follow-up of patients with sarcoidosis previously studied by multidetector computed tomography (MDCT).

Materials and methods

This retrospective study enroled 21 patients to evaluate the sensitivity, specificity and accuracy of ¹⁸FDG-PET/CT and MDCT. The results of the two techniques were compared with the Mc Nemar test. Cohen’s K was used to compare concordance at the different lesion sites.

Results

The sensitivity, specificity and accuracy of ¹⁸FDG-PET/CT were 80, 66.67, and 76.19 %, respectively. The sensitivity, specificity and accuracy of MDCT were 93.33, 33.33, and 76.19 %, respectively. In 16 patients who underwent whole-body MDCT, the sensitivity, specificity and accuracy values were 91.67, 81.25, and 50 % (MDCT) and 100, 50, and 87.5 % (¹⁸FDG-PET/CT).

Conclusions

¹⁸FDG-PET/CT is useful in evaluating the extent of sarcoidosis and recognising lesions at different sites, including lymph nodes, lungs, liver, spleen and bone. It also improves the interpretation of the morphological lesions seen on MDCT and depicts a larger number of lesions. Therefore, ¹⁸FDG-PET/CT could be used to complement other more traditional techniques for the restaging and follow-up in patients with sarcoidosis.     

Radiation exposure and risk–benefit analysis in cancer screening using FDG-PET: results of a Japanese nationwide survey

Objective

The aim of this study was to estimate radiation exposure and evaluate the risks and benefits of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in cancer screening.

Methods

A nationwide survey of FDG-PET cancer screening was conducted in 2006, and the results were analyzed with a common index, “extension/shortening of the average life expectancy.”

Results

The average estimated effective dose was 4.4 mSv (male 4.7 mSv; female 4.0 mSv) for dedicated PET and 13.5 mSv (male 14.2 mSv; female 12.8 mSv) for PET/computed tomography (CT). The risk–benefit break-even age from the viewpoint of radiation exposure was in the 40s for men and 30s for women for dedicated PET and in the 50s for men and 50s (variable injection dose) or 60s (constant injection dose) for women for PET/CT.

Conclusions

FDG-PET cancer screening is beneficial for examinees above the break-even ages. The risks and benefits should be explained to examinees because of the larger radiation used in cancer FDG-PET screening compared with other X-ray tests.     

F-18 FDG-PET/CT in evaluation of patients with fever of unknown origin

Objectives

This study was carried out to evaluate the diagnostic utility of FDG-PET/CT in patients with fever of unknown origin (FUO).

Methods

Medical records of 103 patients who underwent FDG-PET/CT and anatomic imaging as a part of FUO workup were analyzed. Final diagnosis of the cause of FUO was reached based on serologic assays, cultures, biopsy, surgery or 6 months of clinical follow-up.

Results

The definite cause of fever was established in 69/103 patients. Abnormal FDG uptake was found in 63/103 patients and contributed to the final diagnosis (TP) in 62 patients (98.48 %). Of the remaining 40 patients with negative PET/CT, the final definite cause of fever (FN) could be determined only in seven patients (17.5 %). PET/CT had a sensitivity, specificity, positive predictive value and negative predictive value of 90, 97, 98.4 and 82.5 % compared to 43.5, 67.6, 73.2 and 37.1 %, respectively, for anatomic imaging. FDG-PET/CT had a higher accuracy (92.2 vs. 51.5 %; p = 0.003) compared to anatomic imaging for suggesting a cause of FUO.

Conclusions

PET/CT showed high sensitivity and specificity in suggesting a definite diagnosis in the evaluation of FUO.     

The response of FDG uptake to immunosuppressive treatment on FDG PET/CT imaging for cardiac sarcoidosis

Background

Immunosuppression is used to treat cardiac sarcoidosis, despite limited data. FDG PET/CT is used for detecting cardiac inflammation in patients with CS, yet there is variability in interpretation of FDG PET/CT. Our aim was to compare quantitative and qualitative interpretation of FDG PET/CT for CS in defining the FDG response to immunosuppression.

Methods and Results

Patients with CS (N = 43 total studies from 17 patients) had serial FDG PET/CT studies before/after immunosuppression. FDG uptake was analyzed qualitatively (visually; FDG-positive segments) and quantitatively (SUVmax; cardiac metabolic volume and activity (CMV, CMA); volume above SUV thresholds 2.7 and 4.1 g/mL). Complete resolution of FDG uptake was common using CMA (10/17), CMV (10/17), but a 2.7 g/mL SUV threshold (13/17) and SUVmax (14/17) were more likely to define partial responses. In six patients imaged after a reduction in immunosuppression, 4/6 had a rebound quantitative FDG uptake.

