Combined PET-CT Research Articles

Imaging of solitary pulmonary nodule-a clinical review.

Current widespread use of cross-sectional imaging has led to exponential rise in detection of solitary pulmonary nodules (SPNs). Whilst large numbers of these are benign 'incidentalomas', lung cancers presenting as SPNs are often early disease, which have good prognosis. Therefore, there is rising demand and expectation for more accurate, non-invasive, diagnostic tests to characterize SPNs, aiming to avoid missed or delayed diagnosis of lung cancer. There are wide differential diagnoses of benign and malignant lesions that manifest as SPNs. On conventional imaging, the morphological features supporting benignity include stable small nodule size, smooth demarcated margins, and calcifications. Lack of significant contrast enhancement is also more suggestive of benign nodules. With improved understanding of tumor biology, for instance neo-vascularization and increased vascular permeability, imaging techniques such as dynamic contrast-enhanced computed tomography (CT) provide details on contrast uptake and wash-out kinetics, which is more closely reflecting the physiological and pathological phenomena. Positron emission tomography (PET) using 18fluorine-fluoro-deoxyglucose ((18)F-FDG) is a well-established functional imaging technique, for which one of the most common indications is differentiating between benign and malignant SPNs. Combined PET-CT integrates the anatomical, morphological and metabolic aspects in a single examination, improving overall diagnostic accuracy. Semi-quantitative analysis in FDG-PET imaging is based on measurement of maximum standardized uptake values (SUVmax). SUVmax analysis may become more useful as an assessment of tumor biology in future risk stratification models for cancers. Dual-time point FDG-PET imaging, dual-energy CT, perfusion CT, magnetic resonance (MR) imaging using dynamic contrast enhancement or diffusion-weighted imaging (DWI) techniques, are among the growing armamentarium for diagnostic imaging of SPNs. Provided there is no unacceptably high procedural or operative risk, tissue diagnosis by resection or percutaneous biopsy of SPN should be advocated in those patients identified as at moderate or high risk of malignancy, based on clinical stratification.

High-resolution imaging of pulmonary ventilation and perfusion with 68Ga-VQ respiratory gated (4-D) PET/CT

Our group has previously reported on the use of (68)Ga-ventilation/perfusion (VQ) PET/CT scanning for the diagnosis of pulmonary embolism. We describe here the acquisition methodology for (68)Ga-VQ respiratory gated (4-D) PET/CT and the effects of respiratory motion on image coregistration in VQ scanning. A prospective study was performed in 15 patients with non-small-cell lung cancer. 4-D PET and 4-D CT images were acquired using an infrared marker on the patient's abdomen as a surrogate for breathing motion following inhalation of Galligas and intravenous administration of (68)Ga-macroaggregated albumin. Images were reconstructed with phase-matched attenuation correction. The lungs were contoured on CT and PET VQ images during free-breathing (FB) and at maximum inspiration (Insp) and expiration (Exp). The similarity between PET and CT volumes was measured using the Dice coefficient (DC) comparing the following groups; (1) FB-PET/CT, (2) InspPET/InspCT, (3) ExpPET/Exp CT, and (4) FB-PET/AveCT. A repeated measures one-way ANOVA with multiple comparison Tukey tests were performed to evaluate any difference between the groups. Diaphragmatic motion in the superior-inferior direction on the 4-D CT scan was also measured. 4-D VQ scanning was successful in all patients without additional acquisition time compared to the nongated technique. The highest volume overlap was between ExpPET and ExpCT and between FB-PET and AveCT with a DC of 0.82 and 0.80 for ventilation and perfusion, respectively. This was significantly better than the DC comparing the other groups (0.78-0.79, p < 0.05). These values agreed with a visual inspection of the images with improved image coregistration around the lung bases. The diaphragmatic motion during the 4-D CT scan was highly variable with a range of 0.4-3.4cm (SD 0.81cm) in the right lung and 0-2.8cm (SD 0.83cm) in the left lung. Right-sided diaphragmatic nerve palsy was observed in 3 of 15 patients. (68)Ga-VQ 4-D PET/CT is feasible and the blurring caused by respiratory motion is well corrected with 4-D acquisition, which principally reduces artefact at the lung bases. The images with the highest spatial overlap were the combined expiration phase or FB PET and average CT. With higher resolution than SPECT/CT, the PET/CT technique has a broad range of potential clinical applications including diagnostic algorithms for patients with suspected pulmonary embolism, preoperative evaluation of regional lung function and improving assessment or understanding of pulmonary physiology in the vast range of pulmonary diseases.

