Integrated Positron Emission Tomography Research Articles

Integrated positron emission tomography and computed tomography in preoperative lymph node staging of non-small cell lung cancer

Background Integrated positron emission tomography and computed tomography (PET/CT) is increasingly used for the preoperative nodal staging of non-smail cell lung cancer (NSCLC). The aim of this study was to evaluate the accuracy of PET/CT in comparison with CT in detection of nodal metastasis and preoperative nodal staging in patients with NSCLC, and to analyze the causes of the PET/CT false-negative and false-positive results. Methods Consecutive patients with pathologically proven NSCLC who underwent staging using PET/CT from July 2008 to February 2012 were evaluated retrospectively. Nodal staging was pathologically confirmed on tissue specimens obtained at thoracotomy. The accuracy of PET/CT and CT in the assessment of intrathoracic nodal involvement was determined using histological results as the reference standard. Logistic regression was used to define the causes of the false-negative and false-positive results. Results A total of 528 lymph node stations were evaluated in 101 patients. Lymph nodes were positive for malignancy in 43 out of 101 patients (42.6%), and 101 out of 528 nodal stations (19.2%). PET/CT was significantly more accurate for nodal staging than CT. The sensitivity, specificity, positive and negative predictive values, and accuracy of PET/CT for detecting nodal metastasis were 51.5%, 95.8%, 74.3%, 89.3%, and 87.3% and the corresponding data by CT were 45.5%, 87.1%, 45.5%, 87.1%, and 79.2%, respectively. PET/CT confers significantly higher specificity, positive predictive value, and accuracy than CT in detecting nodal metastasis. False-negative results by PET/CT are significantly associated with smaller lymph node size, whereas false-positive results are related to a combination of inflammatory disorders and larger lymph node size. Conclusion PET/CT confers significantly higher accuracy than CT in nodal staging, and is more specific and accurate than CT in detecting nodal metastasis but has a low sensitivity and high false-negative rate.

Endobronchial Ultrasound–guided Transbronchial Needle Aspiration for Lymphoma: The Final Frontier

Endobronchial Ultrasound–guided Transbronchial Needle Aspiration for Lymphoma: The Final Frontier

Is there a role for PET-CT and SPECT-CT in pediatric oncology?

During the last decade, hybrid imaging has revolutionized nuclear medicine. Multimodal camera systems, integrating positron emission tomography (PET) or single photon emission computed tomography (SPECT) with computed tomography (CT) now combine the contrast provided by tumor-avid radioactive drugs with the anatomic precision of CT. While PET-CT to a great extent has replaced single-modality PET in adult oncology, the use of PET-CT in children has been controversial, since even the lowest dose CT protocols adds approximately 2 mSv to the radiation dose of about 4 mSv from the PET-study with F-18-fluorodeoxyglucose (F-18-FDG). The article describes the current techniques used, discusses radiation doses and gives an overview of current indications for PET-CT and SPECT-CT in children. Hybrid imaging with a tumor-avid radioactive drug provides extremely high contrast between tumor and background tissues, while the CT component helps to locate the lesion anatomically. Currently both PET-CT and SPECT-CT play a role in pediatric oncology; PET-CT using F-18-FDG particularly for staging and follow-up of lymphoma and brain cancer, bone and soft tissue sarcomas; SPECT-CT with I-123-metaiodobenzylguanidine (MIBG) for tumors of the sympathetic nervous system such as neuroblastoma and pheochromocytoma while the remaining neuroendocrine tumors are imaged with radioactively labeled somatostatin analogues. To reduce radiation dose, a low-dose CT in combination with ultrasound and/or magnetic resonance imaging for the assessment of anatomy is often preferred.

The maximum standardized FDG uptake on PETCT in patients with non-small cell lung cancer

