Cystic pancreatic endocrine neoplasms: a distinct tumor type?

BACKGROUND: Cystic pancreatic endocrine neoplasms (CPENs) are considered rare, and their behavior is thought to be similar to that of solid pancreatic endocrine neoplasms (PENs). This study aims to describe the characteristics of CPENs in a large patient cohort. STUDY DESIGN: We performed a retrospective review of 170 patients who underwent resections for PENs at Massachusetts General Hospital from 1977 to 2006. Twenty-nine patients (51% men, mean age 53) with CPENs were compared with 141 patients with solid PENs. Differences in clinical presentation, pathologic and radiographic features, and survival were described. RESULTS: CPENs comprised 17% of all PENs (29 of 170) and 5.4% of all resected cystic pancreatic neoplasms(29 of 535). Ten (34%) were purely cystic and 19 (66%) were partially cystic. Compared with solid PENs, CPENs were larger (49 mm versus 23.5 mm, p < 0.05), more likely symptomatic (73% versus 45%, p < 0.05), and more likely nonfunctional (80% versus 50%, p < 0.05). They expressed synaptophysin (100%), chromogranin (82%), and cytokeratin (CK)-19 (24%). Multiple endocrine neoplasia type 1 (MEN-1) was 3.5 times more common in CPENs than in solid tumors (21% versus 6%, p < 0.05). No significant difference was found in location, propensity for metastasis, invasion, or 5-year survival (87% versus 77%, p=0.38). CONCLUSIONS: This series, the largest report of CPENs in the literature, shows that CPENs are more common than previously thought, so they should be included in the differential of the cystic lesions of the pancreas. CPENs are larger and more likely to be symptomatic then solid PENs. They are also more likely to be associated with MEN-1 and to be nonfunctional, suggesting they may be a distinct tumor type.     

Neoplasms of the perivascular epithelioid cell involving the abdomen and the pelvis: cross-sectional imaging findings

Neoplasms of the perivascular epithelioid cell (PEComas) represent a recently described heterogeneous group of mesenchymal tumors characterized by the presence of specific histological, immunohistochemical, and ultrastructural findings. The PEComas encompass a family of neoplasms that include angiomyolipomas, clear cell sugar tumors, and lymphangioleiomyomatosis. The PEComas demonstrate a wide spectrum of clinicobiological behavior and imaging findings. Perivascular epithelioid cell, as the name implies, is a unique cell that is characterized by perivascular distribution and epithelioid morphology. Perivascular epithelioid cell consistently shows immunoreactivity to melanocytic and smooth muscle markers including HMB-45 and actin. Abdominopelvic PEComas are found at a variety of somatic and visceral locations including kidney, liver, pancreas, gastrointestinal tract, genitourinary tract, peritoneum, and retroperitoneum. A subset of patients with abdominopelvic PEComas manifests tuberous sclerosis complex. In this paper, we review the histological spectrum and discuss the imaging findings of the PEComas that involve the abdomen and pelvis.     

Proton-Beam,Intensity-Modulated,and/or Intraoperative Electron Radiation Therapy Combined with Aggressive Anterior Surgical Resection for Retroperitoneal Sarcomas

Background  

We sought to reduce local recurrence for retroperitoneal sarcomas by using a coordinated strategy of advanced radiation techniques and aggressive en-bloc surgical resection.     

Colonic carcinoma after chemotherapy of Hodgkin's disease

We describe a 28-year-old man with stage IV-B Hodgkin's disease who developed an adenocarcinoma of the colon after treatment with combination chemotherapy. To the best of our knowledge, this patient is the youngest, and only the fourth person in the English-language literature to develop colonic carcinoma after combination chemotherapy of Hodgkin's disease without radiation.     

Iodine material density images in dual-energy CT: quantification of contrast uptake and washout in HCC

Purpose

To determine the diagnostic potential of Material Density (MD) iodine images in dual-energy CT (DECT) for visualization and quantification of arterial phase hyperenhancement and washout in hepatocellular carcinomas compared to magnetic resonance imaging (MRI).

Materials and Methods

The study complied with HIPAA guidelines and was approved by the ethics committee of the institutional review board. Thirty-one patients (23 men, 8 women; age range, 36–87 years) with known or suspected Hepatocellular Carcinoma (HCC) were included. All of them underwent both single-source DECT and MRI within less than 3 months. Late arterial phase and portal venous phase CT imaging was performed with dual energies of 140 and 80 kVp, and virtual monoenergetic images (at 65 keV) and MD-iodine images were generated. We determined the contrast-to-noise ratio (CNR) for HCC in arterial phase and portal venous phase images. In addition, we introduced a new parameter which combines information of CNR in arterial and portal venous phase images into a single ratio (combined CNR). All parameters were assessed on monoenergetic 65 keV images, MD-iodine images, and MRI. Paired t test was used to compare CNR values in Mono-65 keV, MD-iodine, and MR images.