Conclusions

Quantitative interpretation of FDG PET/CT in CS can detect changes in FDG uptake in response to immunosuppression. Further studies are needed to see if quantitative changes in FDG uptake are associated with improved outcomes.

     

The usefulness of 18F-FDG PET/MRI fusion image in diagnosing pancreatic tumor: comparison with 18F-FDG PET/CT

Purpose

This study aimed at demonstrating the feasibility of retrospectively fused ¹⁸F FDG-PET and MRI (PET/MRI fusion image) in diagnosing pancreatic tumor, in particular differentiating malignant tumor from benign lesions. In addition, we evaluated additional findings characterizing pancreatic lesions by FDG-PET/MRI fusion image.

Methods

We analyzed retrospectively 119 patients: 96 cancers and 23 benign lesions. FDG-PET/MRI fusion images (PET/T1 WI or PET/T2WI) were made by dedicated software using 1.5 Tesla (T) MRI image and FDG-PET images. These images were interpreted by two well-trained radiologists without knowledge of clinical information and compared with FDG-PET/CT images. We compared the differential diagnostic capability between PET/CT and FDG-PET/MRI fusion image. In addition, we evaluated additional findings such as tumor structure and tumor invasion.

Results

FDG-PET/MRI fusion image significantly improved accuracy compared with that of PET/CT (96.6 vs. 86.6 %). As additional finding, dilatation of main pancreatic duct was noted in 65.9 % of solid types and in 22.6 % of cystic types, on PET/MRI-T2 fusion image. Similarly, encasement of adjacent vessels was noted in 43.1 % of solid types and in 6.5 % of cystic types. Particularly in cystic types, intra-tumor structures such as mural nodule (35.4 %) or intra-cystic septum (74.2 %) were detected additionally. Besides, PET/MRI-T2 fusion image could detect extra benign cystic lesions (9.1 % in solid type and 9.7 % in cystic type) that were not noted by PET/CT.

Conclusions

In diagnosing pancreatic lesions, FDG-PET/MRI fusion image was useful in differentiating pancreatic cancer from benign lesions. Furthermore, it was helpful in evaluating relationship between lesions and surrounding tissues as well as in detecting extra benign cysts.     

Feasibility of FDG-PET in myocarditis: Comparison to CMR using integrated PET/MRI

Objective

Besides cardiac sarcoidosis, FDG-PET is rarely used in the diagnosis of myocardial inflammation, while cardiac MRI (CMR) is the actual imaging reference for the workup of myocarditis. Using integrated PET/MRI in patients with suspected myocarditis, we prospectively compared FDG-PET to CMR and the feasibility of integrated FDG-PET/MRI in myocarditis.

Methods

A total of 65 consecutive patients with suspected myocarditis were prospectively assessed using integrated cardiac FDG-PET/MRI. Studies comprised T2-weighted imaging, late gadolinium enhancement (LGE), and simultaneous PET acquisition. Physiological glucose uptake in the myocardium was suppressed using dietary preparation.

Results

FDG-PET/MRI was successful in 55 of 65 enrolled patients: two patients were excluded due to claustrophobia and eight patients due to failed inhibition of myocardial glucose uptake. Compared with CMR (LGE and/or T2), sensitivity and specificity of PET was 74% and 97%. Overall spatial agreement between PET and CMR was κ = 0.73. Spatial agreement between PET and T2 (κ = 0.75) was higher than agreement between PET and LGE (κ = 0.64) as well as between LGE and T2 (κ = 0.56).

Conclusion

In patients with suspected myocarditis, FDG-PET is in good agreement with CMR findings.

     

Arterial inflammation in bronchial asthma

Background

Bronchial asthma is a chronic inflammatory condition associated with increased cardiovascular (CV) events. Here, we assess arterial inflammation, using 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging (FDG-PET/CT), in patients with bronchial asthma and low to intermediate Framingham risk scores (FRS).