Background: Non-small cell lung cancer (NSCLC) accounts for approximately 80% of new diagnoses of pulmonary carcinoma. This study investigated the correlation between 18 F-fluorodeoxyglucose uptake in computerized tomography integrated positron emission tomography and tumor size, lymph node metastasis, and distant metastasis in patients with NSCLC. Methods: The records of 151 NSCLC patients (139 male, 12 female; mean age 59.60 years) were evaluated retrospectively. Results: Forty-one cases were adenocarcinomas; 45 squamous cell carcinomas; and 65 unspecified NSCLC. When the cases were categorized according to tumor size (group 1, ≤ 3 cm; group 2, > 3 and ≤ 5 cm; group 3, > 5 cm), the maximum standardized uptake value (SUVmax) was significantly lower in groups 1 and 2 compared with group 3 (p = 0.006 for each). Considering all cases, tumor SUVmax was not correlated with age, gender, or histopathological type. Lymph node metastases were pathologically proven in 24 cases: 24% of these were adenocarcinomas, 6% squamous cell carcinomas, and 16% unspecified NSCLC. Neither lymph node involvement nor distant metastases were correlated with tumor SUVmax, although lymph node size was positively correlated with lymph node SUVmax (r = 0.775; p < 0.001). Conclusions: SUVmax was significantly associated with tumor size, but not with distant metastases or lymph node involvement. Therefore, SUVmax on positron emission tomography is not predictive of the presence of metastases.

Phase I study of integrating PET/CT and dose-escalated intensity modulated radiation therapy using a simultaneous integrated boost technique for thoracic esophageal cancer

Background: Esophageal cancer has a poor prognosis because most patients have locally advanced disease upon presentation, and are therefore not suitable for upfront surgery. Modern radiation therapy techniques using intensity modulated radiation therapy (IMRT) combined with a novel imaging technique using integrated positron emission tomography and computed tomography (PET/CT) may help radiation oncologists increase radiation dose to the tumor and may improve tumor response. Objective: The primary aim was to analyze the toxicity of dose-escalated IMRT using a simultaneous integrated boost (SIB) technique and concurrent chemotherapy in esophageal cancer patients using PET/CT as a guide for target delineation. Secondary endpoints were to evaluate response rate, overall survival, and event-free survival rates. Method: Seventeen consecutive patients with locally advanced carcinoma of the esophagus were treated with preoperative concurrent chemoradiation that consisted of IMRT 64 Gy in 30 fractions (SIB technique), together with two cycles of cisplatin (80 mg/m 2 , day 1 and 29) and 5-fluorouracil (1000 mg/m 2 /d, days 1–4 and 29–32). Baseline PET/CT was used for staging and target delineation. After complete chemoradiation for 3 months, PET/CT was repeated and the patients were evaluated for esophagectomy. Treatment toxicities were collected. Baseline and 3-month postchemoradiation PET/CT imaging were analyzed and correlated with the pathological findings. Result: The median follow-up time was 12 months. All 17 patients had squamous cell carcinoma of thoracic esophageal cancer and were treated with chemoradiation. The most common acute ≥grade 3 adverse effects were leucopenia (58.8) and vomiting (23.5%), respectively. Acute ≥grade 3 cardiotoxicities and pulmonary toxicities were observed in 5.9% and 11.7% of the patients, respectively. One patient (5.9%) died from an esophagopericardial fistula. Seven patients underwent esophagectomy after chemoradiation. A pathologic complete remission was achieved in 4 patients (57.1% of the surgical group or 23.5% of the entire group). The overall 1-year survival and event free survival rates for the entire group of patients were 87% and 59%, respectively. There was a statistically significant difference in the overall 1-year survival between surgical and nonsurgical groups (overall 1-year survival, 100% versus 74%, respectively, p = 0.037). In contrast, there was no significant difference in 1-year event-free survival between groups (1-year event-free survival, 72% versus 56%, p = 0.085). Applying the average absolute reduction and percentage reduction of SUV max in these patients, PET/ CT could not predict the pathologic response. Conclusion: Integrating PET/CT for dose-escalated IMRT in esophageal cancer patients showed acceptable toxicities and promising overall survival, especially when followed by surgery.

