CASE REPORT: The CT and 18F-FDG PET/CT appearance of primary renal malignant fibrous histiocytoma

Renal malignant fibrous histiocytoma (MFH) is a rare, primary renal tumour. Imaging findings of renal MFH, including ultrasound, CT and MRI, have, however, been reported. As to the best of our knowledge ¹⁸F-FDG PET/CT imaging of renal MFH has not been previously reported, we present the CT and ¹⁸F-FDG PET/CT appearance of a pathologically proven primary renal MFH.     

^18F-FDG PET/CT显像对肾细胞癌分级和临床分期及预后预测的价值

目的：评价PET/CT显像对于肾细胞癌恶性程度分级、临床分期及预后的价值。方法：回顾性分析46例临床诊断为肾细胞癌患者的PET/CT显像结果,与其他影像资料结果相比较,探讨其与肾细胞癌分级、临床分期及预后的关系。结果：46例患者中,经手术病理确诊为肾细胞癌者37例,其余9例因PET/CT显像发现有转移病灶放弃手术。PET/CT检查结果真阳性41例,假阴性5例,敏感度为89.1%,其他影像资料敏感度为84.8%。37例手术患者中,3级肾细胞癌病理分组间SUV差异均有统计学意义,P值分别为0.034、0.012和0.021。17例死亡病例,平均生存期为9个月,最大SUV越高,患者的生存期相对就越短。结论：PET/CT显像结果与肾细胞癌分级有关,分级越高,阳性率越高;PET/CT显像对于肾细胞癌临床分期及预后亦有重要价值。     

Sigmoid colon metastasis from sarcomatoid renal cell carcinoma

The sarcomatoid histological type of renal cell carcinoma is a clinically aggressive variant of parenchymal tumor, typically resistant to systemic treatment. We report the case of a 65-year-old female patient who had undergone a left radical nephrectomy for a sarcomatoid renal cell carcinoma together with enucleation of a mass of the right kidney and a contralateral nodule diagnosed as clear cell carcinoma. One year later lung, adrenal and sigmoid colon metastases from sarcomatoid renal cell carcinoma were detected and the patient was started on systemic immunotherapy with interleukin-2 and interferon-alpha. Computed tomography showed marked disease progression and the patient died 3 weeks later. Sigmoid colon metastasis from a primary sarcomatoid renal cell carcinoma has never been described in the literature.     

Positron emission tomography/ultrasound fusion technique in patients with malignant melanoma

¹⁸F‐fluorodeoxyglucose positron emission tomography (FDG‐PET)/CT is commonly used to assess tumour recurrence in high‐risk patients with malignant melanoma (MM). However, results can be ambiguous either because of the CT's insufficient soft‐tissue contrast or non‐specific FDG accumulation caused by inflammation. Ultrasound (US) can provide additional morphologic information that is superior to CT. For precisely combining PET and US findings, we used a real‐time fusion technique based on navigated US (PET/US fusion). Here, we describe our results from patients where PET/US fusion proved helpful in differentiating unclear PET/CT findings. This fusion technique is likely to be helpful for decision making in MM patients and biopsy guidance.     

Prevalence of non 18F‐fluorodeoxyglucose‐avid incidental findings of clinical significance on whole body positron emission tomography/computed tomography: A review of 500 consecutive cases

Introduction

The prevalence of incidental ¹⁸F‐fluorodeoxyglucose (FDG)‐avid findings on positron emission tomography–computed tomography (PET/CT) has been extensively described. Few studies, however, have assessed the prevalence and significance of non‐FDG‐avid findings; pathology that is identified on review of the low‐dose, non‐contrast CT. The aim of this study was to determine the overall prevalence of non FDG‐avid incidental findings on PET/CT and the prevalence of ‘clinically significant’ non FDG‐avid pathology.

Methods

Five hundred consecutive whole body PET/CT studies performed in 2016 at a university affiliated tertiary hospital were retrospectively reviewed by two radiologists experienced in reporting PET/CT. Findings were categorized according to potential clinical relevance, and a targeted follow‐up of clinically significant incidental findings was performed.

Results

Incidental findings were encountered in 463 of 500 (92.6%) patients. In 226 patients, these findings had been detected on previous imaging studies, with unknown incidental findings present in 237 of 500 (47.4%) patients. 113 of 500 (22.6%) patients had non‐avid incidental findings of potentially major clinical significance, and in 35 patients (7.0%) these findings were considered previously unknown. The most common non‐avid findings of potentially major significance were pulmonary nodules (6 mm or larger), moderate or large size pleural effusions, and vascular aneurysms. Unknown incidental findings of potentially major clinical significance were significantly higher in patients imaged for melanoma staging (P= 0.004).