Application and value of preoperative staging in gastric cancer

A more differentiated therapy regimen for gastric carcinoma requires more precise preoperative staging. In patients with early gastric cancer (EGC), especially mucosa, endoscopic resection (ER) should be performed to avoid unnecessary surgical procedures. To achieve R0 resection for locally-advanced gastric cancer (AGC), neoadjuvant treatments have been investigated. Clinical staging of gastric cancer has been greatly improved by advance in imaging techniques such as endoscopic ultrasonography (EUS), transabdominal ultrasonography (TAUS), multi-slice spiral CT (MSCT), magnetic resonance imaging (MRI), positron emission tomography (PET), combined PET-CT scans, and laparoscopic staging. This review is to summarize the clinical application and the value of preoperative staging in gastric cancer.

Whole‐body MRI with diffusion‐weighted sequences compared with 18 FDG PET‐CT, CT and superficial lymph node ultrasonography in the staging of advanced cutaneous melanoma: a prospective study

The aim of our study was to compare the diagnostic performances of non-radiating whole-body magnetic resonance imaging (wbMRI), either volumetric, with Volumetric interpolated breath-hold examination (VIBE) or metabolic, with diffusion-weighted sequences (wbMRI), with classical irradiating techniques such as PET-CT, CT and with lymph node ultrasonography (US) for the staging of advanced melanoma. Thirty-seven melanoma AJCC stage IV patients were prospectively included. All images were independently interpreted without prior knowledge of the results of studies performed with concurrent techniques, and all imaging techniques were scheduled within a mean interval of 7days. The overall and site-specific diagnosis performances of each imaging modality were studied, as well as the interest of combined MRI VIBE and diffusion sequences. The number of visceral or lymph node metastases spotted was, respectively, 218, with 125 metastases for wbMRI, 191/103 for PET-CT, 209/115 for CT and 33/13 for lymph node US. No statistically significant difference (P<0.05) of overall diagnostic performances between wbMRI (Se 84%, Sp 87.1%, PPV 89.8%, NPV 80.2%) and PET-CT (Se 79.8%, Sp 93.1%, PPV 93.2%, NPV 79.4%) was observed. No statistically significant difference was found between wbMRI and PET-CT with two channels for CT with respect to different metastatic sites. Compared with the CT, wbMRI had significantly better overall specificity (P=0.0011) and PPV (P=0.02). For lung exploration, sensitivity of wbMRI (51.6%) was inferior to CT (71.4%). To detect superficial metastatic lymph nodes, wbMRI and US both showed high diagnostic accuracy with no statistically significant difference. Intra-observer agreement was almost perfect for all imaging modalities considering the overall staging. Inter-observer agreement for wbMRI and diffusion alone was almost perfect except for bone and lymphatic sites. Overall diagnostic performance of diffusion alone was significantly inferior to those of combined VIBE and diffusion sequences. Whole-body MRI, using diffusion weighted sequences, was a reliable non-radiating imaging for staging of melanoma and offers the same diagnostic performances than combined CT, PET-CT and lymph node US.