Pancreatic tuberculosis presenting as an unusual head mass

A 28-year-old man presented with upper abdominal pain accompanied by loss of appetite and weight. The clinical examination was unremarkable. His laboratory investigations revealed serum alkaline phosphatase of 260 IU/l (normal range: 42 – 126 U/L) with normal serum bilirubin. Ultrasound of the abdomen showed a well-defined hypoechoic mass, measuring 3 cm, in the head and body region of the pancreas and a nondilated common bile duct and pancreatic duct. Integrated positron emission tomography (PET)–computed tomography (CT) had similar findings with the mass showing intense 18F-fluorodeoxyglucose (FDG) uptake (standardized uptake value [SUV] value of 15.7) and invading the common hepatic artery as well as the superior mesenteric vein ([Fig. 1]). The peripancreatic and precaval lymph nodes were also enlarged and showed intense FDG uptake. Endoscopic ultrasound (EUS) also had similar findings, with infiltration of the major vessels by the mass ([Fig. 2]). Following EUS-guided fine-needle aspiration from the mass, cytological analysis revealed granulomatous inflammation with negative staining for acid-fast bacilli (AFB) ([Fig. 3]). The patient started four-drug antitubercular therapy (ATT) and showed a marked improvement in symptoms. After 6 weeks of ATT he is asymptomatic with a normal appetite and complete resolution of abdominal pain.

Optimizing Positron Emission Tomography Image Acquisition Protocols in Integrated Positron Emission Tomography/Magnetic Resonance Imaging

In integrated positron emission tomography (PET)/magnetic resonance imaging (MRI), the PET data acquisition is performed simultaneously to the magnetic resonance data acquisition, leaving latitude for the duration of PET acquisition time. This establishes emission time as an important parameter in forthcoming PET/MRI protocols because it is one of the key factors determining PET image quality. Thus, the purpose of the current study was to identify optimal duration of PET acquisition time in PET/MRI. A total of 22 consecutive patients (7 men, 15 women) underwent fluorine-18-labeled fluorodeoxyglucose (18[F]FDG) PET/MRI after clinical PET/computed tomography. Positron emission tomography/magnetic resonance scans were acquired for 8 minutes per bed position (mpb). Positron emission tomography was extracted to reconstruct images with 2, 4, 6, and 8 mpb for each patient. Visual and quantitative approaches were used to assess image quality and lesion detectability for each image. For image quality, (a) 3 readers independently scored subjective image quality on a 4-point scale and (b) a region-of-interest approach was used to obtain a quantitative estimate of image quality in terms of noise. For lesion detectability, (a) the readers independently counted the number of hypermetabolic lesions and (b) signal-to-noise ratio and contrast-to-noise ratio were computed in a region-of-interest approach. Moreover, the mean and maximal standardized uptake value (SUV mean and SUV max, respectively) of the hypermetabolic lesions was compared across all acquisition times. For image quality, subjective image quality significantly declined from 8 to 2 mpb (P <; 0.05), with the exception of the difference between 6 and 8 mpb. Image noise increased with shorter imaging duration, ranging from 13% on average in the 8-mpb scans to 23% in the 2-mpb scans (differences were statistically significant for 2 vs 6 mpb, 2 vs 8 mpb, and 4 vs 8 mpb; P <; 0.05). For lesion detectability, 39 hypermetabolic lesions were identified by consensus. There was no difference in detected lesions across all acquisition times. Signal-to-noise ratio and contrast-to-noise ratio were constantly high and did not differ significantly across the acquisition times. The SUV mean and SUV max did not differ significantly across all acquisition times. Positron emission tomography acquisition times on integrated PET/MRI do not need to exceed usual acquisition times on current PET/computed tomography scanners: Although the PET image quality suffers from short acquisition times, even a duration of 2 mpb permits sufficient lesion detection. Moreover, quantitative measures of tracer uptake are also reasonably precise at short acquisition times.

A false positive fluorodeoxyglucose lymphadenopathy in a patient with pulmonary carcinoid tumor and previous breast reconstruction after bilateral mastectomy

We present a case of a 60-year-old woman with a positive fluorodeoxyglucose integrated positron emission tomography and computed tomography (PET/TC) mammary chain lymphadenopathy and carcinoid tumor of the left lower lobe who had a previous bilateral mastectomy and breast reconstruction for breast cancer. She underwent a right muscle sparing mini-thoracotomy and mammary chain lymphadenectomy; the final histopathology showed granulomatous reaction to silicone.

