Commonly used imaging techniques for diagnosis and staging

Clinical Application of 18F-FDG-PET Quantification in Hematological Malignancies: Emphasizing Multiple Myeloma, Lymphoma and Chronic Lymphocytic Leukemia

Most hematological malignancies display heightened glycolytic activity, leading to their detectability through 18F-FDG-PET imaging. PET quantification enables the extraction of metabolic information from tumors. Among various PET measurements, maximum standardized uptake value (SUVmax), which indicates the highest value of 18F-FDG uptake within the tumor, has emerged as the commonly used parameter in clinical oncology. This is because of SUVmax ease of calculation using most available commercial workstations, as well as its simplicity and independence from observer interpretation. Nonetheless, SUVmax represents the increase in activity within a specific small area, which may not fully capture the overall tumor uptake. Volumetric PET parameters have been identified as a potential solution to overcome certain limitations associated with SUVmax. However, these parameters are influenced by the low spatial resolution of PET when assessing small lesions. Another challenge is the high number of lesions observed in some patients, leading to a time-consuming process for evaluating all focal lesions. Some institutions recently have started advocating for CT-based segmentation as a method for measuring radiotracer uptake in the bone marrow and overall bone of the patients. This review article aims to provide insights into clinical application of PET quantification specifically focusing on 3 major hematologic malignancies: multiple myeloma, lymphoma, and chronic lymphocytic leukemia.

Drug-Loaded Acoustic Nanodroplet for Dual-Imaging Guided Highly Efficient Chemotherapy Against Nasopharyngeal Carcinoma

Background

Chemotherapy is an important approach to treating nasopharyngeal carcinoma (NPC). Unfortunately, the lack of selectivity, insufficient tumor accumulation, uneven tumor distribution and severe systemic toxicity lead to the unsatisfactory performance of these drugs. While a more precise drug delivery, on-demand drug release, and deep diffusion of drugs (homogeneous distribution of drugs in the tumor) could improve the application, they remain challenging. Chemotherapeutic drug-loaded acoustic nanodroplet with dual-imaging capacity is expected to solve these problems.

Methods

Folate (Fa)-modified and doxorubicin (Dox)-loaded acoustic poly (lactic-co-glycolic acid) (PLGA), low intensity focused ultrasound (LIFU)-responsive perfluoropentane (PFP) and Fe₃O₄ nanoparticles (designated as Fa-Fe@P-PFP-Dox) were integrated by a double-emulsion method. After the synthesis, the LIFU-triggered acoustic droplet vaporization (ADV) effect, LIFU-triggered drug release, cell targeting capability, in vitro cell-killing effects, biodistribution, PA/MR dual imaging (PA: photoacoustic; MR: magnetic resonance), LIFU-augmented Dox distribution in tumors and chemotherapeutic efficacy of Fa-Fe@P-PFP-Dox were investigated.

Results

The distribution of these drug-loaded nanodroplets was clearly monitored via PA/MR dual imaging. Upon LIFU irradiation, PFP within the Fa-Fe@P-PFP-Dox nanodroplets underwent ADV, which led to the release of Dox and promoted the deep penetration of Dox in tumor tissue, eventually achieving highly efficient chemotherapy against NPC. As a result, LIFU-triggered chemotherapy exerted a highly efficient therapeutic effect with a tumor inhibition rate of 74.24 ± 7.95%.

Conclusion

Fa-modified and drug-loaded acoustic nanodroplets have been successfully constructed for dual-imaging guided highly efficient chemotherapy against NPC. This novel tumor drug delivery method is expected to provide an efficient, visualized, and precise personalized treatment method for NPC patients with minimal side effects.

Tumor‐targeted fluorescence labeling systems for cancer diagnosis and treatment

Conventional imaging techniques are available for clinical identification of tumor sites. However, detecting metastatic tumor cells that are spreading from primary tumor sites using conventional imaging techniques remains difficult. In contrast, fluorescence‐based labeling systems are useful tools for detecting tumor cells at the single‐cell level in cancer research. The ability to detect fluorescent‐labeled tumor cells enables investigations of the biodistribution of tumor cells for the diagnosis and treatment of cancer. For example, the presence of fluorescent tumor cells in the peripheral blood of cancer patients is a predictive biomarker for early diagnosis of distant metastasis. The elimination of fluorescent tumor cells without damaging normal tissues is ideal for minimally invasive treatment of cancer. To capture fluorescent tumor cells within normal tissues, however, tumor‐specific activated target molecules are needed. This review focuses on recent advances in tumor‐targeted fluorescence labeling systems, in which indirect reporter labeling using tumor‐specific promoters is applied to fluorescence labeling of tumor cells for the diagnosis and treatment of cancer. Telomerase promoter‐dependent fluorescence labeling using replication‐competent viral vectors produces fluorescent proteins that can be used to detect and eliminate telomerase‐positive tumor cells. Tissue‐specific promoter‐dependent fluorescence labeling enables identification of specific tumor cells. Vimentin promoter‐dependent fluorescence labeling is a useful tool for identifying tumor cells that undergo epithelial–mesenchymal transition (EMT). The evaluation of tumor cells undergoing EMT is important for accurately assessing metastatic potential. Thus, tumor‐targeted fluorescence labeling systems represent novel platforms that enable the capture of tumor cells for the diagnosis and treatment of cancer.