Primary Cerebral Radiotherapy-Induced Rhabdomyosarcoma: Treatment with Intraoperative Carmustine Implants

Introduction: Primary cerebral rhabdomyosarcomas (cRMS) are extremely rare, with only 41 cases reported in the literature. Survival of patients with localized cRMS is 70% after 5 years but not in the case of intracranial neoplasms, where survival rarely exceeds 10 months. Case report: A 10-year-old female patient with a history of acute lymphoblastic leukemia (ALL) and holocranial radiotherapy (RT) 6 years ago, referred after partial surgical resection of a left parietal lesion, diagnosed as an embryonal tumor with mixed neuronal-glial differentiation (WHO grade IV). A second operation was performed for complete resection and placement of intracavitary chemotherapy (carmustine). The pathology revealed a high-grade undifferentiated neoplasm positive for myogenin and desmin that was compatible with cRMS. In the immunohistochemistry study, the neoplasm was positive for vimentin, myogenin, and desmin, as is characteristic of cRMS, and negative for synaptophysin and enolase, ruling out primitive neuroectodermal embriogenic tumor (PNET). Given a diagnosis of cRMS, a combined thoracoabdominal PET-CT scan was performed without finding other primary lesions and a bone marrow study was also performed without observing abnormalities. Consequently, the diagnosis was established as primary cRMS. Discussion: Among the long-term sequelae of radiotherapy, neurocognitive disorders, brain disorders such as leukomalacia, vascular diseases, or secondary tumors, ranging from benign lesions such as meningiomas to more aggressive lesions such as ependymomas, which are high-grade gliomas, are described. In the brain MRI, our patient showed a radiotherapy-induced periventricular leukomalacia and a malignant lesion: a cRMS. The use of carmustine in this disease may facilitate local control.

Whole-body MR or PET-CT?

Breast cancer is the most frequent malignancy and most common cause of cancer-related death in women worldwide with approximately 500,000 deaths each year [1]. Approximately 10–20% of all patients diagnosed with breast cancer will develop tumor recurrence at some time within the course of their disease. Therefore, early diagnosis and accurate restaging of recurrent breast cancer is important to define appropriate therapeutic strategies or to identify patients with limited disease who potentially could benefit from curative treatment. The basic strategy in the follow-up of breast cancer to date consists of regular mammography and clinical examinations as well as symptomorientated multi-modal imaging strategies [2]. This procedure by large is based on assumptions from studies performed in the early 90’s, that an intensified after-care does not necessarily correlate with an increased survival benefit [3,4]. Unfortunately, this approach mainly comprises modalities with known poor sensitivity (e.g. chest radiographs), examinations with examinerdependent variation of sensitivity (e.g. abdominal ultrasound) or procedures with limited specificity, like bone scintigraphy [5, 6]. In the last 10 years numerous promising concepts have been developed for the therapy of metastasized breast cancer, including hormonal drugs and immune therapy, which indicate an improvement in patients’ progression-free survival [6–8]. New surgical and interventional techniques for the management of limited disease have demonstrated its effectiveness and reported promising survival rates [8,9]. Against this background, whole-body imaging modalities, such as fluorodeoxyglucose positron emission tomography (FDG-PET)-CT or whole body-MRI (WB-MRI) appear as new promising tools to detect tumor recurrence with high accuracy and to provide more effective therapeutic strategies to the patient. It has been reported that whole-body fluorodeoxyglucose (FDG)positron emission tomography (PET) is of clinical value in the search for breast cancer metastases, especially when suggested by the presence of clinical symptoms or by a progressive increase in biochemical markers [9,10]. The combination of metabolic data from PET with the detailed anatomical information of multi-slice computed tomography as dual-modality scanners has markedly increased lesion localization and diagnostic accuracy compared to both modalities as standalone applications [11,12]. Recently, combined PET-CT has been introduced as a whole-body imaging modality for screening of patients with suspicion of recurrent breast cancer, indicating an improved restaging accuracy and possible impact on therapy [13].

39. Patient selection and results of surgical treatment

Oesophageal cancer is preferably treated by surgical resection with curative intent. Mainstay of oncological surgery is a microscopically radical resection. Endoscopic ultrasonography, CT-scanning and bronchoscopy are essential diagnostic tools for exclusion of T4-tumours. Distant dissemination can be detected by combined PET-CT scanning.

Age and dose-limited PET-CT scan regime in lymphoma: between the devil and the deep blue sea?