Reply: Lung Cancer Diagnosis and Staging Centers

From the Authors: We thank Drs. Maturu, Agarwal, and Rossi for their interest in our article (1). Drs. Maturu and Agarwal question the cost effectiveness of endobronchial ultrasound–guided transbronchial needle aspiration (EBUS-TBNA) compared with standard bronchoscopy in the diagnosis of lung cancer. None of the patients included in our study had endobronchial disease, and we cannot agree with their statement that the vast majority of patients with lung cancer have abnormal endobronchial findings. Drs. Maturu and Agarwal also miss an important point regarding the utility of EBUS-TBNA in patients with lung cancer. Not only can EBUS-TBNA provide a lung cancer phenotype and genotype, but it also provides a highly accurate nodal stage, critical to determining the treatment options. EBUS-TBNA, therefore, provides considerable information in addition to that provided by bronchoscopy and may prevent the need for further investigations such as integrated positron emission tomography–computed tomography, endoscopic ultrasound–guided fine needle aspiration, and mediastinoscopy. We are currently investigating the clinical efficacy and cost effectiveness of EBUS-TBNA as an initial investigation after staging computed tomography scan in patients with suspected lung cancer (2). We agree with Dr. Rossi that the personalization of advanced non–small cell lung cancer (NSCLC) management has adjusted the spotlight onto tissue acquisition techniques and their interpretation. A paradox currently exists whereby patients with metastatic disease (in whom cancer phenotyping and genotyping is mandatory for best outcomes) have the smallest biopsies, whereas patients with considerably larger surgically resected specimens currently do not have systemic treatment tailored to their tumor. Dr. Rossi highlights the key role that the pathologist plays in deciding treatment options for patients with advanced NSCLC as well as the demands now placed on small biopsy samples. As well as the pathologist requiring more dedicated lung cancer expertise, the same may apply to pulmonologists. Evidence already exists that the presence of dedicated thoracic surgeons may result in better lung cancer outcomes (3). The number of centers using EBUS-TBNA as a diagnostic and staging tool continues to increase internationally. Although the learning curve to reach competency in the procedure may be short (4), the focus has been on procedure sensitivity, whereas the assessment of quality of samples generated has not yet been built into competency assessment. The centers included in our study are recognized for their expertise in lung cancer management, and it is unclear whether the results seen in our study may be generalizable to centers without specific expertise in lung cancer. Dr. Rossi calls for pathologists dedicated to lung cancer in each laboratory that receives lung cancer samples. However, given current progress and the prospect of further genetic targets in NSCLC reaching clinical utility in the very near future, perhaps the time has come to consider centers dedicated to lung cancer imaging and tissue acquisition as well as pathological diagnostics. This model may optimize the patient experience for lung cancer diagnosis and staging, raise standards of diagnostics to a more uniform level, be cost effective, and facilitate recruitment to clinical trials.

Measurement of primary tumor volume by PET–CT to evaluate risk of mediastinal nodal involvement in NSCLC patients with clinically negative N2 lymph nodes

AimThe study aimed to determine a prognostic value of primary tumor volume measured on the basis of integrated positron emission tomography–computerized tomography (PET–CT) in terms of mediastinal nodal metastases (N2) prediction in non-small-cell lung cancer (NSCLC) patients with PET–CT N2 negative lymph nodes. MethodsThe records of 70 potentially operable NSCLC patients treated with surgical resection were analyzed. All patients underwent diagnostic, preoperative PET–CT, which was the basis for tumor volume calculations as well as the evaluation of N2 nodes status. The logistic regression analysis was employed to determine correlation between mediastinal nodal involvement and volume of primary tumor (izoSUV2.5 volume), that is the volume of primary tumor inside SUV 2.5 line, tumor histology, location (peripheral vs. central), hilar node status. ResultsA statistically significant correlation between mediastinal node involvement and izoSUV2.5 volume, tumor histology, locations peripheral vs. central and hilar node status was found. The risk of mediastinal lymph node metastasis is 24% for tumor volume of 100cm3 and increases up to 40% for tumor volume of 360cm3. An increase of tumor volume by 1cm3 increases the risk of lymph node disease by 0.3%. Tumor histology adenocarcinoma vs. squamous cell carcinoma increases the risk of mediastinal lymph node involvement by 195%, location central vs. peripheral by 68% and hilar node involvement by 166%. ConclusionsThe study demonstrates that izoSUV2.5 volume of primary tumor may be considered as a prognostic factor in NSCLC patients, since it strongly correlates with mediastinal lymph node pathological status. This correlation is modified by primary tumor location, histology and hilar node involvement.

Fluorodeoxyglucose uptake in absence of CT abnormality on PET-CT: What is it?