Mapping the cancer imaging research landscape: which cancers are more and which cancers are less frequently investigated?

OBJECTIVE

To investigate the proportion of published imaging studies relative to incidence and mortality rate per cancer type.

METHODS

From a random sample of 2500 articles published in 2019 by the top 25 imaging-related journals, we included cancer imaging studies. The publication-to-incidence and publication-to-mortality ratios (defined as the publication rate divided by the proportional incidence and mortality rate, respectively) were calculated per cancer type. Ratios >1 indicate a higher publication rate compared to the relative incidence or mortality rate of a specific cancer. Ratios <1 indicate a lower publication rate compared to the relative incidence or mortality rate of a specific cancer.

RESULTS

620 original cancer imaging studies were included. Female breast cancer (20.2%), prostate cancer (13.0%), liver cancer (12.9%), lung cancer (8.8%), and cancers in the central nervous system (8.1%) comprised the top 5 of cancers investigated. Cancers in the central nervous system and liver had publication-to-incidence ratios >2, whereas nonmelanoma of the skin, leukemia, stomach cancer, and laryngeal cancer had publication-to-incidence ratios <0.2. Cancers in the prostate, central nervous system, female breast, and kidney had publication-to-mortality ratios >2, whereas esophageal cancer, stomach cancer, laryngeal cancer, and leukemia had publication-to-mortality ratios <0.2.

CONCLUSION

This overview of published cancer imaging research may be informative and useful to all stakeholders in the field of cancer imaging. The potential causes of disproportionality between the publication rate vs. incidence and mortality rates of some cancer types are multifactorial and need to be further elucidated.

Synthesis, Radiolabeling, and Biological Evaluation of the trans-Stereoisomers of 1-Amino-3-(fluoro-18F)-4-fluorocyclopentane-1-carboxylic Acid as PET Imaging Agents

The enantiomeric non-natural cyclic amino acids (3R,4R)-1-amino-3-fluoro-4-(fluoro-¹⁸F)cyclopentane-1-carboxylic acid and (3S,4S)-1-amino-3-fluoro-4-(fluoro-¹⁸F)cyclopentane-1-carboxylic acid ([ ¹⁸ F]5) have been prepared as a racemic mixture in 1.3% decay corrected radiochemical yield and in greater than 99% radiochemical purity. [ ¹⁸ F]5 is transported primarily via system L with some transport occurring via system ASC, as assessed in rat 9L gliosarcoma, human U87 ΔEGFR glioblastoma, and human DU145 androgen-independent prostate carcinoma tumor cells. In rats bearing intracranial 9L gliosarcoma, [ ¹⁸ F]5 gave tumor to contralateral brain tissue ratios of up to 2.8. Biodistribution studies in healthy rats demonstrated that bladder accumulation is delayed until 10 min postinjection.

Synthesis, Radiolabeling, and Biological Evaluation of the cis Stereoisomers of 1-Amino-3-Fluoro-4-(fluoro-18F)Cyclopentane-1-Carboxylic Acid as PET Imaging Agents

The non-natural cyclic amino acids (1S,3R,4S)-1-amino-3-fluoro-4-(fluoro-¹⁸F)cyclopentane-1-carboxylic acid ([¹⁸F]9) and (1S,3S,4R)-1-amino-3-fluoro-4-(fluoro-¹⁸F)cyclopentane-1-carboxylic acid ([¹⁸F]28) have been prepared in 10 and 1.7% decay corrected radiochemical yield, respectively, and in greater than 99% radiochemical purity. Cell assays in rat 9L gliosarcoma, human U87 ΔEGFR glioblastoma, and human DU145 androgen-independent prostate carcinoma tumor cells indicated that both compounds are substrates for amino acid transport primarily by system L, with some transport taking place via system ASC. In rats with 9L gliosarcoma, [¹⁸F]9 and [¹⁸F]28 provided high tumor to normal brain tissue ratios, with maximal ratios of 3.5 and 4.1, respectively. Biodistribution studies in healthy rats confirmed that both compounds are BBB permeable and that bladder accumulation is low until at least 5 min post injection.

