Evaluation of an iterative model-based CT reconstruction algorithm by intra-patient comparison of standard and ultra-low-dose examinations.

Background The explosive growth of computer tomography (CT) has led to a growing public health concern about patient and population radiation dose. A recently introduced technique for dose reduction, which can be combined with tube-current modulation, over-beam reduction, and organ-specific dose reduction, is iterative reconstruction (IR). Purpose To evaluate the quality, at different radiation dose levels, of three reconstruction algorithms for diagnostics of patients with proven liver metastases under tumor follow-up. Material and Methods A total of 40 thorax-abdomen-pelvis CT examinations acquired from 20 patients in a tumor follow-up were included. All patients were imaged using the standard-dose and a specific low-dose CT protocol. Reconstructed slices were generated by using three different reconstruction algorithms: a classical filtered back projection (FBP); a first-generation iterative noise-reduction algorithm (iDose4); and a next generation model-based IR algorithm (IMR). Results The overall detection of liver lesions tended to be higher with the IMR algorithm than with FBP or iDose4. The IMR dataset at standard dose yielded the highest overall detectability, while the low-dose FBP dataset showed the lowest detectability. For the low-dose protocols, a significantly improved detectability of the liver lesion can be reported compared to FBP or iDose4 ( P = 0.01). The radiation dose decreased by an approximate factor of 5 between the standard-dose and the low-dose protocol. Conclusion The latest generation of IR algorithms significantly improved the diagnostic image quality and provided virtually noise-free images for ultra-low-dose CT imaging.

Volumetric gain of the human pancreas after left partial pancreatic resection: A CT-scan based retrospective study.

BACKGROUND/OBJECTIVES: Regeneration of the pancreas has been well characterized in animal models. However, there are conflicting data on the regenerative capacity of the human pancreas. The aim of the present study was to assess the regenerative capacity of the human pancreas. METHODS: In a retrospective study, data from patients undergoing left partial pancreatic resection at a single center were eligible for inclusion (n = 185). Volumetry was performed based on 5 mm CT-scans acquired through a 256-slice CT-scanner using a semi-automated software. RESULTS: Data from 24 patients (15 males/9 females) were included. Mean ± SD age was 68 ± 11 years (range, 40-85 years). Median time between surgery and the 1st postoperative CT was 9 days (range, 0-27 days; IQR, 7-13), 55 days (range, 21-141 days; IQR, 34-105) until the 2nd CT, and 191 days (range, 62-1902; IQR, 156-347) until the 3rd CT. The pancreatic volumes differed significantly between the first and the second postoperative CT scans (median volume 25.6 mL and 30.6 mL, respectively; p = 0.008) and had significantly increased further by the 3rd CT scan (median volume 37.9 mL; p = 0.001 for comparison with 1st CT scan and p = 0.003 for comparison with 2nd CT scan). CONCLUSIONS: The human pancreas shows a measurable and considerable potential of volumetric gain after partial resection. Multidetector-CT based semi-automated volume analysis is a feasible method for follow-up of the volume of the remaining pancreatic parenchyma after partial pancreatectomy. Effects on exocrine and endocrine pancreatic function have to be evaluated in a prospective manner.

Post-therapeutic response evaluation by a combination of endoscopy and CT scan in esophagogastric adenocarcinoma after chemotherapy: better than its reputation.