Methods

A total of 102 patients underwent FDG-PET/CT imaging for clinical indications. Thirty-four patients (mean age 54.9 ± 16.1) with mild asthma and no known atherosclerotic disease were compared to 2 non-asthmatic groups. The first control group (n = 34) were matched by age, gender, and FRS. The second control group (n = 34) had clinical atherosclerosis and were matched by gender. Thereafter, arterial FDG uptake on PET images was determined, while blinded to patient identifiers.

Results

Target-to-background-ratio (TBR) in the aorta was higher in asthmatics vs non-asthmatic FRS-matched controls (1.96 ± 0.26 vs 1.76 ± 0.20; P < .001). The aortic TBR remained elevated in asthmatics vs non-asthmatic controls after adjusting traditional CV risk factors (P < .001). An inverse correlation was observed between FDG uptake and lung function, FEV₁ (P = .02) and peak flow (P = .03).

Conclusions

Bronchial asthma is associated with increased arterial inflammation beyond that estimated by current risk stratification tools. Further studies are required to evaluate whether attenuation of systemic inflammation will decrease CV events.     

Preoperative staging of non-small cell lung cancer: prospective comparison of PET/MR and PET/CT

Objectives

To prospectively compare the accuracies of PET/MR and PET/CT in the preoperative staging of non-small cell lung cancer (NSCLC).

Methods

Institutional review board approval and patients’ informed consents were obtained. 45 patients with proven or radiologically suspected lung cancer which appeared to be resectable on CT were enrolled. PET/MR was performed for the preoperative staging of NSCLC followed by PET/CT without contrast enhancement on the same day. Dedicated MR images including diffusion weighted images were obtained. Readers assessed PET/MR and PET/CT with contrast-enhanced CT. Accuracies of PET/MR and PET/CT for NSCLC staging were compared.

Results

Primary tumour stages (n?=?40) were correctly diagnosed in 32 patients (80.0 %) on PET/MR and in 32 patients (80.0 %) on PET/CT (P?=?1.0). Node stages (n?=?42) were correctly determined in 24 patients (57.1 %) on PET/MR and in 22 patients (52.4 %) on PET/CT (P?=?0.683). Metastatic lesions in the brain, bone, liver, and pleura were detected in 6 patients (13.3 %). PET/MR missed one patient with pleural metastasis while PET/CT missed one patient with solitary brain metastasis and two patients with pleural metastases (P?=?0.480).

Conclusions

This study demonstrated that PET/MR in combination with contrast-enhanced CT was comparable to PET/CT in the preoperative staging of NSCLC while reducing radiation exposure.

Key points

? PET/MR can be comparable to PET/CT for preoperative NSCLC staging.? PET/MR and PET/CT show excellent correlation in measuring SUVmax of primary lesions.? Using PET/MR, estimated radiation dose can decrease by 31.1?% compared with PET/CT.

     

Comparison of integrated whole-body PET/MR and PET/CT: Is PET/MR alternative to PET/CT in routine clinical oncology?

Purpose

To compare the diagnostic accuracy of whole-body PET/CT and integrated PET/MR in relation to the total scan time durations.

Methods

One hundred and twenty-three (123) patients (40 males and 83 females; mean age 59.6 years; range 20–83 years) with confirmed primary cancer and clinical suspicion of metastatic disease underwent whole-body 18F-FDG-PET/CT and 18F-FDG-PET/MR. Data acquisition was done after intravenous administration of 110–301 MBq radioactivity of 18F-FDG, and PET/MR data were acquired after the PET/CT data acquisition. The mean uptake times for PET/CT and PET/MR acquisition were 68.0 ± 8.0 and 98.0 ± 14 min, respectively. Total scan time was 20.0 and 25.0 min for whole-body PET/CT and PET/MR imaging.

Results

The reconstructed PET/CT and PET/MR data detected 333/355 (93.8 %) common lesions in 111/123 (90.2 %) patients. PET/CT and PET/MR alone detected 348/355 and 340/355 lesions, respectively. No significant (p = 0.08) difference was observed for the overall detection efficiency between the two techniques. On the other hand, a significant difference was observed between the two techniques for the detection of lung (p = 0.003) and cerebrospinal (p = 0.007) lesions. The 15 lesions identified by PET/CT only included 8 lung, 3 lymph nodes, 2 bone, and 1 each of peritoneal and adrenal gland lesions. On the other hand, 7 (6 brain metastatic lesions and 1 bone lesion) were identified by PET/MR only.

Conclusion

Integrated PET/MR is a feasible whole-body imaging modality and may score better than PET/CT for the detection of brain metastases. To further prove diagnostic utility, this technique requires further clinical validation.