Temporal subtraction of low-dose and relatively thick-slice CT images with large deformation diffeomorphic metric mapping and adaptive voxel matching for detection of bone metastases: A STARD-compliant article

To evaluate the improvement of radiologist performance in detecting bone metastases at follow up low-dose computed tomography (CT) by using a temporal subtraction (TS) technique based on an advanced nonrigid image registration algorithm.Twelve patients with bone metastases (males, 5; females, 7; mean age, 64.8 ± 7.6 years; range 51-81 years) and 12 control patients without bone metastases (males, 5; females, 7; mean age, 64.8 ± 7.6 years; 51-81 years) were included, who underwent initial and follow-up CT examinations between December 2005 and July 2016. Initial CT images were registered to follow-up CT images by the algorithm, and TS images were created. Three radiologists independently assessed the bone metastases with and without the TS images. The reader averaged jackknife alternative free-response receiver operating characteristics figure of merit was used to compare the diagnostic accuracy.The reader-averaged values of the jackknife alternative free-response receiver operating characteristics figures of merit (θ) significantly improved from 0.687 for the readout without TS and 0.803 for the readout with TS (P value = .031. F statistic = 5.24). The changes in the absolute value of CT attenuations in true-positive lesions were significantly larger than those in false-negative lesions (P < .001). Using TS, segment-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the readout with TS were 66.7%, 98.9%, 94.4%, 90.9%, and 94.8%, respectively.The TS images can significantly improve the radiologist's performance in the detection of bone metastases on low-dose and relatively thick-slice CT.

Gd-/CuS-Loaded Functional Nanogels for MR/PA Imaging-Guided Tumor-Targeted Photothermal Therapy

The second near-infrared (NIR-II, 1000-1700 nm) light-based diagnosis and therapy have received extensive attention for neoplastic disease treatments because of the fact that light in the NIR-II window possesses less photon scattering along with deeper tissue penetration than that in the NIR-I (700-950 nm) window. Herein, we present a Gd- and copper sulfide (CuS)-integrated nanogel (NG) platform for magnetic resonance (MR)/photoacoustic (PA) imaging-guided tumor-targeted photothermal therapy (PTT). In our approach, we prepared cross-linked polyethylenimine (PEI) NGs via an inverse emulsion method, modified the PEI NGs with Gd chelates, targeting ligand folic acid (FA) through a polyethylene glycol (PEG) spacer and 1,3-propanesultone, and finally loaded CuS nanoparticles (NPs) within the functional NGs. The as-synthesized Gd/CuS@PEI-FA-PS NGs with a mean size of 85 nm exhibit a good water dispersibility and protein resistance property, admirable r₁ relaxivity (11.66 mM^-1 s^-1), excellent NIR-II absorption feature, high photothermal conversion efficiency (26.7%), and FA-mediated targeting specificity to cancer cells overexpressing FA receptor (FAR). With these properties along with the good cytocompatibility, the developed Gd/CuS@PEI-FA-PS NGs enable MR/PA dual-mode imaging-guided targeted PTT of FAR-overexpressing tumors under the irradiation of an NIR-II (1064 nm) laser. The designed Gd/CuS@PEI-FA-PS NGs may be used as a promising theranostic agent for MR/PA dual-mode imaging-guided PTT of other FAR-expressing tumors.

Fast GPU Implementation of a Scan-Specific Deep Learning Reconstruction for Accelerated Magnetic Resonance Imaging

RAKI is a novel fast MRI image reconstruction algorithm that has been recently proposed, which gives satisfying results for highly accelerated MRI. However, due to RAKI reconstruction depends on multiple convolutional neural networks, implementing RAKI reconstruction is a time-consuming task. In this study, we present accelerate strategies for RAKI implementation aided by GPU parallel programming. Aiming at the characteristics of RAKI, we limited the iteration number of solving optimization problems in the network training stage, while maintaining the reconstruction results are visually satisfying. Further more, according to the independence between multiple networks, we parallelized the training tasks by CPU multiprocessing, which maximizes the performance by fully utilizing GPU resources. According to our experiments, these efforts gave more than 60x speed up compared with conventional, sequential implementation. With the ability of completing RAKI reconstruction in minutes, we are able to bring RAKI into practical applications.

Current Concepts in Management of Stage I NSGCT

While about 50% of non- seminomatous germ cell tumors of the testes present as clinical stage I (CSI), further management of these patients continues to be mired in controversy. Active surveillance is a frontline option for low- risk CS I patients and according to some, even the high- risk ones with high embryonal carcinoma (ECA) component and vascular invasion (VI). However, it carries the disadvantage of long- term surveillance, the need for prolonged chemotherapy in case of recurrence and the possibility of secondary malignancies due to radiation exposure from frequent CT scans. One or two cycles of BEP chemotherapy is a popular alternative to active surveillance which carries a very low relapse rate, but valid concerns about overtreatment of a majority of patients, with the attendant chemotherapy- related toxicity exist. Retroperitoneal lymph node dissection has been used as a means of avoiding chemotherapy, especially in high- risk patients, but carries the disadvantage of a high surgical morbidity and complications. As with any major surgical procedure, the best results are dependent on the experience and skill of the individual surgeon.