BACKGROUND: Neoadjuvant chemotherapy is an accepted standard of care for locally advanced esophagogastric cancer. As only a subgroup benefits, a response-based tailored treatment would be of interest. The aim of our study was the evaluation of the prognostic and predictive value of clinical response in esophagogastric adenocarcinomas. METHODS: Clinical response based on a combination of endoscopy and computed tomography (CT) scan was evaluated retrospectively within a prospective database in center A and then transferred to center B. A total of 686/740 (A) and 184/210 (B) patients, staged cT3/4, cN0/1 underwent neoadjuvant chemotherapy and were then re-staged by endoscopy and CT before undergoing tumor resection. Of 184 patients, 118 (B) additionally had an interim response assessment 4-6 weeks after the start of chemotherapy. RESULTS: In A, 479 patients (70%) were defined as clinical nonresponders, 207 (30%) as responders. Median survival was 38 months (nonresponders: 27 months, responders: 108 months, log-rank, p < 0.001). Clinical and histopathological response correlated significantly (p < 0.001). In multivariate analysis, clinical response was an independent prognostic factor (HR for death 1.4, 95% CI 1.0-1.8, p = 0.032). In B, 140 patients (76%) were nonresponders and 44 (24%) responded. Median survival was 33 months, (nonresponders: 27 months, responders: not reached, p = 0.003). Interim clinical response evaluation (118 patients) also had prognostic impact (p = 0.008). Interim, preoperative clinical response and histopathological response correlated strongly (p < 0.001). CONCLUSION: Preoperative clinical response was an independent prognostic factor in center A, while in center B its prognostic value could only be confirmed in univariate analysis. The accordance with histopathological response was good in both centers, and interim clinical response evaluation showed comparable results to preoperative evaluation.

Is preoperative chemotherapy followed by surgery the appropriate treatment for signet ring cell containing adenocarcinomas of the esophagogastric junction and stomach?

BACKGROUND: Recent data suggest primary resection as the preferable approach in patients with signet ring cell gastric cancer (SRC). The aim of our retrospective exploratory study was to evaluate the influence of SRC on prognosis and response in esophagogastric adenocarcinoma treated with neoadjuvant chemotherapy. METHODS: A total of 723 locally advanced esophagogastric adenocarcinomas (cT3/4 N any) documented in a prospective database from two academic centers were classified according to the WHO definition for SRC (more than 50 % SRC) and analyzed for their association with response and prognosis after neoadjuvant treatment. RESULTS: A total of 235 tumors (32.5 %) contained SRC. Median survival of SRC was 26.3 compared with 46.6 months (p < 0.001) for non-SRC. SRC were significantly associated with female gender, gastric localization, advanced ypT and R1/2 categories, and lower risk of surgical complications and anastomotic leakage (each p < 0.001). Clinical (21.1 vs. 33.7 %, p = 0.001) and histopathological response (less than 10 % residual tumor: 16.3 vs. 28.9 %, p < 0.001) were significantly less frequent in SRC. Clinical response (p = 0.003) and complete histopathological response (pCR) (3.4 %) (p = 0.003) were associated with improved prognosis in SRC. Clinical response, surgical complications, ypTN categories, but not SRC were independent prognostic factors in forward Cox regression analysis in R0 resected patients. Risk of peritoneal carcinomatosis was increased (p < 0.001), while local (p = 0.015) and distant metastases (p = 0.02) were less frequent than in non-SRC. CONCLUSIONS: Prognosis of SRC is unfavorable. Although response to neoadjuvant chemotherapy is rare in SRC, it is associated with improved outcome. Thus, chemotherapy might not generally be abandoned in SRC. A stratification based on SRC should be included in clinical trials.

Three-dimensional prediction of free-flap volume in autologous breast reconstruction by CT angiography imaging.

PURPOSE: The diagnostic use of computer tomography angiography (CTA) to identify perforating blood vessels for abdominal free-flap breast reconstruction was extended to estimate the three-dimensional (3D) preoperative flap volume and to compare it with the real intraoperative flap weights in order to (1) evaluate the accuracy of CTA-based 3D flap volume prediction, and (2) to analyze abdominal tissue estimation for required breast volume reconstruction. METHODS: Preoperative CTA was performed in 54 patients undergoing unilateral breast reconstruction with a free, deep, inferior epigastric artery perforator flap. 3D flap volumes ([Formula: see text]) based on CTA data were calculated and compared with the actual intraoperative flap weight (g). In addition, a breast volume to flap volume ratio was calculated to analyze whether the estimated 3D abdominal flap volume would match that of the breast to be removed. RESULTS: 40 CTA data sets (74.1 %) fulfilled the technical requirements for a reliable determination of flap volume. 3D CTA flap volume prediction showed no relevant differences to the actual flap weight (p = 0.44) and high correlations (r = 0.998, [Formula: see text]), allowing a prediction accuracy within 0.29 [Formula: see text] 3.0 % (range: from [Formula: see text]8.77 to 5.67 %) of the real flap weight. Significantly larger flap volumes were harvested compared with the actually required breast volumes ([Formula: see text]), leading to an average of 21 % of the remnant flap tissue potentially being discarded. CONCLUSIONS: CTA-based 3D flap volume prediction provides accurate preoperative guidelines concerning the needed amount of abdominal tissue that can be harvested to achieve acceptable symmetry.