     

Additional value of integrated PET/CT over PET alone in the initial staging and follow up of head and neck malignancy

Objective

Clinical application of FDG-PET in head and neck cancer includes identification of metastases, unknown primary head and neck malignancy, or second primary carcinoma, and also recurrent tumor after treatment. In this study, the additional value of PET/CT fusion images over PET images alone was evaluated in patients with initial staging and follow up of head and neck malignancy.

Methods

Forty patients with suspected primary head and neck malignancy and 129 patients with suspected relapse after treatment of head and neck malignancy were included. FDG-PET/CT study was performed after the intravenous administration of FDG (5 MBq/kg). Target of evaluation was set at primary tumor, cervical lymph node, and whole body. PET images and PET with CT fusion images were compared. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Results of PET and PET/CT were compared with postoperative histopathological examination, and case by case comparison of PET and PET/CT results for each region was performed. The additional value of CT images over PET only images was assessed. Statistical differences in sensitivity and specificity were evaluated.

Results

In the comparative evaluation of 507 targets by PET alone and PET/CT, 401 targets showed agreement of the results. Of the 106 discordant targets, 103 showed a positive result on PET alone and negative result on PET/CT. These results showed a significant difference (p < 0.01). Sensitivity of PET/CT was slightly higher than that of PET without statistical significance, while specificity of PET/CT was significantly higher than that of PET alone (Initial staging: 90.5% vs. 62.2%, p < 0.01; Follow up: 97.2% vs. 74.4%, p < 0.01). In Fisher’s direct probability test, a significant difference was noted in the sensitivity (Initial staging: 91.3% vs. 87.0%, p < 0.01; Follow up: 93.9% vs. 91.4%, p < 0.01).

Conclusions

Combined PET/CT showed improved diagnostic performance than PET alone by decreasing the number of false positive findings in patients with initial staging and follow up of head and neck malignancy.     

Comparison of FDG-PET, MRI and CT for post radiofrequency ablation evaluation of hepatic tumors

Purpose

Treatment effect of radiofrequency ablation (RFA) is traditionally accomplished with MRI and/or CT. The aim of the study was to assess the role of FDG-PET in post RFA hepatic tumor evaluation, in comparison with MRI and CT.

Materials and methods

28 patients (33 hepatic RFA lesions) who had post RFA FDG-PET within 8 weeks of abdominopelvic MRI or CT were retrospectively reviewed. Accuracy of FDG-PET on post hepatic RFA evaluation was compared with MRI and/or CT based on clinical and imaging follow-up.

Results

Among total of 33 RFA-treated lesions, 17 had residual or recurrent tumor (positive). PET identified 16 with a sensitivity of 94.1 %. Of these 17 lesions, 12 had concurrent MRI and 8 were positive with a sensitivity of 66.7 %. Similarly, 6 out of the 17 lesions had CT and 4 were positive with a sensitivity of 66.7 %. Sixteen lesions were successfully ablated (negative). Among them FDG-PET was negative in 13 with a specificity of 81.3 %; MRI was performed in 8 and 7 were negative with a specificity of 87.5 %; CT was performed in 8 and 5 were negative with a specificity of 62.5 %. The overall accuracy of PET, MRI and CT was 87.9, 75.0, and 64.3 %, respectively. The average scan numbers for PET, MRI and CT to achieve a final accurate diagnosis were 1.121, 1.316 and 1.250, with a corresponding cost of $1455.2, $1845.8, and $933.8, respectively.

Conclusions

The study suggests that FDG-PET is superior to MRI and/or CT and is more cost-effective in post RFA hepatic tumor assessment.     

Prospective head-to-head comparison of <Superscript>11</Superscript>C-choline-PET/MR and <Superscript>11</Superscript>C-choline-PET/CT for restaging of biochemical recurrent prostate cancer

Purpose

Whole-body integrated ¹¹C-choline PET/MR might provide advantages compared to ¹¹C-choline PET/CT for restaging of prostate cancer (PC) due to the high soft-tissue contrast and the use of multiparametric MRI, especially for detection of local recurrence and bone metastases.