Schiff bases in medicinal chemistry: a patent review (2010-2015)

INTRODUCTION

Schiff bases are synthetically accessible and structurally diverse compounds, typically obtained by facile condensation between an aldehyde, or a ketone with primary amines. Schiff bases contain an azomethine (-C = N-) linkage that stitches together two or more biologically active aromatic/heterocyclic scaffolds to form various molecular hybrids with interesting biological properties. Schiff bases are versatile metal complexing agents and have been known to coordinate all metals to form stable metal complexes with vast therapeutic applications. Areas covered: This review aims to provide a comprehensive overview of the various patented therapeutic applications of Schiff bases and their metal complexes from 2010 to 2015. Expert opinion: Schiff bases are a popular class of compounds with interesting biological properties. Schiff bases are also versatile metal complexing ligands and have been used to coordinate almost all d-block metals as well as lanthanides. Therapeutically, Schiff bases and their metal complexes have been reported to exhibit a wide range of biological activities such as antibacterial including antimycobacterial, antifungal, antiviral, antimalarial, antiinflammatory, antioxidant, pesticidal, cytotoxic, enzyme inhibitory, and anticancer including DNA damage.

FDG-PET/CT in lymphoma

Lymphomas are a heterogeneous group of diseases that arise from the constituent cells of the immune system or from their precursors. 18F-fludeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is now the cornerstone of staging procedures in the state-of-the-art management of Hodgkin's disease and aggressive non-Hodgkin's lymphoma. It plays an important role in staging, restaging, prognostication, planning appropriate treatment strategies, monitoring therapy, and detecting recurrence. However, its role in indolent lymphomas is still unclear and calls for further investigational trials. The protean PET/CT manifestations of lymphoma necessitate a familiarity with the spectrum of imaging findings to enable accurate diagnosis. A meticulous evaluation of PET/CT findings, an understanding of its role in the management of lymphomas, and knowledge of its limitations are mandatory for the optimal utilization of this technique.

Magnetic resonance imaging of metastases in xenograft mouse models of cancer

Magnetic resonance imaging (MRI) of small animals has emerged as a valuable tool to noninvasively monitor tumor growth in mouse models of cancer. However, imaging of metastases in mouse models is difficult due to the need for high spatial resolution. We have demonstrated MRI of metastases in the liver, brain, adrenal glands, and lymph nodes in different xenograft mouse models of cancer. MRI of mice was performed with a clinical 3.0 T magnetic resonance scanner and a commercially available small-animal receiver coil. The imaging protocol consisted of T1- and T2-weighted fat-saturated spin echo sequences with a spatial resolution of 200 μm × 200 μm × 500 μm. Total acquisition time was 30 min per mouse. The technique allowed for repetitive examinations of larger animal cohorts to observe the development of metastases.

Rapid detection of bone metastasis at thoracoabdominal CT: accuracy and efficiency of a new visualization algorithm

PURPOSE

To retrospectively assess the use of a combination of cancellous bone reconstructions (CBR) and multiplanar reconstructions (MPRs) for the detection of bone metastases at thoracoabdominal computed tomography (CT) compared with the use of MPRs alone.

MATERIALS AND METHODS

The study was approved by the local institutional review board. Included were 156 consecutive patients with confirmed cancer who underwent a whole-body positron emission tomography (PET)/CT examination for clinical purposes (93 male and 63 female patients; mean age ± standard deviation, 59.8 years ± 14.9; range, 11-85 years). Only the CT images were processed with the CBR algorithm, which segments the bones and removes the cortical layer from the images. The PET images served as part of the reference standard. Images from 15 patients were used as a training set. Four radiologists independently evaluated images of half of the remaining 141 patients by using CBRs and MPRs together, and the other half by using MPRs only. Radiologists were blinded to patient names, and patient order was randomized. Results for detection rates and reporting time were recorded and compared with a standard of reference for each patient that was created by one senior radiologist and one nuclear medicine specialist by using all available CT and PET data, CBRs, and follow-up examinations. General estimation equations were used for statistical analysis.

RESULTS

There were 349 lesions found in 103 patients, with 203 classified as malignant. Each patient was assessed by two readers per method, leading to a total of 698 lesions. The detection rate for all bone lesions was 35% (247 of 698) for MPRs and 74% (520 of 698) when CBRs and MPRs were used together, which was significantly higher (P < .001). The average reading time decreased from 85 to 43 seconds (P < .001) when both reconstructions were used.

CONCLUSION

Advanced visualization of cancellous bone significantly increased the detection of bone metastases and reduced the time for interpretation.