Evaluation of a method for improving the detection of hepatocellular carcinoma.

OBJECTIVE: To improve the detection of liver lesions in patients with hepatocellular carcinoma (HCC) via an iodine contrast enhancement tool. METHODS: Thirty-two patients with clinically proven HCCs underwent imaging with a three-phase protocol on a 256-slice MDCT. The contrast enhancement in the reconstructed slices was improved via a post-processing tool. Mean image noise was measured in four different regions: liver lesion, healthy liver, subcutaneous fat and bone. For each image set the image noise and contrast-to-noise ratio (CNR) were assessed. For subjective image assessment, four experienced radiologists evaluated the diagnostic quality. RESULTS: While employing the post-processing algorithm, CNR between the liver lesion and healthy liver tissue improves significantly by a factor of 1.78 (CNRwithout vC = 2.30 ± 1.92/CNRwith vC = 4.11 ± 3.05) (P* = 0.01). All results could be achieved without a strengthening of artefacts; mean HU values of subcutaneous fat and bone did not significantly change. Subjective image analysis illustrated a significant improvement when employing post-processing for clinically relevant criteria such as diagnostic confidence. CONCLUSION: With post-processing we see a significantly improved detection of arterial uptake in hepatic lesions compared with non-processed data. The improvement in CNR was confirmed by subjective image assessment for small lesions and for lesions with limited uptake. KEY POINTS: • Enhancement with iodine-based contrast agents is an essential part of CT. • A new post-processing tool significantly improves the diagnostics of hepatocellular carcinoma. • It also improves detection of small lesions with limited iodine uptake.

Interim endoscopy results during neoadjuvant therapy for gastric cancer correlate with histopathological response and prognosis.

BACKGROUND: Neoadjuvant chemotherapy for locally advanced gastric cancer leads to major histopathological response in less than 30 % of patients. Data on interim endoscopic response assessment do not exist. This exploratory prospective study evaluates early endoscopy after 50 % of the chemotherapy as predictor for later response and prognosis. METHODS: Forty-seven consecutive patients were included (45 resected; 33 R0 resections). All patients received baseline endoscopy and CT scans, after 50 % of their chemotherapy (EGD-1, CT-1) and after completion of chemotherapy (EGD-2, CT-2). Interim endoscopic response (EGD-1) was assessed after having received 50 % (6 weeks) of the planned 12 weeks of neoadjuvant chemotherapy. Post-chemotherapy response was clinically assessed by a combination of CT scan (CT-2) and endoscopy (EGD-2). Histopathological response was determined by a standardized scoring system (Becker criteria). Endoscopic response was defined as a reduction of >75 % of the tumor mass. RESULTS: Twelve patients were responders at EGD-1 and 13 at EGD-2. Nine patients (19.1 %) were clinical responders and 7 patients (15.6 %) were histopathological responders after chemotherapy. Specificity, accuracy, and negative predictive value of the interim EGD-1 for subsequent histopathological response were 31/38 (82 %), 36/47 (76 %), and 31/33 (93 %); and for recurrence or death, 28/30 (93.3 %), 38/47 (80.9 %), and 28/35 (80.0 %). Response at EGD-1 was significantly associated with histopathological response (p = 0.010), survival (p < 0.001), and recurrence-free survival (p = 0.009). CONCLUSIONS: Interim endoscopy after 6 weeks predicts response and prognosis. Therefore, tailoring treatment according to interim endoscopic assessment could be feasible, but the findings of this study should be validated in a larger patient cohort.

Does iterative reconstruction lower CT radiation dose: evaluation of 15,000 examinations.