Results

CNR was significantly higher in the MD-iodine images in both the arterial (81.87 ± 40.42) and the portal venous phases (33.31 ± 27.86), compared to the Mono-65 keV (6.34 ± 4.23 and 1.89 ± 1.87) and MRI (30.48 ± 25.52 and 8.27 ± 8.36), respectively. Combined CNR assessment from arterial and portal venous phase showed higher contrast ratios for all imaging modalities (Mono-65 keV, 8.73 ± 4.03; MD-iodine, 119.87 ± 52.94; MRI, 34.87 ± 27.34). In addition, highest contrast ratio was achieved in MD-iodine images with combined CNR evaluation (119.87 ± 52.94, P < 0.001).

Conclusion

MD-iodine images in DECT allow for a quantitative assessment of contrast enhancement and washout, with improved CNR in hepatocellular carcinoma in comparison to MRI.

     

Improved tumor vascularization after anti-VEGF therapy with carboplatin and nab-paclitaxel associates with survival in lung cancer

Addition of anti-VEGF antibody therapy to standard chemotherapies has improved survival and is an accepted standard of care for advanced non–small cell lung cancer (NSCLC). However, the mechanisms by which anti-VEGF therapy increases survival remain unclear. We evaluated dynamic CT-based vascular parameters and plasma cytokines after bevacizumab alone and after bevacizumab plus chemotherapy with carboplatin and nab-paclitaxel in advanced NSCLC patients to explore potential biomarkers of treatment response and resistance to this regimen. Thirty-six patients were enrolled in this study. The primary end point was 6-mo progression-free survival rate, which was 74% (95% CI: 57, 97). This regimen has a promising overall response rate of 36% and median time to progression of 8.5 (6.0, 38.7) mo and overall survival of 12.2 (9.6, 44.1) mo. We found that anti-VEGF therapy led to a sustained increase in plasma PlGF, a potential pharmacodynamic marker. We also found that higher levels of soluble VEGFR1 measured before starting bevacizumab with chemotherapy were associated with worse survival, supporting its potential role as biomarker of treatment resistance. Our imaging biomarker studies indicate that bevacizumab-based treatment—while reducing blood flow, volume, and permeability in the overall population—may be associated with improved survival in patients with improved tumor vasculature and blood perfusion after treatment. This hypothesis-generating study supports the notion that excessively decreasing vascular permeability and pruning/rarefaction after bevacizumab therapy may negatively impact the outcome of combination therapy in NSCLC patients. This hypothesis warrants further dose-titration studies of bevacizumab to examine the dose effect on tumor vasculature and treatment efficacy.The advent of targeted therapies has led to an unprecedented increase in the median overall survival (OS) in advanced non–small cell lung cancer (NSCLC), well beyond 1 y. This progress included the successful development of antiangiogenic drugs such as bevacizumab or ramucirumab in combination with chemotherapy (1, 2). However, although the use of cancer cell-targeted drugs is guided by biomarkers (e.g., EGFR mutations, ALK-EML4 translocations), there are currently no biomarkers for antiangiogenic drugs. In advanced NSCLC, the use of the anti-VEGF antibody bevacizumab in combination with platinum-based chemotherapy is a widely accepted standard of care in nonsquamous histology (1). However, the mechanism by which bevacizumab improves survival over chemotherapy alone remains debated.Originally, it was hypothesized that antiangiogenic agents would effectively starve the tumor of oxygen and nutrients by pruning the blood vessel system and reducing blood perfusion to tumors (3). However, this effect would eventually lead to both decreased drug delivery (and hence treatment resistance) and increased tumor hypoxia (a major driver of tumor progression) (4). Another potential mechanism of antiangiogenic therapy is transient vascular normalization, by which structurally and functionally abnormal tumor vasculature is normalized, i.e., remodeled or modified to more closely resemble normal vasculature (4). By attenuation of vascular hyperpermeability, increasing vessel pericyte coverage, and normalization of the basement membrane, vascular normalization may lead to reduced interstitial fluid pressure and improved blood perfusion. This normalization may have important consequences on drug and oxygen delivery and on the immune microenvironment (5–8). Finally, it remains unclear whether bevacizumab’s efficacy is dependent on the chemotherapeutic regimen used.Unfortunately, clinical data exploring these mechanisms in NSCLC are scarce. Van der Veldt et al. reported that bevacizumab reduced perfusion and net influx rate of radiolabeled docetaxel in 10 patients with advanced NSCLC (9). Bevacizumab administration significantly reduced drug uptake measured by PET starting at 5 h after and persisting until day 4. Whether this effect was associated with benefit or treatment resistance remains unknown. Furthermore, although the carboplatin and albumin-bound paclitaxel (nab-paclitaxel) regimen has shown superiority in response rate over carboplatin and paclitaxel in a large phase III study (10) leading to its approval for NSCLC patients, the addition of bevacizumab to this regimen is yet to be thoroughly tested. We conducted a phase II trial that investigated the regimen of carboplatin and nab-paclitaxel in combination with bevacizumab for the first-line treatment of patients with advanced (stage IIIB/IV) nonsquamous NSCLC. In this study, we evaluated imaging and circulating biomarkers after bevacizumab alone and after bevacizumab plus chemotherapy to explore potential biomarkers of treatment response and resistance to this regimen. We found that markers of improved tumor blood perfusion after anti-VEGF therapy with carboplatin and nab-paclitaxel were associated with improved survival in these patients.     