Management of advanced lung cancer in resource-constrained settings: a perspective from India

Advanced lung cancer (LC) is an important cause of cancer-related morbidity and mortality in resource-constrained settings (RCSs). Cytological/pathological confirmation of diagnosis of LC is essential prior to treatment initiation for ruling out mimickers such as pulmonary tuberculosis. Accurate staging is necessary for optimal management, and investigations should be prioritized based on availability and cost-effectiveness. Platinum-based doublet chemotherapy remains the standard of care for advanced LC. Cost of therapy, lack of medical insurance and frequency of visits are important determinants of treatment regimen. EGF receptor mutation testing may not be readily available in RCSs and chemotherapy should be preferred for unselected patients with advanced non-small-cell lung cancer. Generic drugs may be more affordable than innovator brands. Treatment efficacy should be assessed with traditional end points (survival and objective response rates) as well as those relevant to RCSs (quality of life, toxicity profile and healthcare facility utilization). Issues related to LC treatment in first- and subsequent-line settings in RCSs are discussed in detail in this evidence-based review.

Retroperitoneal lymphadenectomy and resection for testicular cancer: an update on best practice

Clinical stage I testicular nonseminomatous germ cell tumours (NSGCTs) are highly curable. Following orchidectomy a risk-adapted approach using active surveillance (AS), nerve-sparing retroperitoneal lymph node dissection (nsRPLND) and primary chemotherapy is recommended by the current guidelines. Clinical stage I is defined as negative or declining tumour markers to their half-life following orchidectomy and negative imaging studies of the chest, abdomen and retroperitoneum. Active surveillance can be performed in low-risk and in high-risk NSGCTs with an anticipated relapse rate of about 15% and 50%. The majority of patients will relapse with good and intermediate prognosis tumours which have to be treated with three to four cycles chemotherapy. About 25-30% of these patients will have to undergo postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) for residual masses. Primary chemotherapy with one or two cycles of cisplatin (Platinol), etoposide and bleomycin (PEB) is a therapeutic option for high-risk clinical stage I NSGCT associated with a recurrence rate of only 2-3% and a minimal acute and long-term toxicity rate. nsRPLND, if performed properly, will cure about 85% of all high-risk patients with clinical stage I NSGCT without the need for chemotherapy. PC-RPLND forms an integral part of the multimodality treatment in patients with advanced testicular germ cell tumours (TGCTs). According to current guidelines and recommendations, PC-RPLND in advanced seminomas with residual tumours is only indicated if a positron emission tomography (PET) scan performed 6-8 weeks after chemotherapy is positive. In nonseminomatous TGCT, PC-RPLND is indicated for all residual radiographic lesions with negative or plateauing markers. Loss of antegrade ejaculation represents the most common long-term complication which can be prevented by a nerve-sparing or modified template resection. The relapse rate after PC-RPLND is around 12%, however it increases significantly to about 45% in cases with redo RPLND and late relapses. Patients with increasing markers should undergo salvage chemotherapy. Only select patients with elevated markers who are thought to be chemorefractory might undergo desperation PC-RPLND if all radiographically visible lesions are completely resectable. PC-RPLND requires a complex surgical approach and should be performed in experienced, tertiary referral centres only.

Perspectives in imaging using mass spectrometry

Imaging mass spectrometry (MS) allows a remarkable range of measurements including diagnosis of disease state of tissue based on detailed information on its chemical constituents, especially lipids and proteins. The recent emergence of ambient ionization allows imaging in the open environment without sample preparation. In this review, we briefly describe the history of imaging MS highlighting its main techniques and applications. We also demonstrate how the detailed molecular information obtained by imaging MS makes this technique suitable for a range of forensic and clinical applications with the potential to be successfully developed all the way to intra-surgical practice.

Standardised uptake value of 18F-FDG on staging PET/CT in newly diagnosed patients with different subtypes of non-Hodgkin's lymphoma

OBJECTIVES

Positron emission tomography using 2-[fluorine-18]-fluoro-2-deoxy-D-glucose ((18) F-FDG) is considered to be the most beneficial imaging method for staging patients with non-Hodgkin's lymphoma (NHL). The intensity of (18) F-FDG accumulation may be determined by calculating the so-called standardised uptake value (SUV). The study aimed at assessing the benefit of SUV(max) determination in staging (18) F-FDG PET/CT in untreated patients with NHL.

METHODS

One hundred and forty-nine initial staging (18) F-FDG PET/CT scans performed in patients with NHL between January 2007 and August 2009 were assessed, and the SUV(max) was determined.

RESULTS

The highest mean and median values of SUV(max) were observed in patients with diffuse large B-cell lymphoma (DLBCL), the lowest mean and median values were found in small lymphocytic lymphoma. The overlap in SUV(max) < 10 between DLBCL and the other subgroups of NHL was very significant. Statistically, no correlation was found between the lactate dehydrogenase and SUV(max) values. On the other hand, a correlation of the Ki-67 proliferative index of tumour cells and SUV(max) was revealed (r = 0.409, P < 0.001). The geometric mean of SUV(max) in patients with Ki-67 ≤ 60 and those with Ki-67 > 60 was 8.8 and 14.3, respectively (P < 0.001).