PURPOSE: Evaluation of 15,000 computed tomography (CT) examinations to investigate if iterative reconstruction (IR) reduces sustainably radiation exposure. METHOD AND MATERIALS: Information from 15,000 CT examinations was collected, including all aspects of the exams such as scan parameter, patient information, and reconstruction instructions. The examinations were acquired between January 2010 and December 2012, while after 15 months a first generation IR algorithm was installed. To collect the necessary information from PACS, RIS, MPPS and structured reports a Dose Monitoring System was developed. To harvest all possible information an optical character recognition system was integrated, for example to collect information from the screenshot CT-dose report. The tool transfers all data to a database for further processing such as the calculation of effective dose and organ doses. To evaluate if IR provides a sustainable dose reduction, the effective dose values were statistically analyzed with respect to protocol type, diagnostic indication, and patient population. RESULTS: IR has the potential to reduce radiation dose significantly. Before clinical introduction of IR the average effective dose was 10.1±7.8mSv and with IR 8.9±7.1mSv (p*=0.01). Especially in CTA, with the possibility to use kV reduction protocols, such as in aortic CTAs (before IR: average14.2±7.8mSv; median11.4mSv /with IR:average9.9±7.4mSv; median7.4mSv), or pulmonary CTAs (before IR: average9.7±6.2mSV; median7.7mSv /with IR: average6.4±4.7mSv; median4.8mSv) the dose reduction effect is significant(p*=0.01). On the contrary for unenhanced low-dose scans of the cranial (for example sinuses) the reduction is not significant (before IR:average6.6±5.8mSv; median3.9mSv/with IR:average6.0±3.1mSV; median3.2mSv). CONCLUSION: The dose aspect remains a priority in CT research. Iterative reconstruction algorithms reduce sustainably and significantly radiation dose in the clinical routine. Our results illustrate that not only in studies with a limited number of patients but also in the clinical routine, IRs provide long-term dose saving.

Rapid assessment of liver volumetry by a novel automated segmentation algorithm.

OBJECTIVE: This study aimed to evaluate a novel segmentation software for automated liver volumetry and segmentation regarding segmentation speed and interobserver variability. METHODS: Computed tomographic scans of 20 patients without underlying liver disease and 10 patients with liver metastasis from colorectal cancer were analyzed by a novel segmentation software. Liver segmentation was performed after manual placement of specific landmarks into 9 segments according to the Couinaud model as well as into 4 segments, the latter being import for surgery planning. Time for segmentation was measured and the obtained segmental and total liver volumes between the different readers were compared calculating intraclass correlations (ICCs). Volumes of liver tumor burden were evaluated similarly. RESULTS: Liver segmentation could be performed rapidly 3 minutes or less. Comparison of total liver volumes revealed a perfect ICC of greater than 0.997. Segmental liver volumes within the 9-part segmentation provided fair to moderate correlation for the left lobe and good to excellent correlations for the right lobe. When applying a 4-part segmentation relevant to clinical practice, strong to perfect agreement was observed. Similarly tumor volumes showed perfect ICC (>0.998). CONCLUSIONS: Rapid determination of total and segmental liver volumes can be obtained using a novel segmentation software suitable for daily clinical practice.

How fibrosis influences imaging and surgical decisions in pancreatic cancer.

Our understanding of pancreatic ductal adenocarcinoma (PDAC) is shifting away from a disease of malignant ductal cells-only, toward a complex system where tumor evolution is a result of interaction of cancer cells with their microenvironment. This change has led to intensification of research focusing on the fibrotic stroma of PDAC. Pancreatic stellate cells (PSCs) are the main fibroblastic cells of the pancreas which are responsible for producing the desmoplasia in chronic pancreatitis (CP) and PDAC. Clinically, the effect of desmoplasia is two-sided; on the negative side it is a hurdle in the diagnosis of PDAC because the fibrosis in cancer resembles that of CP. It is also believed that PSCs and pancreatic fibrosis are partially responsible for the therapy resistance in pancreatic cancer. On the positive side, a fibrotic pancreas is safer to operate on compared to a fatty and soft pancreas which is prone for postoperative pancreatic fistula. In this review the impact of pancreatic fibrosis on diagnosis of pancreatic cancer and surgical decisions are discussed from a clinical point of view.