Conclusion

The prevalence of incidental findings of clinical significance that do not accumulate FDG in PET/CT is not insignificant. Routine systematic review of the low‐dose CT is required to avoid missing potentially clinically important findings, in particular pleural effusions, vascular aneurysms and metastatic pulmonary nodules.     

Impact of FDG-PET on lung cancer delineation for radiotherapy

Purpose: The purpose of this study is to assess the impact of fused diagnostic F‐18 2‐fluoro‐2‐deoxy‐D‐glucose (FDG) positron emission tomography (PET)/computed tomography (CT) and planning FDG‐PET/CT scans on voluming of lung cancer for radiotherapy. Methods: Five radiation oncologists (ROs), five radiation oncology trainees and a radiologist contoured five cases of non‐small cell lung cancer. The CT alone, the diagnostic FDG‐PET/CT and planning FDG‐PET/CT each registered to the CT, were used to contour three volumes. The concordance index (CI) was used to compare each volume with a reference RO. Results: Although there was considerable inter‐observer variability in CT contouring, there was no significant difference between mean volumes of the gross tumour volume for the RO and radiation oncology trainees using any technique. There was no increase in CI with the addition of PET/CT, either diagnostic or planning, for the RO. However, the volumes of the radiation oncology trainees showed a significant increase in CI from 65.8% with CT alone to 68.0% and 72.3% with diagnostic PET/CT and planning PET/CT, respectively (P = 0.028). Mean variation at the tumour/mediastinum interface was significantly reduced with addition of registered PET/CT. Conclusions: The concordance of RO with the reference RO did not significantly increase with use of integrated FDG PET/CT images. However, the contouring of radiation oncology trainees' became more concordant with the reference.     

核医学正电子断层显像在肾肿瘤患者术前诊断中的作用

目的探讨PET在肾肿瘤术前诊断中作用。方法回顾性分析134例肾肿瘤患者PET图像。134例肾肿瘤术前评估患者中,32例行常规氟-18脱氧葡萄糖(18F-fluorodeoxyglucose,18F-FDG)PET或PET/CT显像(以下简称FDG-PET),51例行FDG-PET双时相显像,51例1周内分别行FDG-PET及碳-11乙酸盐(11C-acetate,AC)PET或PET/CT(以下简称AC-PET)双核素检查。收集其临床资料和影像检查结果。以病理结果为金标准。结果 FDG-PET对肾原发恶性肿瘤总的诊断准确率为48.5%,阳性预测值为96.3%,对透明细胞癌诊断准确率最低,为28.6%。对肾盂癌及其他恶性肿瘤诊断准确率为92.9%和75.0%。AC-PET对透明细胞癌诊断准确率93.5%。FDG-PET双时相显像60.0%阳性病灶标准摄取值(standard uptake value,SUV)升高,2例阴性病灶变为阳性。20例PET检查前其他检查发现肾外病灶的患者,检查后排除4例,并新发现6例患者肾外转移病灶。结论 FDG-PET检查对肾盂癌及其他恶性肿瘤诊断准确性高,对肾实质肿瘤诊断能力差,对肾肿瘤患者术前分期有帮助。AC-PET可弥补FDG-PET的不足。FDG-PET双时相显像不能从根本上解决FDG-PET对肾肿瘤诊断假阴性的问题。     

Laparoscopic extraperitoneal para-aortic lymphadenectomy in locally advanced cervical cancer: a prospective correlation of surgical findings with positron emission tomography/computed tomography findings

BACKGROUND:

Failure to detect metastasis to para‐aortic nodes in patients with locally advanced cervical cancer leads to suboptimal treatment. No previous studies have prospectively compared positron emission tomography (PET)/computed tomography (CT) with laparoscopic extraperitoneal staging in the evaluation of para‐aortic lymph nodes.

METHODS:

Sixty‐five patients were enrolled; 60 were available for analysis. Patients with stage IB2‐IVA cervical cancer without evidence of para‐aortic lymphadenopathy on preoperative CT or magnetic resonance imaging (MRI) were prospectively enrolled. All patients underwent preoperative PET/CT. Laparoscopic extraperitoneal lymphadenectomy was performed from the common iliac vessels to the left renal vein.