In this study the authors speculate about hypothetical effective-dose (E) reduction through limiting post-chemotherapy PET-CT scanning to lymphoma sites previously identified on pre-treatment CT. E reductions/scan time savings are compared between post-treatment standard and theoretically limited PET-CT scans. The influence of patient age with E savings and associated clinical implication for 100 subjects are discussed. The greatest E theoretical savings of 52 and 32% for the CT contribution and combined PET-CT, respectively, were seen in patients <18 y old using limited scans in this study, with a potential mean time saving of 16 min per patient across the entire cohort. However, the limited PET-CT regime here missed a 1% rate of unexpected cancer that standard PET-CT recorded. The authors recommend performing larger scale multi-centre studies comparing PET-CT pre- and post-chemotherapy to establish full clinical efficacy of this method.

A Novel Medical Image Registration Algorithm for Combined PET-CT Scanners Based on Improved Mutual Information of Feature Points

Accurate registration of PET and CT images is an important component in oncology, so we aim to develop an automated registration algorithm for PET and CT images acquired by different system. These two modalities offer affluent complementary information: CT provides specificity to anatomic findings, and PET provides precise localization of metabolic activity. In this paper, we proposed an improved registration method that can accurately align PET and CT images. This registration algorithm includes two stages. The first stage is to deform PET image based on B-Spline Free Form Deformations (FFD). It is consists of three independent steps. After the feature points of PET and CT images have been extracted in the preprocessing step. As a next step, the PET image is deformed by B-Spline Free Form Deformations (FFD) with feature points of CT images. The second stage is to register PET and CT images based on Mutual Information (MI) of feature points combined with Particle Swarm Optimization (PSO) algorithm and Powell algorithm that are used to search the optimal registration parameters.

Pitfalls in PET/CT imaging

PET with 2-[fluorine 18] fluoro-2-deoxy-d-glucose (FDG), has been a clinical tool for the evaluation of various cancers providing valuable metabolic information clinically helpful in the diagnosis, initial staging, therapy monitoring and restaging. However, FDG is not specific for neoplastic processes. Unless anatomic correlation is available to delineate normal structures, pathologic sites of FDG accumulation can easily be confused with normal physiological uptake, leading to false-positive or false-negative findings. Coregistration of PET scans (functional and morphologic information) with computed tomographic (CT) scans (anatomic information) using a combined PET-CT scanner improves the overall sensitivity and specificity of information provided by PET or CT alone. In this paper, we discuss the probable causes of false negative images and pitfalls due to technical reasons, inflammatory processes or benign lesions as well as the utility of PET-CT in differentiating malignant from inflammatory and benign processes, since in some cases such differentiation cannot be made, with certainty, using FDG PET alone.

Preoperative staging of suspicious pulmonary nodules with combined PET-CT: Concordance of clinical and pathological staging

Preoperative staging of suspicious pulmonary nodules with combined PET-CT: Concordance of clinical and pathological staging

Does positron emission tomography offer prognostic information in malignant pleural mesothelioma?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether positron emission tomography is useful in the diagnosis and prognosis of malignant pleural mesothelioma (MPM). Altogether 136 papers were found using the reported search, of which 15 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that fluorodeoxyglucose-positron emission tomography (FDG-PET) accurately differentiates benign from malignant pleural disease, helps detect recurrence and provides prognostic information in terms of staging, survival and mortality. Eleven studies evaluated the role of FDG-PET in the diagnosis and prognosis of MPM. Malignant disease had a higher standardised uptake value (SUV) (6.5 ± 3.4 vs. 0.8 ± 0.6; P < 0.001) than benign pleural disease. Shorter median survival (9.7 vs. 21 months; P = 0.02) was associated with high SUV (>10) than low SUV (<10). PET accurately upstaged 13% and downstaged 27% of cases initially staged with computed tomography (CT). In patients undergoing chemotherapy, higher total glycolytic volume led to a lower median survival (4.9 vs. 11.5 months; P = 0.09), while a decline in FDG uptake was associated with a longer time to tumour progression (14 vs. 7 months; P = 0.02). Four studies observed the role of FDG-PET-CT in the diagnosis and prognosis of MPM. SUV was found to be higher in MPM compared to benign pleural disease (6.5 vs. 0.8; P < 0.001). A higher SUV(max) was observed in primary pleural lesions of metastatic (7.1 vs. 4.7; P = 0.003) compared to non-metastatic disease. Patients who underwent surgery had equivalent survival to those excluded based on scan results (20 vs. 12 months; P = 0.3813). One study compared the utility of PET and PET-CT in the diagnosis and prognosis of mesothelioma. PET-CT was found to be more accurate than PET in terms of staging (P < 0.05) disease. Overall, PET accurately diagnoses MPM, predicts survival and disease recurrence. It can guide further management by predicting the response to chemotherapy and excluding surgery in patients with extrathoracic disease. Combined PET-CT has additional benefits in accurately staging disease.