The role of stroma in pancreatic cancer: diagnostic and therapeutic implications.

Pancreatic ductal adenocarcinoma (PDAC) is one of the five most lethal malignancies worldwide and survival has not improved substantially in the past 30 years. Desmoplasia (abundant fibrotic stroma) is a typical feature of PDAC in humans, and stromal activation commonly starts around precancerous lesions. It is becoming clear that this stromal tissue is not a bystander in disease progression. Cancer-stroma interactions effect tumorigenesis, angiogenesis, therapy resistance and possibly the metastatic spread of tumour cells. Therefore, targeting the tumour stroma, in combination with chemotherapy, is a promising new option for the treatment of PDAC. In this Review, we focus on four issues. First, how can stromal activity be used to detect early steps of pancreatic carcinogenesis? Second, what is the effect of perpetual pancreatic stellate cell activity on angiogenesis and tissue perfusion? Third, what are the (experimental) antifibrotic therapy options in PDAC? Fourth, what lessons can be learned from Langton's Ant (a simple mathematical model) regarding the unpredictability of genetically engineered mouse models?

Coronary CT angiography in step-and-shoot technique with 256-slice CT: impact of the field of view on image quality, craniocaudal coverage, and radiation exposure.

PURPOSE: To evaluate the effect of a small field of view (FOV) for step-and-shoot coronary computed tomography angiography (CCTA) on craniocaudal z-coverage per scan step, image quality, and radiation exposure. METHODS: 53 patients underwent prospectively ECG-gated CCTA on a 256-slice MDCT scanner using either a FOV > 250 mm (group 1, n = 29) or a FOV ≤ 250 mm (group 2, n = 24). Craniocaudal z-coverage was determined on coronal multiplanar reformations. Image noise, signal-to-noise ratio, contrast-to-noise ratio, and qualitative image parameters were assessed. Radiation dose was estimated from the dose length product and was standardized for a scan range from the main pulmonary artery to the diaphragm in order to make both groups comparable. RESULTS: Diagnostic image quality was achieved in 91.3% of the coronary artery segments of group 1 and 89.9% in group 2 (p = 0.201). There were no major differences in image noise, SNR, and CNR between both groups. A smaller FOV leads to an increase of craniocaudal coverage of a single CT scan step (r = -0.879; p ≤ 0.001). There was an increase of 23.8% of the mean z-coverage per scanned subvolume in group 2 (59.9 mm vs. 48.8mm). Radiation dose was significantly lower in group 2 (229 vs. 285 mGy cm, respectively). CONCLUSION: The use of a small transverse FOV for step-and-shoot CCTA at a wide detector CT scanner leads to an increased z-coverage. 2 scan volumes are enough to image the cardiac anatomy. Radiation dose is decreased without negative impact on image quality.

Adenocarcinomas of the esophagogastric junction are more likely to respond to preoperative chemotherapy than distal gastric cancer.

BACKGROUND: Preoperative chemotherapy has been shown to improve outcome of patients with adenocarcinoma of the esophagogastric junction (AEG) and gastric cancer (GC), and histopathologic response has been identified as an independent prognostic parameter in these patients. A recent meta-analysis has identified patients with AEG as benefiting more from preoperative chemotherapy than patients with GC. The aim of this retrospective analysis was to prove these findings in an experienced single-center large patient cohort because there are currently no recruiting prospective clinical trials. METHODS: In a single center, 551 patients underwent preoperative platin-based chemotherapy followed by oncologic surgery for locally advanced AEG and GC. Pretherapeutic clinical parameters were correlated with histopathologic response to preoperative chemotherapy. RESULTS: Histopathologic response (<10% of residual tumor) was found in 130 patients (24%) and was significantly correlated with overall survival (P<0.0001). Tumor localization at the esophagogastric junction (GE junction), lower baseline cT stage, and baseline cN0 stage were significantly associated with histopathologic response (P=0.034, P=0.015, and P=0.002, respectively). In subgroup analyses, the latter two predictive parameters were confirmed only for AEG (n=378) but not for other GC (n=173). AEG patients who were pretherapeutically staged as having cT3/4, cN0 disease (n=73) were identified as the subgroup with the highest rate of histopathologic response (48%). CONCLUSIONS: AEG is more likely to respond to preoperative chemotherapy than GC, a finding that might help identify patients who would benefit from preoperative chemotherapy.