RESULTS:

The median age at diagnosis was 48 years (range, 23‐84). The median operative time was 140 minutes (range, 89‐252). The median blood loss was 22.5 mL (range, 5‐150). The median length of hospital stay was 1 day (range, 0‐4). The median number of lymph nodes retrieved was 11 (range, 1‐39). Fourteen (23%) patients had histopathologically positive para‐aortic nodes. Of the 26 patients with negative pelvic and para‐aortic nodes on PET/CT, 3 (12%) had histopathologically positive para‐aortic nodes. Of the 27 patients with positive pelvic but negative para‐aortic nodes on PET/CT, 6 (22%) had histopathologically positive para‐aortic nodes. The sensitivity and specificity of PET/CT in detecting positive para‐aortic nodes when nodes were negative on CT or MRI were 36% and 96%, respectively. Eleven (18.3%) patients had a treatment modification based on surgical findings.

CONCLUSIONS:

Laparoscopic extraperitoneal para‐aortic lymphadenectomy is safe and feasible. Surgical staging of patients with locally advanced cervical cancer should be considered before planned radiation and chemotherapy. Cancer 2011. © 2010 American Cancer Society.     

Splenic scintigraphy for further differentiation of unclear 68Ga‐DOTATOC‐PET/CT findings: Strengths and limitations

Splenic scintigraphy has been described to be a powerful tool in unclear ⁶⁸ Ga‐DOTATOC‐PET/CT findings, allowing differentiation between somatostatin receptor (Sst)‐positive tissue deriving from neuroendocrine tumour (NET) and functioning splenic tissue. However, our own experiences sometimes show a lack of identification on splenic scintigraphy, especially in small lesions, leading to uncertainties regarding the safe identification of NET or splenic tissue. Here, we report on 10 cases with ⁶⁸Ga‐DOTATOC‐PET/CT and ^99mTc‐heat‐denaturated red blood cell (HDRBC) scintigraphy and we illustrate the strengths and limitations of ^99mTc‐HDRBC scintigraphy in this context.     

Ability of integrated positron emission and computed tomography to detect significant colonic pathology

BACKGROUND:

The ability of integrated positron emission tomography and computed axial tomography (PET‐CT) to detect colonic pathology is not fully defined. The purpose of this study was to assess the ability of PET‐CT to detect colonic pathology and to determine the significance of (¹⁸F)2‐fluoro‐2‐deoxyglucose (¹⁸F‐FDG) activity noted incidentally in the colon on PET‐CT.

METHODS:

Records for all patients who underwent PET‐CT and colonoscopy at our institution were reviewed. Patients with history of colonic malignancy or colon surgery were excluded.

RESULTS:

Fifty‐eight patients had incidental colonic ¹⁸F‐FDG activity on PET (Group A) and 272 had none (Group B). In Group A, 65% of patients had pathologic findings detected on colonoscopy that corresponded to the site of PET activity. Standardized uptake value (SUV) readings were not helpful in distinguishing true‐positives from false‐positives. In Group B, 11.8% of patients were found to have significant colonic findings. Lesions not detected by PET‐CT included 4 colon cancers, 7 advanced adenomas, and 10 patients with colonic lymphoma. Overall, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET‐CT for detecting significant pathology were 53%, 93%, 65%, 89%, and 85%, respectively. For detecting colon cancer and adenomas 10 mm or more, the sensitivity, specificity, PPV, NPV, and accuracy of PET‐CT were 72%, 90%, 45%, 96%, and 88%, respectively.

CONCLUSIONS:

Incidental colonic activity detected by PET‐CT warrants further evaluation with colonoscopy. However, negative PET‐CT does not rule out significant colonic pathology including colon cancer, advanced adenomas, or lymphoma. Cancer 2010. © 2010 American Cancer Society.     

A comparison of positron emission tomography (pet) utilizing C-11 methionine and computerized-tomography in the diagnosis of renal-cell adenocarcinoma

Positron emission tomography (PET) is a radionuclide method that quantifies physiological and metabolic parameters in vivo. PET with L-methyl-C-11-methionine as a tracer was performed in 13 patients with advanced renal cell carcinoma and twenty-two lesions were evaluated. Two of 13 patients still had their primary renal tumours. The PET images of all the patients showed a good correlation with the computerized tomography (CT) images, and detected not only the primary tumour but also metastases. PET utilizing 11-methionine was efficient in visualizing metastatic lesions in the thorax. The conclusion of this pilot study is that the PET technique with C-11-methionine as a tracer can be used in the diagnosis of advanced renal cell adenocarcinoma to visualize and characterize the primary renal tumour and its metastases in vivo.     