Functional imaging of renal cell carcinoma

The incidence of early and advanced-stage renal cell carcinoma (RCC) is increasing. Methods of diagnosing, staging and evaluating tumor burden that are more accurate and reliable than the currently available options are needed in order to identify RCC at a stage at which it is curable and to accurately determine the response to treatment. Functional imaging, particularly with combined PET-CT, might improve accuracy of detection and provide essential information that has been unavailable to date. This approach is against a background in which targeted therapies for metastatic RCC have entered clinical practice in the past few years, further highlighting the importance of accurate imaging for patient selection and for monitoring response to treatment. We outline the current clinical status of functional imaging in RCC using PET-CT, which allows simultaneous capture and co-registration of functional and anatomical data. New radiotracers and approaches-including radiolabeled monoclonal antibodies and imaging of tumor hypoxia-are touched on, and areas of future research discussed.

The Evolution of Whole-Body Imaging

This article reviews the evolution of whole-body imaging, discussing the history and development of radiography, nuclear medicine, computed tomography (CT), positron emission tomography (PET), combined PET-CT, and magnetic resonance imaging. The obstacles hindering progress toward whole-body imaging using each of these modalities, and the technical advances that were developed to overcome them, are reviewed. The effectiveness and the limitations of whole-body imaging with each of these techniques are also briefly discussed.

Preoperative Staging of Lung Cancer with Combined PET–CT

Preoperative Staging of Lung Cancer with Combined PET–CT

Preoperative Staging of Lung Cancer with Combined PET–CT

Preoperative Staging of Lung Cancer with Combined PET–CT

F18]-fluoroethylcholine combined in-line PET-CT scan for detection of lymph-node metastasis in high risk prostate cancer patients prior to radical prostatectomy: Preliminary results from a prospective histology-based study

PurposeTo evaluate the diagnostic potential of PET/CT using ([F18]fluorethylcholine (FEC) for lymph node (LN) staging in high risk prostate cancer (PCa) patients prior to radical prostatectomy (RP). Patients and methodsTwenty patients with localised PCa and ⩾20% LN risk according to a published nomogram were prospectively enrolled. FEC PET/CT was done minimum 14d after prostate biopsy. Afterwards, open RP and extended pelvic LN dissection (ePLND) were performed. Clinical stage, Prostate Specific Antigen (PSA) and biopsy Gleason Grading were assessed and histopathological evaluation of the RP-specimens and dissected LN has been performed. The results from PET/CT were compared with LN metastasis according to their anatomical site. ResultsOverall, 285 LN have been removed with a mean number of 15 nodes per patient (7–26). Of the 20 patients, 9 men were LN positive (45%), which corresponds to 31 positive LN with a mean size of 7mm (0.8–12mm). Dissection of the obturator fossa, external iliac artery/vein and internal iliac artery/vein revealed 36%, 48% and 16% of positive LN, respectively. FEC PET/CT did not detect one single positive LN, thus was false-negative in 31 metastasis and true negative in 254 LN. ConclusionBased on our results which confirmed experience from the previous studies, FEC PET/CT scan did not prove to be useful for LN staging in localised PCa prior to treatment and should thus not be applied if clinically occult metastatic disease is suspected.