Further experience with the free soleus perforator flaps using CT-angiography as a planning tool - a preliminary study.

INTRODUCTION: The soleus perforator flap is a soft tissue flap with minimal donor site morbidity however is not frequently utilised due to the unpredictability of the perforating vessel to serve as the vascular pedicle. We have trialed the use of CT-angiography as a planning tool to predict location, length, course, and calibre of the pedicle to make this a more reliable choice. METHODS: Twenty consecutive patients with intraoral squamous cell carcinomas were assessed with CT-angiography to examine the peroneal perforators before considering soleus flap raising. If a sizeable perforator could be visualised at the upper half of the lower leg, flap raising was carried out, and the result of the CT-angiography was compared with the intra-operative findings. RESULTS: CT-angiography allowed for visualisation of perforators measuring 1mm in diameter and could predict location, length and course of the vessel. Accordingly, eight of the 20 patients had to be excluded from flap raising due to missing, too fine or too far distally located perforators. Intra-operative findings corresponded well with the results of the CT-scans. CONCLUSION: CT-angiography is a useful tool for planning the soleus perforator flap and allows selection of the most suitable perforator making the use of this flap more reliable.

Initial performance characterization of a clinical noise-suppressing reconstruction algorithm for MDCT.

OBJECTIVE: The number of CT examinations is increasing relatively dramatically, hence the radiation dose of the associated population. Thus, there is a need for efficient reconstruction methods with dose reduction potential that also maintain the image quality. In this article, we present the initial performance evaluation of such a reconstruction algorithm (iDose, Philips Healthcare). MATERIALS AND METHODS: iDose is a hybrid iterative reconstruction algorithm that provides enhanced image quality while reducing the radiation dose compared with the current clinical standard reconstruction. To quantify the advantages of this algorithm in image quality and dose reduction, we compared iDose with the conventional filtered back projection algorithm. Furthermore, we describe the performance of iDose with respect to several image quality metrics. RESULTS: The HU values remain stable while employing iDose. With iDose, the noise is significantly reduced. This is reflected by an improvement in the contrast-to-noise ratio and in the noise power spectrum compared with a standard reconstruction. The measurements of the modulation transfer function confirm that, with iDose, there is no decline in spatial resolution. CONCLUSION: We conclude that iDose is an important tool in the reduction of radiation dose in CT. However, continuous efforts to reduce radiation dose should be pursued.

Sclerosing angiomatoid nodular transformation of the spleen presenting as a rapidly growing tumour in a patient with rectal cancer.

A patient with rectal cancer developed a rapidly growing splenic mass 2 years after cancer treatment. Since a metastatic process could not be ruled out, splenectomy was performed, and the tumour emerged as a sclerosing angiomatoid nodular transformation (SANT) of the spleen. SANT is a rare, recently recognised, non-neoplastic vascular lesion of the spleen that radiologically may be difficult to distinguish from vascular splenic lesions such as splenic hamartoma, haemangioma or littoral cell angioma. However, morphologically and immunohistochemically it is separated from those tumours by its unique nodular angiomatoid proliferation pattern. SANT is considered to be a benign lesion. This case is reported because of its important clinical impact for the differential diagnosis of splenic masses. Data regarding growth rates of these lesions are scarce and a growth progression as in this case, that finally led to the indication for splenectomy due to lingering suspicion of malignancy, is novel.

CT-navigated real-time ultrasonography: evaluation of registration accuracy for clinical application.