Materials and methods

Ninety-four patients with recurrent PC underwent a single-injection/dual-imaging protocol with contrast-enhanced PET/CT followed by fully diagnostic PET/MR. Imaging datasets were read separately by two reader teams (team 1 and 2) assessing the presence of local recurrence, lymph node and bone metastases in predefined regions using a five-point scale. Detection rates were calculated. The diagnostic performance of PET/CT vs. PET/MR was compared using ROC analysis. Inter-observer and inter-modality variability, radiation exposure, and mean imaging time were evaluated. Clinical follow-up, imaging, and/or histopathology served as standard of reference (SOR).

Results

Seventy-five patients qualified for the final image analysis. A total of 188 regions were regarded as positive: local recurrence in 37 patients, 87 regions with lymph node metastases, and 64 regions with bone metastases. Mean detection rate between both readers teams for PET/MR was 84.7% compared to 77.3% for PET/CT (p > 0.05). Local recurrence was identified significantly more often in PET/MR compared to PET/CT by team 1. Lymph node and bone metastases were identified significantly more often in PET/CT compared to PET/MR by both teams. However, this difference was not present in the subgroup of patients with PSA values ≤2 ng/ml.Inter-modality and inter-observer agreement (K > 0.6) was moderate to substantial for nearly all categories. Mean reduction of radiation exposure for PET/MR compared to PET/CT was 79.7% (range, 72.6–86.2%). Mean imaging time for PET/CT was substantially lower (18.4 ± 0.7 min) compared to PET/MR (50.4 ± 7.9 min).

Conclusions

¹¹C-choline PET/MR is a robust imaging modality for restaging biochemical recurrent PC and interpretations between different readers are consistent. It provides a higher diagnostic value for detecting local recurrence compared to PET/CT with the advantage of substantial dose reduction. Drawbacks of PET/MR are a substantially longer imaging time and a slight inferiority in detecting bone and lymph node metastases in patients with PSA values >2 ng/ml. Thus, we suggest the use of ¹¹C-choline PET/MR especially for patients with low (≤2 ng/ml) PSA values, whereas PET/CT is preferable in the subgroup with higher PSA values.

     

Modification of staging and treatment of head and neck cancer by FDG-PET/CT prior to radiotherapy

Background and purpose

Reliable tumor staging is a fundamental pre-requisite for efficient tumor therapy and further prognosis. The aim of this study was to compare head and neck cancer (HNC) staging before and after FDG-PET/CT, evaluating the stage modifications for radiotherapy (RT) planning.

Patients and methods

A total of 102 patients with untreated primary HNC, who underwent conventional staging and staging including FDG-PET/CT before RT, were enrolled in this retrospective study. Blinded pre-FDG-PET/CT and post-FDG-PET/CT staging data were compared. The impact on patient management was tested by comparing the intention before and after FDG-PET/CT.

Results

Significant modifications of T, N, and M stage as well as clinical stage were detected after inclusion of FDG-PET/CT data (p?=?0.002, 0.0006, 0.001, 0.03, respectively). Overall, the implementation of FDG-PET/CT led to modification of RT intention decision in 14 patients.

Conclusions

FDG-PET/CT demonstrates essential influence on tumor staging in HNC patients scheduled for irradiation. Implementation of FDG-PET/CT in imaging protocol improves selection of candidates for curative and palliative RT and allows further optimization of treatment management and therapy intention.     

Evaluation of attenuation correction in cardiac PET using PET/MR

Background

Simultaneous acquisition Positron emission tomography/magnetic resonance (PET/MR) is a new technology that has potential as a tool both in research and clinical diagnosis. However, cardiac PET acquisition has not yet been validated using MR imaging for attenuation correction (AC). The goal of this study is to evaluate the feasibility of PET imaging using a standard 2-point Dixon volume interpolated breathhold examination (VIBE) MR sequence for AC.

Methods and Results

Evaluation was performed in both phantom and patient data. A chest phantom containing heart, lungs, and a lesion insert was scanned by both PET/MR and PET/CT. In addition, 30 patients underwent whole-body ¹⁸F-fluorodeoxyglucose PET/CT followed by simultaneous cardiac PET/MR. Phantom study showed 3% reduction of activity values in the myocardium due to the non-inclusion of the phased array coil in the AC. In patient scans, average standardized uptake values (SUVs) obtained by PET/CT and PET/MR showed no significant difference (n = 30, 4.6 ± 3.5 vs 4.7 ± 2.8, P = 0.47). There was excellent per patient correlation between the values acquired by PET/CT and PET/MR (R ² = 0.97).