Cranial CT with adaptive statistical iterative reconstruction: improved image quality with concomitant radiation dose reduction

BACKGROUND AND PURPOSE:To safeguard patient health, there is great interest in CT radiation-dose reduction. The purpose of this study was to evaluate the impact of an iterative-reconstruction algorithm, ASIR, on image-quality measures in reduced-dose head CT scans for adult patients.MATERIALS AND METHODS:Using a 64-section scanner, we analyzed 100 reduced-dose adult head CT scans at 6 predefined levels of ASIR blended with FBP reconstruction. These scans were compared with 50 CT scans previously obtained at a higher routine dose without ASIR reconstruction. SNR and CNR were computed from Hounsfield unit measurements of normal GM and WM of brain parenchyma. A blinded qualitative analysis was performed in 10 lower-dose CT datasets compared with higher-dose ones without ASIR. Phantom data analysis was also performed.RESULTS:Lower-dose scans without ASIR had significantly lower mean GM and WM SNR (P = .003) and similar GM-WM CNR values compared with higher routine-dose scans. However, at ASIR levels of 20%–40%, there was no statistically significant difference in SNR, and at ASIR levels of ≥60%, the SNR values of the reduced-dose scans were significantly higher (P < .01). CNR values were also significantly higher at ASIR levels of ≥40% (P < .01). Blinded qualitative review demonstrated significant improvements in perceived image noise, artifacts, and GM-WM differentiation at ASIR levels ≥60% (P < .01).CONCLUSIONS:These results demonstrate that the use of ASIR in adult head CT scans reduces image noise and increases low-contrast resolution, while allowing lower radiation doses without affecting spatial resolution.

The use of CT is increasing rapidly at a rate of approximately 10% per year, and >68 million CT studies were performed in the United States during 2008.^1–3 The foremost concern with the increasing use of CT technology is the associated dose of ionizing radiation and the potential risk of cancer development later in life.¹ The situation is even more worrisome in the pediatric population, which is at greater risk than adults from a given dose of radiation.¹ However, dose reduction in CT is hindered by the increased image noise in lower radiation-dose protocols by using the current FBP reconstructions.CT imaging demands the development of more efficient reconstruction techniques to diminish radiation dose. Iterative reconstruction techniques promise to drastically reduce image noise and artifacts, thereby allowing significant dose reduction. Most of these techniques are computationally intensive and require long reconstruction times. The most comprehensive iterative-reconstruction algorithm models the system optics by taking into account the finite size of the pixel and the focal spot as well as the shape and size of the detector-cell spacing. In addition, it also models the photon statistics in x-ray attenuation. ASIR (GE Healthcare, Chalfont St. Giles, UK) is a modified iterative-reconstruction technique that is time-efficient and already clinically available. It models the photon statistics in x-ray attenuation but does not model the system optics. Thus, it is more computationally complex than FBP but considerably less computationally complex than more comprehensive iterative-reconstruction methods.³ This technique produces significant noise reduction that potentially improves image quality and allows reduction in radiation dose. High levels of ASIR processing create image texture (smooth appearance) and noise characteristics unfamiliar to radiologists.^3,4 In clinical practice, one can use variably blended images created with FBP and ASIR techniques to produce different levels of ASIR.The purpose of this study was to evaluate the impact of ASIR on both qualitative and quantitative measures of image quality in reduced-dose head CT scans for adult patients. Our hypothesis was that the use of ASIR decreases CT image noise resulting in increased SNR and CNR ratios as well as improved qualitative scores of contrast resolution without compromising spatial resolution. We evaluated its effect on quantitative and qualitative measures of brain image quality in adult reduced-dose head CT scans at multiple ASIR levels in comparison with regular-dose CT studies.