The purpose of this article is to provide a pictorial review of the findings and interpretative pitfalls about focal fluorodeoxyglucose (FDG) uptake in the absence of corresponding computer tomography (CT) lesion or abnormality on an integrated positron emission tomography (PET)-CT. The integrated CT images in the PET-CT scanner allow correct co-registration and fused imaging of anatomical and functional data. On FDG PET-CT imaging, a real pathologic process often demonstrates abnormal uptake associated with a visible corresponding CT lesion or abnormality. When focal uptake is seen on PET imaging but no corresponding anatomic abnormality is visualized on the integrated CT, one should always be aware of possible mis-registration or mismatch of the PET and CT images due to the patient's respiratory or body motion. While most of the hot spots in the absence of corresponding anatomic abnormalities are artefactual or secondary to benign etiologies, some may represent small sized or early staged neoplasm or metastases, especially in the gastrointestinal tract and skeletons. Caution should be exercised to simply diagnose a pathology based on the presence of the uptake only, or exclude the disease based on the absence of anatomic abnormality.

The maximum standardized FDG uptake on PET-CT in patients with non-small cell lung cancer

BackgroundNon-small cell lung cancer (NSCLC) accounts for approximately 80% of new diagnoses of pulmonary carcinoma. This study investigated the correlation between 18 F-fluorodeoxyglucose uptake in computerized tomography integrated positron emission tomography and tumor size, lymph node metastasis, and distant metastasis in patients with NSCLC.MethodsThe records of 151 NSCLC patients (139 male, 12 female; mean age 59.60 years) were evaluated retrospectively.ResultsForty-one cases were adenocarcinomas; 45 squamous cell carcinomas; and 65 unspecified NSCLC. When the cases were categorized according to tumor size (group 1, ≤ 3 cm; group 2, > 3 and ≤ 5 cm; group 3, > 5 cm), the maximum standardized uptake value (SUVmax) was significantly lower in groups 1 and 2 compared with group 3 (p = 0.006 for each). Considering all cases, tumor SUVmax was not correlated with age, gender, or histopathological type. Lymph node metastases were pathologically proven in 24 cases: 24% of these were adenocarcinomas, 6% squamous cell carcinomas, and 16% unspecified NSCLC. Neither lymph node involvement nor distant metastases were correlated with tumor SUVmax, although lymph node size was positively correlated with lymph node SUVmax (r = 0.775; p < 0.001).ConclusionsSUVmax was significantly associated with tumor size, but not with distant metastases or lymph node involvement. Therefore, SUVmax on positron emission tomography is not predictive of the presence of metastases.

Surgical adhesive may cause false positives in integrated positron emission tomography and computed tomography after lung cancer resection

Surgical adhesives are frequently used after pulmonary resection to prevent or reduce pulmonary air leakages, since leakages may cause complications delaying the removal of chest drainage tubes and prolonging in-hospital stay. In this paper, we present 2 patients who underwent curative-intent pulmonary resection for non-small-cell lung carcinoma, in which the biological adhesive BioGlue(®) was used. Follow-up fluoro-2-deoxy-D-glucose positron emission tomography/computed tomographic (FDG-PET/CT) imaging revealed hypermetabolic pulmonary nodular lesions. Subsequent surgical exploration showed that the lesions were foreign body reactions to the bioadhesive. To our knowledge, this is the first study to examine false-positive follow-up FDG-PET/CT scans caused by the use of BioGlue(®) in pulmonary resection procedures.

Integrated Positron-Emission Tomography and Computed Tomography Manifestations of Cutaneous T-Cell Lymphoma

Integrated Positron-Emission Tomography and Computed Tomography Manifestations of Cutaneous T-Cell Lymphoma

PET/MRI: Challenges, solutions and perspectives

Already from the start of PET/CT integrating positron emission tomography (PET) and computed tomography (CT) in one instrument, there have been considerations how to combine PET and magnetic resonance imaging (MRI) so that their complementary abilities can be utilized in a single investigation. Since classical PET electronics fail in an even weak magnetic field and PET signal processing might disturb high-frequency signals of MRI, it soon became clear that new solutions had to be found to avoid mutual interferences. During the last fifteen years a number of different approaches towards PET/MRI for small animal imaging have been developed by research groups which together with their specific features are summarized in this review. Recently, PET/MRI for human imaging became available as well - this time by industrial initiatives. First some prototypes of BrainPET/MRI were developed followed by commercial products for simultaneous and non-simultaneous whole-body PET/MRI. Although only PET/MRI integrated in one scanner offers the full diversity of complementary multiparametric imaging, there are also promising applications of non-simultaneous sequential PET/MRI. While describing the present instrumentation for human PET/MRI, this review discusses the challenges and promises related to this new imaging technology.