CONCLUSIONS

The results confirm that SUV(max) is not beneficial for making a more precise diagnosis in most patients with NHL. Correlation of SUV(max) with the Ki-67 values suggests that SUV(max) might have a prognostic values in NHL.

Cancer imaging: novel concepts in clinical magnetic resonance imaging

Cancer is a major public health problem in the Western world. Imaging is of crucial importance in oncology, because it may reduce cancer-related morbidity and mortality. To improve tumour evaluation, there is a need for functional imaging modalities that go beyond gross assessment of anatomical abnormalities and allow visualization and quantification of biochemical processes in vivo. Magnetic resonance imaging (MRI) not only provides anatomical information, but also offers a wide range of functional sequences that may aid the evaluation of cancerous lesions. Furthermore, MRI provides the opportunity to guide and monitor anticancer therapies noninvasively. The aim of this review is to highlight some of the most promising developments of MRI in the functional assessment of cancer and the guidance and monitoring of (novel) anticancer therapies.

Molecular imaging of breast cancer

Molecular imaging of breast cancer can potentially be used for breast cancer screening, staging, restaging, response evaluation and guiding therapies. Techniques for molecular breast cancer imaging include magnetic resonance imaging (MRI), optical imaging, and radionuclide imaging with positron emission tomography (PET) or single photon emission computed tomography (SPECT). This review focuses on PET and SPECT imaging which can provide sensitive serial non invasive information of tumor characteristics. Most clinical data are gathered on the visualization of general processes such as glucose metabolism with the PET-tracer [(18)F]fluorodeoxyglucose (FDG) and DNA synthesis with [18F]fluoro-L-thymidine (FLT). Increasingly more breast cancer specific targets are imaged such as the estrogen receptor (ER), growth factors and growth factor receptors. Imaging of the ER with the PET tracer 16-alpha-[(18)F]fluoro-17-beta-estradiol (FES) has shown a good correlation between FES tumor uptake and ER density. (111)In-trastuzumab SPECT to image the human epidermal growth factor receptor 2 (HER2) showed that in most patients with metastatic HER2 overexpressing disease more lesions were detected than with conventional staging procedures. The PET tracer (89)Zr-trastuzumab showed excellent, quantifiable, and specific tumor uptake. (111)In-bevacizumab for SPECT and (89)Zr-bevacizumab for PET-imaging have been developed for vascular endothelial growth factor (VEGF) imaging as an angiogenic marker. Lastly, tracers for the receptors EGFR, IGF-1R, PDGF-betaR and the ligand TGFbeta are under development. Although molecular imaging of breast cancer is still not commonly used in daily clinical practice, its application portfolio is expanding rapidly.

Synthesis, radiolabeling, and biological evaluation of (R)- and (S)-2-amino-3-[(18)F]fluoro-2-methylpropanoic acid (FAMP) and (R)- and (S)-3-[(18)F]fluoro-2-methyl-2-N-(methylamino)propanoic acid (NMeFAMP) as potential PET radioligands for imaging brain tumors

The non-natural amino acids (R)- and (S)-2-amino-3-fluoro-2-methylpropanoic acid 5 and (R)- and (S)-3-fluoro-2-methyl-2-N-(methylamino)propanoic acid 8 were synthesized in shorter reaction sequences than in the original report starting from enantiomerically pure (S)- and (R)-alpha-methyl-serine, respectively. The reaction sequence provided the cyclic sulfamidate precursors for radiosynthesis of (R)- and (S)-[(18)F]5 and (R)- and (S)-[(18)F]8 in fewer steps than in the original report. (R)- and (S)-[(18)F]5 and(R)- and (S)-[(18)F]8 were synthesized by no-carrier-added nucleophilic [(18)F]fluorination in 52-66% decay-corrected yields with radiochemical purity over 99%. The cell assays showed that all four compounds were substrates for amino acid transport and enter 9L rat gliosarcoma cells in vitro at least in part by system A amino acid transport. The biodistribution studies demonstrated that in vivo tumor to normal brain ratios for all compounds were high with ratios of 20:1 to115:1 in rats with intracranial 9L tumors. The (R)-enantiomers of [(18)F]5 and [(18)F]8 demonstrated higher tumor uptake in vivo compared to the (S)-enantiomers.