Preoperative Staging of Lung Cancer with Combined PET–CT

Fast and accurate staging is essential for choosing treatment for non-small-cell lung cancer (NSCLC). The purpose of this randomized study was to evaluate the clinical effect of combined positron-emission tomography and computed tomography (PET-CT) on preoperative staging of NSCLC. We randomly assigned patients who were referred for preoperative staging of NSCLC to either conventional staging plus PET-CT or conventional staging alone. Patients were followed until death or for at least 12 months. The primary end point was the number of futile thoracotomies, defined as any one of the following: a thoracotomy with the finding of pathologically confirmed mediastinal lymph-node involvement (stage IIIA [N2]), stage IIIB or stage IV disease, or a benign lung lesion; an exploratory thoracotomy; or a thoracotomy in a patient who had recurrent disease or death from any cause within 1 year after randomization. From January 2002 through February 2007, we randomly assigned 98 patients to the PET-CT group and 91 to the conventional-staging group. Mediastinoscopy was performed in 94% of the patients. After PET-CT, 38 patients were classified as having inoperable NSCLC, and after conventional staging, 18 patients were classified thus. Sixty patients in the PET-CT group and 73 in the conventional-staging group underwent thoracotomy (P=0.004). Among these thoracotomies, 21 in the PET-CT group and 38 in the conventional-staging group were futile (P=0.05). The number of justified thoracotomies and survival were similar in the two groups. The use of PET-CT for preoperative staging of NSCLC reduced both the total number of thoracotomies and the number of futile thoracotomies but did not affect overall mortality. (ClinicalTrials.gov number, NCT00867412.)

Molekulare Kardiale PET jenseits der FDG-Vitalitätsdiagnostik

Molecular cardiac non F-18-FDG PET is currently based on perfusion imaging. It is of excellent diagnostic accuracy to detect coronary artery disease (CAD) and superior to perfusion SPECT. There is also evidence for its incremental prognostic value. The unique feature of PET to measure myocardial perfusion in absolute terms and in short time periods define its impact on cardiac imaging enabling both the evaluation of early changes in CAD and the accurate characterization of multivessel disease. Currently, all available PET perfusion tracers in Europe are cyclotron products. Rb-82, a generator product, is the most frequently employed perfusion tracer in the United States and cyclotrone independent. This tracer has the potential to become an alternative in Europe soon. Nowadays, PET systems are manufactured as hybrid PET-CT scanners. In oncology, hybrid imaging revealed, that the combination of functional and morphological imaging is superior to the single components. In cardiology, the integration of perfusion PET imaging with CT calcium scoring and CT anatomy of the coronary arteries represents a similar constellation. Atherosclerotic plaque evaluation by combined PET-CT technique will be one of the most promising future applications with a potential immense impact on prophylaxis, diagnosis and therapy of CAD in the future.

PET-TC en oncología: la importancia de un equipo multidisciplinar

Before the advent of combined PET-CT in 2000, CT and FDG-PET used separately had become the imaging techniques of choice for the management of oncologic patients. Integrating these two modalities into a single scanner confers diverse clinical advantages. There is less confusion over nonmalignant FDG uptake caused by inflammatory foci or due to variation in normal physiologic uptake among different tissues, such as brown fat or muscles, because CT enables the anatomic location to be determined more accurately. In addition, PET-CT enables improved localization of malignant lesions, better follow-up of the response to treatment, and improved targeting for biopsy and radiotherapy. PET-CT also improves the detection of non-FDG-avid tumors that would not be evident on a PET study alone. PET-CT should be the only procedure in most oncologic patients, obviating further CT examinations, which is particularly important in children. Close collaboration between specialists in nuclear medicine and radiologists is essential to obtain the maximum benefit of combined PET-CT scans. This collaboration is also necessary in other hybrid systems, such as SPECT-CT or PET-MRI. In oncologic patients, it is important to ensure that maximum diagnostic yield of PET-CT is reached; this can only be accomplished in diagnostic imaging departments that enable close collaboration between professionals of different specialties.