Application of whole-body MRI to detect the recurrence of lung cancer

Although some therapeutics provide an opportunity for cure, recurrence is a major obstacle to achieve a complete remission for lung cancers. Therefore, precise assessment of lung cancers has been a task with challenge. In recent years, integration of positron emission tomography and computed tomography (PET–CT) and whole-body magnetic resonance imaging (WB-MRI) have been introduced as an alternative to standard multimodality imaging strategies and are now increasingly applied to various malignancies. However, there is little information on the surveillance capability of WB-MRI in patients with lung cancers. We aimed to investigate the clinical potential of WB-MRI as a novel surveillance modality after curative treatments for lung cancers, comparing it with PET–CT. Sixty two consecutive patients with lung malignancy who underwent both WB-MRI and PET–CT were selected to assess the recurrent malignant lesions. The clinical data including radiologic and pathologic findings were collected and analyzed retrospectively. On each lymph node station, the ability of WB-MRI to detect malignant lesions significantly correlated with that of PET–CT (γ=0.86; P<.01). The correlation coefficient ranged from 0.999 to 1 for assessing distant metastases from lung cancers by two modalities (P<.01). Based on the pathologic confirmation, both modalities showed an equivalent diagnostic accuracy (PET–CT: sensitivity 85.71%, specificity 47.27% versus WB-MRI: sensitivity 85.71%, specificity 56.25%). This study demonstrates the clinical potential of WB-MRI, together with PET–CT, as a novel surveillance modality for lung cancers after curative treatments.

Simultaneous PET–MRI in oncology: a solution looking for a problem?

With the recent development of integrated positron emission tomography–magnetic resonance imaging (PET–MRI) scanners, new possibilities for quantitative molecular imaging of cancer are realized. However, the practical advantages and potential clinical benefits of the ability to record PET and MRI data simultaneously must be balanced against the substantial costs and other requirements of such devices. In this review, we highlight several of the key areas where integrated PET–MRI measurements, obtained simultaneously, are anticipated to have a significant impact on clinical and/or research studies. These areas include the use of MR-based motion corrections and/or a priori anatomical information for improved reconstruction of PET data, improved arterial input function characterization for PET kinetic modeling, the use of dual-modality contrast agents, and patient comfort and practical convenience. For widespread acceptance, a compelling case could be made if the combination of quantitative MRI and specific PET biomarkers significantly improves our ability to assess tumor status and response to therapy, and some likely candidates are now emerging. We consider the relative advantages and disadvantages afforded by PET–MRI and summarize current opinions and evidence as to the likely value of PET–MRI in the management of cancer.

Evaluation of integrated positron emission tomography and computed tomography accuracy in detecting lymph node metastasis in patients with adenocarcinoma vs squamous cell carcinoma

The aim of our study was to analyze the specificity and sensitivity of integrated positron emission tomography and computed tomography (PET/CT) in detecting nodal metastasis according to histology (adenocarcinoma vs squamous cell carcinoma), and to identify the factors related to false-negative findings. A retrospective, single-institution review of 353 consecutive patients with suspected or pathologically proven, potentially resectable non-small-cell lung cancer (NSCLC) who had integrated PET/CT scanning at the same centre. Lymph node staging was pathologically confirmed on tissue specimens obtained at mediastinoscopy and/or thoracotomy. Statistical evaluation of PET/CT results was performed on a per-patient and per-nodal-station basis. A total of 2286 nodal stations (1643 mediastinal, 333 hilar and 310 intrapulmonary) were evaluated. Adenocarcinoma was the final diagnosis in 244 patients and squamous carcinoma in 109 patients. Nodes were positive for malignancy in 80 (32.8%) of 244 patients with adenocarcinoma (N1 = 31; N2 = 48 and N3 = 1) and in 32 (29.3%) of 109 with squamous carcinoma (N1 = 21 and N2 = 11). PET/CT in the adenocarcinoma group had a sensitivity, specificity and accuracy of 53.8, 91.5 and 79.1%, and in the squamous cell group, of 87.5, 81.8 and 83.5%, respectively in a per-patient analysis. In the analysis for N2 disease on a per-patient basis, the sensitivity, specificity and accuracy were 38.8, 97.4, and 85.7% for the adenocarcinoma group and 81.8, 91.8 and 90.8% in the squamous cell group. In the adenocarcinoma group, the mean diameter of false-negative lymph nodes was 7 mm (standard deviation [SD] ± 2.5 mm) compared with the diameter of true-positive lymph nodes of 12.5 (SD ± 4 mm; P < 0.00001). In the squamous cell group, the mean diameter of false-negative lymph nodes was 7.4 mm (SD ± 2.8 mm) compared with the diameter of true-positive lymph nodes of 14.7 (SD ± 6 mm; P < 0.005). In the adenocarcinoma group, false-negative lymph nodes were statistically correlated with the presence of vascular invasion and in the squamous cell group only with the maximum standardized uptake value (SUV(max)) < 5.4. The sensitivity of PET/CT in detecting nodal metastasis in patients with adenocarcinoma is too low to avoid any further invasive staging procedure. Ultrasound-guided needle biopsy or mediastinoscopy is still necessary in staging patients undergoing lung resection for adenocarcinoma.