Ultrasound examination is a valuable diagnostic tool in almost all medical disciplines. However, the results are highly dependent on the experience and performance of the individual examiner and the technical conditions of the examination. Since computed tomography (CT) is not affected by these factors, the combination of real-time ultrasound images and previously compiled CT scans with identical cross-sections displayed simultaneously during transcutaneous ultrasonography could be advantageous. To evaluate the practical applicability and reliability of CT-supported transcutaneous ultrasonography, we examined 10 patients with a Real-Time Virtual Sonography Unit using a previously compiled CT scan as a reference. The results were evaluated by 10 sonographers with different levels of experience. By using the 3-point registration method almost identical ultrasound and CT cross-sections were displayed throughout the examination. However, there was a constant lateral and height deviation of the CT image detected. The crucial point is the correct and reliable referencing of the real-time ultrasound. In conclusion, the CT-navigated ultrasound seems not yet complete for clinical applications. Although helpful for training purposes, it is not accurate enough yet to play a role in routine clinical diagnostic work up.

Early metabolic response evaluation by fluorine-18 fluorodeoxyglucose positron emission tomography allows in vivo testing of chemosensitivity in gastric cancer: long-term results of a prospective study.

PURPOSE: We prospectively evaluated the predictive value of positron emission tomography using fluorine-18 fluorodeoxyglucose (FDG-PET) for in vivo testing of chemosensitivity in locally advanced gastric cancer using an a priori definition of metabolic response (a decrease of >35% of the standard uptake value). The goal of the study was the definition of biologically different groups of patients prior to or early during induction therapy, with special emphasis on FDG non-avid tumors. EXPERIMENTAL DESIGN: Based on our data, which was published in 2003, at least 36 patients with metabolic response or FDG non-avid tumors had to be recruited for an analysis of the group of FDG non-avid tumors with sufficient statistical power. Seventy-one patients (32 metabolic nonresponders, 17 metabolic responders, and 22 patients with FDG non-avid tumors) underwent FDG-PET at baseline. In FDG-avid tumors, FDG-PET was repeated 14 days after the initiation of chemotherapy. RESULTS: Metabolic responders (17 of 49) showed a high histopathologic response rate (69%) and a favorable prognosis (median survival not reached), whereas metabolic nonresponders (32 of 49) had a poor prognosis (median survival, 24.1 months) and showed a histopathologic response in 17%. The histopathologic response rate (24%) for FDG-PET non-avid patients showed no significant difference compared with FDG-avid nonresponders (P=0.72). Survival of FDG non-avid patients was 36.7 months (not significantly different from FDG-avid nonresponders, 24.1 months, P=0.46). CONCLUSION: In locally advanced gastric cancer, three different metabolic groups exist. Response and survival was predicted by PET in FDG-avid tumors. Metabolic response assessment was not possible in FDG non-avid tumors; however, due to unfavorable outcome, therapy modification might also be considered in FDG non-avid tumors.

Amelanotic esophageal malignant melanoma: case report and short review of the literature.

Malignant melanoma in the esophagus is a rare condition which has been described only occasionally in case reports or in larger series of patients with esophageal disease. We describe here the very rare case of a patient who presented initially with a 2-month history of dysphagia and weight loss which led to the endoscopic diagnosis of an unclear lesion in the distal esophagus. Biopsies were taken revealing positive immunohistochemical staining against HMB-45. As there were no signs of skin melanoma and there was an absence of pigmentation, a diagnosis of primary amelanotic malignant melanoma was made. Primary staging of the lesion was completed with computed tomography (CT), which revealed a locally advanced tumor with lymph node metastases at the lesser curvature of the stomach and celiac trunk. As there is still a lack of potential protocols for multimodal neoadjuvant treatment for this rare tumor entity, a palliative abdominothoracic esophagectomy with systemic lymphadenectomy and intrathoracic anastomosis was carried out. Due to an intraoperative R2 situation, clip marking was performed to allow postoperative radiotherapy. Two months postoperatively, the planning CT scan for radiotherapy revealed progression of the retroperitoneal tumor mass, which was enclosing the celiac trunk, renal vein, and superior mesenteric artery. Multiple new liver and lung metastases were also found. During the following weeks, the patient developed acute renal failure and was admitted for dialysis, and the planned radiotherapy was deferred. At the end of May 2007, 4 months after the primary diagnosis, the patient died due to acute renal failure.