MRI-guided robotic system for transperineal prostate interventions: proof of principle

In this study, we demonstrate the proof of principle of the University Medical Center Utrecht (UMCU) robot dedicated to magnetic resonance imaging (MRI)-guided interventions in patients. The UMCU robot consists of polymers and non-ferromagnetic materials. For transperineal prostate interventions, it can be placed between the patient's legs inside a closed bore 1.5T MR scanner. The robot can manually be translated and rotated resulting in five degrees of freedom. It contains a pneumatically driven tapping device to automatically insert a needle stepwise into the prostate using a controller unit outside the scanning room. To define the target positions and to verify the needle insertion point and the needle trajectory, a high-resolution 3D balanced steady state free precession (bSSFP) scan that provides a T2/T1-weighted contrast is acquired. During the needle insertion fast 2D bSSFP images are generated to track the needle on-line. When the target position is reached, the radiation oncologist manually places a fiducial gold marker (small seed) at this location. In total two needle trajectories are used to place all markers. Afterwards, a high-resolution 3D bSSFP scan is acquired to visualize the fiducial gold markers. Four fiducial gold markers were placed transperineally into the prostate of a patient with a clinical stage T3 prostate cancer. In the generated scans, it was possible to discriminate the patient's anatomy, the needle and the markers. All markers were delivered inside the prostate. The procedure time was 1.5 h. This study proves that MRI-guided needle placement and seed delivery in the prostate with the UMCU robot are feasible.

Imaging in assessing lymph node status in gastric cancer

BACKGROUND

Accurate assessment of lymph node status is of crucial importance for appropriate treatment planning and determining prognosis in patients with gastric cancer. The aim of this study was to systematically review the current role of imaging in assessing lymph node (LN) status in gastric cancer.

METHODS

A systematic literature search was performed in the PubMed/MEDLINE and Embase databases. The methodological quality and diagnostic performance of the included studies was assessed.

RESULTS

Six abdominal ultrasonography (AUS) studies, 30 endoscopic ultrasonography (EUS) studies, 10 multidetectorrow computed tomography (MDCT) studies, 3 conventional magnetic resonance imaging (MRI) studies, 4 (18)F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) studies, and 1 FDG-PET/CT fusion study were included. In general, the included studies had moderate methodological quality. The sensitivity and specificity of AUS varied between 12.2% and 80.0% (median, 39.9%) and 56.3% and 100% (median, 81.8%). The sensitivity and specificity of EUS varied between 16.7% and 95.3% (median, 70.8%) and 48.4% and 100% (median, 84.6%). The sensitivity and specificity of MDCT varied between 62.5% and 91.9% (median, 80.0%) and 50.0% and 87.9% (median, 77.8%). The sensitivity and specificity of MRI varied between 54.6% and 85.3% (median, 68.8%) and 50.0% and 100% (median, 75.0%). The sensitivity and specificity of FDG-PET varied between 33.3% and 64.6% (median, 34.3%) and 85.7% and 97.0% (median, 93.2%). The sensitivity and specificity of the FDG-PET/CT fusion study were 54.7% and 92.2%. For all the imaging modalities, there were no significant differences between the mean sensitivities and specificities of high- and low-quality studies.

CONCLUSION

AUS, EUS, MDCT, conventional MRI, and FDG-PET cannot reliably be used to confirm or exclude the presence of LN metastasis. The performance of highresolution PET/CT fusion and functional MRI techniques still has to be determined.

Tumor detection using folate receptor-targeted imaging agents

Folate receptors are up-regulated on a variety of human cancers, including cancers of the breast, ovaries, endometrium, lungs, kidneys, colon, brain, and myeloid cells of hematopoietic origin. This over-expression of folate receptors (FR) on cancer tissues can be exploited to target folate-linked imaging and therapeutic agents specifically to FR-expressing tumors, thereby avoiding uptake by most healthy tissues that express few if any FR. Four folate-targeted therapeutic drugs are currently undergoing clinical trials, and several folate-linked chemotherapeutic agents are in late stage preclinical development. However, because not all cancers express FR, and because only FR-expressing cancers respond to FR-targeted therapies, FR-targeted imaging agents have been required to select patients with FR-expressing tumors likely to respond to folate-targeted therapies. This review focuses on recent advances in the use of the vitamin folic acid to target PET agents, gamma-emitters, MRI contrast agents and fluorescent dyes to FR(+) cancers for the purpose of diagnosing and imaging malignant masses with improved specificity and sensitivity.

The impact of fluorodeoxyglucose-positron emission tomography in primary staging and patient management in lymphoma patients

Fully diagnostic positron emission tomography (PET)/CT scans acquired during oral and intravenous contrast can be provided to patients and referring physicians in a single imaging session. Although FDG uptake varies, most low-grade lymphomas exhibit sufficient FDG avidity to also be staged reliably with FDG PET/CT. PET/CT imaging is more accurate for lymphoma staging than PET or CT alone and has substantial impact on patient management. This accurate whole-body glucose metabolic survey should serve as the baseline for subsequent treatment response evaluations. PET/CT has evolved to become the modality of choice for staging of nodal and extranodal lymphoma, for assessing therapeutic response, and for establishing patient prognosis.