Stage migration: results of lymph node dissection in the era of modern imaging and invasive staging for lung cancer†

Lung cancer staging has improved in recent years. Assuming that contemporary detailed preoperative staging may yield a lower rate of stage change after surgery, we were interested to determine the impact of our lymph node dissections performed at the time of surgical resection. We retrospectively analysed a database in our surgical unit that prospectively captured information on all patients assessed and treated for lung cancer. We reviewed the data on patients who underwent lung cancer surgery with curative intent between January 2006 and August 2010 so as to reflect contemporary practice. Prior to potentially curative treatment, patients systematically underwent staging computerized tomography (CT), integrated positron emission tomography (PET) with CT and brain imaging. Enlarged and/or PET-positive nodes were subject to invasive evaluation to establish the nodal status in line with the current guidelines. This was performed by needle aspiration or biopsy usually with ultrasound guidance, endobronchial or endo-oesophageal ultrasound with needle biopsy; mediastinoscopy; mediastinotomy; video-assisted or open surgery. Three hundred and twelve lung cancer resections were performed (a mean age of 68 years [range 42-86] and a male-to-female ratio of 1.14:1). Despite thorough preoperative evaluations, 25.3% of patients had a change in nodal status after lung resection and lymph node dissection; of which 20.8% of patients had a nodal status upstaging. Occult N2 disease was identified in 31 (9.9%) of 312 patients. Patients with cT1 tumours showed a nodal upstaging of 12.3% compared with 25.3% in cT2 tumours. There was no difference in the rate of N2 disease for different tumour histological types. Despite systematic preoperative staging, there continues to be a high rate of nodal status change following surgical resection and lymph node dissection. If considering non-surgical treatments for the early stage lung cancer, the impact of this discrepancy should be considered. If not, errors in prognosis and in determining correct adjuvant treatment may arise.

Simultaneous PET/MR body imaging in rats: initial experiences with an integrated PET/MRI scanner

We recently developed an integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) (iPET/MRI) scanner for small animals, which had relatively large field-of-view (FOV) covering up to the size of a rat body. The purpose of this study was to report results of simultaneous PET/MRI of a rat body using this scanner with some radiotracers. C-11-methionine (MET), F-18-fluorodeoxyglucose (FDG), or F-18-sodium fluoride (NaF) was injected as a radiotracer for PET portion in addition to gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid, a hepatobiliary contrast agent, for MRI portion. Simultaneous PET/MRI was performed in normal rats. PET, MRI, and co-registered fusion images were evaluated regarding image quality and feasibility for rat imaging studies. MET uptake was clearly shown in the liver and pancreas, which was confirmed with magnetic resonance (MR) and fused PET/MR images. PET/MR images depicted intense FDG uptake in the brain, Harderian glands, and myocardium. NaF uptake was observed in all bones and joints within FOV, except in ribs, which was well recognized with the help of MR and fused PET/MR images. This study demonstrated that simultaneous PET/MRI with an integrated dual-modality molecular imaging scanner was a feasible technique for imaging studies targeting on a rat body. However, further developments including attenuation correction methods are required to use this technique routinely in rat imaging studies.