Conclusions

Myocardial SUVs PET imaging using MR for AC shows excellent correlation with myocardial SUVs obtained by standard PET/CT imaging. The 2-point Dixon VIBE MR technique can be used for AC in simultaneous PET/MR data acquisition.

     

18F-Fluorodeoxyglucose-PET/CT to evaluate tumor, nodal disease, and gross tumor volume of oropharyngeal and oral cavity cancer: comparison with MR imaging and validation with surgical specimen

Introduction

The purpose of this paper is to evaluate the impact of adding combined ¹⁸F-PET/CT to MRI for T and N staging of the oral and oropharyngeal cancer and calculation of the gross tumor volume (GTV) having histopathology as reference standard.

Methods

PET/CT and MRI were performed in 66 patients with suspected oral and oropharyngeal cancer (41 primary tumors/25 recurrent tumors) and nodal disease (114 nodes). Statistical analysis included the McNemar test, sensitivity, specificity for the diagnostic modalities as well as regression analysis, and Bland–Altman graphs for calculated tumor volumes.

Results

There was no statistically significant difference between the two modalities compared to pathological findings regarding detection of disease (P?≥?0.72). The sensitivity/specificity for tumor detection were 100/80% and 96.72/60% for MRI and PET/CT, respectively. The sensitivity/specificity for nodal metastases were 88.46/75% and 83.81/73.91% for MRI and PET/CT, respectively. In 18% of cases, the MRI-based T staging resulted in an overestimation of the pathologic tumor stage. The corresponding rate for PET/CT was 22%. Regarding the treated necks, both modalities showed 100% sensitivity for detection of the recurrent lesions. In necks with histologically N0 staging, MRI and PET/CT gave 22% and 26% false positive findings, respectively. The mean tumor volume in the pathologic specimen was 16.6?±?18.6 ml, the mean volume derived by the MR imaging was 17.6?±?19.1 ml while the estimated by PET/CT volume was 18.8?±?18.1 ml (P?≤?0.007 between the three methods). The Bland–Altman analysis showed a better agreement between PET/CT and MRI.

Conclusion

The diagnostic performance of FDG-PET/CT in the local staging of oral cancer is not superior to MRI.     

Protocol requirements and diagnostic value of PET/MR imaging for liver metastasis detection

Purpose

To compare the accuracy of PET/MR imaging with that of FDG PET/CT and to determine the MR sequences necessary for the detection of liver metastasis using a trimodality PET/CT/MR set-up.

Methods

Included in this single-centre IRB-approved study were 55 patients (22 women, age 61?±?11 years) with suspected liver metastases from gastrointestinal cancer. Imaging using a trimodality PET/CT/MR set-up (time-of-flight PET/CT and 3-T whole-body MR imager) comprised PET, low-dose CT, contrast-enhanced (CE) CT of the abdomen, and MR with T1-W/T2-W, diffusion-weighted (DWI), and dynamic CE imaging. Two readers evaluated the following image sets for liver metastasis: PET/CT (set A), PET/CECT (B), PET/MR including T1-W/T2-W (C), T1-W/T2-W with either DWI (D) or CE imaging (E), and a combination (F). The accuracy of each image set was determined by receiver-operating characteristic analysis using image set B as the standard of reference.

Results

Of 120 liver lesions in 21/55 patients (38 %), 79 (66 %) were considered malignant, and 63/79 (80 %) showed abnormal FDG uptake. Accuracies were 0.937 (95 % CI 89.5 – 97.9 %) for image set A, 1.00 (95 % CI 99.9 – 100.0 %) for set C, 0.998 (95 % CI 99.4 – 100.0 %) for set D, 0.997 (95 % CI 99.3 – 100.0 %) for set E, and 0.995 (95 % CI 99.0 – 100.0 %) for set F. Differences were significant for image sets D – F (P?<?0.05) when including lesions without abnormal FDG uptake. As shown by follow-up imaging after 50 – 177 days, the use of image sets D and both sets E and F led to the detection of metastases in one and three patients, respectively, and further metastases in the contralateral lobe in two patients negative on PET/CECT (P?=?0.06).

Conclusion

PET/MR imaging with T1-W/T2-W sequences results in similar diagnostic accuracy for the detection of liver metastases to PET/CECT. To significantly improve the characterization of liver lesions, we recommend the use of dynamic CE imaging sequences. PET/MR imaging has a diagnostic impact on clinical decision making.     

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.