Improving lesion detection and visualization: implications for neurosurgical planning and follow-up

Contrast-enhanced magnetic resonance (MR) imaging is considered the most sensitive method for detecting tumors in the central nervous system (CNS). The primary objective is to improve lesion detection, delineation, and characterization (benign or malignant) in order to more accurately define the location, extent, and type of disease and the appropriate treatment option for improved patient outcome (surgical intervention, radiation therapy or cytotoxic chemotherapy). This article reviews the various types of tumor occurring in the brain and the specific role of contrast-enhanced MR imaging for the evaluation of these tumors. Emphasis is placed on the value of contrast-enhanced MR imaging in the evaluation of primary intra-axial brain lesions and how high relaxivity contrast agents such as MultiHance (Bracco Imaging, Milan, Italy) might improve detection, treatment planning, and follow-up.

Bispecific antibody pretargeting of radionuclides for immuno single-photon emission computed tomography and immuno positron emission tomography molecular imaging: an update

Molecular imaging is intended to localize disease based on distinct molecular/functional characteristics. Much of today's interest in molecular imaging is attributed to the increased acceptance and role of 18F-flurodeoxyglucose (18F-FDG) imaging in a variety of tumors. The clinical acceptance of 18F-FDG has stimulated research for other positron emission tomography (PET) agents with improved specificity to aid in tumor detection and assessment. In this regard, a number of highly specific antibodies have been described for different cancers. Although scintigraphic imaging with antibodies in the past was helpful in patient management, most antibody-based imaging products have not been able to compete successfully with the sensitivity afforded by 18F-FDG-PET, especially when used in combination with computed tomography. Recently, however, significant advances have been made in reengineering antibodies to improve their targeting properties. Herein, we describe progress being made in using a bispecific antibody pretargeting method for immuno-single-photon emission computed tomography and immunoPET applications, as contrasted to directly radiolabeled antibodies. This approach not only significantly enhances tumor/nontumor ratios but also provides high signal intensity in the tumor, making it possible to visualize micrometastases of colonic cancer as small as 0.1 to 0.2 mm in diameter using an anti-carcinoembryonic antigen bispecific antibody, whereas FDG failed to localize these lesions in a nude mouse model. Early detection of micrometastatic non-Hodgkin's lymphoma is also possible using an anti-CD20-based bispecific antibody pretargeting procedure. Thus, this bispecific antibody pretargeting procedure may contribute to tumor detection and could also contribute to the detection of other diseases having distinct antigen targets and suitably specific antibodies.

Imaging in staging of malignant lymphoma: a systematic review

Computed tomography (CT) is currently the most commonly used means for staging malignant lymphoma. 18F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET), FDG-PET/CT fusion, and whole-body magnetic resonance imaging (WB-MRI) are potential alternatives. The purpose of this study was to systematically review published data on the diagnostic performance of CT, FDG-PET, FDG-PET/CT fusion, and WB-MRI in staging of malignant lymphoma. In addition, technical aspects, procedures, advantages, and drawbacks of each imaging modality are outlined. Three CT studies, 17 FDG-PET studies, and 4 FDG-PET/CT fusion studies were included in this systematic review. The studies were of moderate methodological quality and used different scoring systems to stage malignant lymphoma. CT remains the standard imaging modality for initial staging of malignant lymphoma, while FDG-PET has an essential role in restaging after treatment. Early results suggest that FDG-PET/CT fusion outperforms both CT alone and FDG-PET alone. Data on the diagnostic performance of WB-MRI are lacking. Future well-designed studies, expressing their results according to the Ann Arbor staging system, are needed to determine which imaging modality is most accurate and cost-effective in staging malignant lymphoma.

Imaging in local staging of gastric cancer: a systematic review

PURPOSE

Endoscopic ultrasound (EUS) has been established as the diagnostic modality of choice in local (T) staging of gastric cancer. Multidetector row computed tomography (MDCT) and magnetic resonance imaging (MRI) are promising alternatives. The aim of this study was to systematically review the literature regarding the performance of each of these imaging modalities.

METHODS

A systematic search for relevant studies was performed in the PubMed/MEDLINE and EMBASE databases. Two reviewers independently assessed the methodological quality of each study. Local staging performance of included studies was calculated.

RESULTS

Twenty-two EUS studies, five MDCT studies, one combined EUS and MDCT study, and three MRI studies met the inclusion criteria. The studies were of moderate methodological quality. Diagnostic accuracy of overall T staging for EUS, MDCT, and MRI varied between 65% to 92.1%, 77.1% to 88.9%, and 71.4% to 82.6%, respectively. Sensitivity for assessing serosal involvement for EUS, MDCT, and MRI varied between 77.8% to 100%, 82.8% to 100%, and 89.5% to 93.1%, respectively. Specificity for assessing serosal involvement for EUS, MDCT, and MRI varied between 67.9% to 100%, 80% to 96.8%, and 91.4% to 100%, respectively.

CONCLUSION

EUS, MDCT, and MRI achieve similar results in terms of diagnostic accuracy in T staging and in assessing serosal involvement. Most experience has been gained with EUS. Few MDCT studies and even fewer MRI studies are available. Thus, EUS remains the first-choice imaging modality in preoperative T staging of gastric cancer.