18F-FDG PET/CT显像对肾细胞癌分级和临床分期及预后预测的价值

目的:评价PET/CT显像对于肾细胞癌恶性程度分级、临床分期及预后的价值。方法:回顾性分析46例临床诊断为肾细胞癌患者的PET/CT显像结果,与其他影像资料结果相比较,探讨其与肾细胞癌分级、临床分期及预后的关系。结果:46例患者中,经手术病理确诊为肾细胞癌者37例,其余9例因PET/CT显像发现有转移病灶放弃手术。PET/CT检查结果真阳性41例,假阴性5例,敏感度为89.1%,其他影像资料敏感度为84.8%。37例手术患者中,3级肾细胞癌病理分组间SUV差异均有统计学意义,P值分别为0.034、0.012和0.021。17例死亡病例,平均生存期为9个月,最大SUV越高,患者的生存期相对就越短。结论:PET/CT显像结果与肾细胞癌分级有关,分级越高,阳性率越高;PET/CT显像对于肾细胞癌临床分期及预后亦有重要价值。     

肾脏黏液性小管状和梭形细胞癌研究进展

肾脏黏液性小管状和梭形细胞癌(mucinous tubular and spindlecell carcinoma,MTSCCa)是新确定一种罕见的低度恶性肾上皮性肿瘤。多见于青年女性,临床上无明显症状。以往常被诊断为梭形细胞(肉瘤样)肾细胞癌或不能分类的肾细胞癌。大体肿物界限清楚,切面实性、灰白色。组织学特点是肿瘤细胞排列成管状和实性梁索状漂浮于黏液性基质中,Alcianblue染色阳性。免疫组化显示复合性免疫表型。临床预后好,可复发并具有潜在远处转移的可能,应重视与其他肾脏良恶性肿瘤(后肾腺瘤、肉瘤样癌和集合管癌等)相鉴别。     

Cardiac tamponade in multiple myeloma – A pictorial case review of FDG PET/CT findings

Pericardial involvement of multiple myeloma is a rare and late‐stage complication, with only a few cases reported in the literature. PET/CT has demonstrated a growing role in the diagnosis and follow‐up of patients with multiple myeloma. We present a case of pericardial multiple myeloma in a patient with relapsed/refractory disease, showcasing previously unpublished FDG PET/CT findings.     

Value of fused positron emission tomography CT in detecting primaries in patients with primary unknown cervical lymph node metastasis

Objective: Identification of the primary tumour can prolong the life expectancy of patients with primary unknown cervical lymph node metastasis (PUCLNM) through targeted therapy. This study investigated the value of 18F‐fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET‐CT) at identifying primaries in patients with PUCLNM. Methods: Twenty‐seven patients (21 males and 6 females, median age 48.2 ± 16.3, age range 30–73) with PUCLNM underwent FDG PET‐CT to search for the primary tumour, which could not be detected by conventional diagnostic modalities. The results were analysed and correlated with either pathological findings or clinical follow up. Results: Pathological FDG uptake suspicious for the primary was detected in 13 cases, while the primary tumour remained occult in 14 cases. Eleven of 13 patients with suspected primaries were confirmed by histological findings. One with a coexisting second tumour and three with unexpected distant metastases were found in patients with confirmed primaries. The most common primary location in patients with PUCLNM found in our study was nasopharynx. In those 14 patients with negative FDG PET‐CT results, only one patient had a primary malignancy that was proven histologically after endoscopy with biopsy during a period of clinical follow up. The sensitivity, specificity, accuracy and positive predictive values of FDG PET‐CT were 91.7, 86.7, 88.9 and 84.6%, respectively. Conclusion: FDG PET‐CT is a useful tool to help search for unknown primaries in patients with cervical lymph node metastasis and has an acceptable diagnostic yield for the detection of distant malignancies.     

Evaluation of pulmonary nodules and lung cancer with one‐inch crystal gamma coincidence positron emission tomography/CT versus dedicated positron emission tomography/CT

Dedicated positron emission tomography (PET)/CT scanners using BGO and related detectors (d‐PET) have become standard imaging instruments in many malignancies. Hybrid gamma camera systems using NaI detectors in coincidence mode (g‐PET) have been compared to d‐PET but reported usefulness has been variable when gamma cameras with half‐inch to three‐fourth‐inch thick crystals have been used without CT. Our aim was to compare g‐PET with a 1‐in.‐thick crystal and inbuilt CT for lesion localization and attenuation correction (g‐PET/CT) and d‐PET/CT in patients presenting with potential and confirmed lung malignancies. One hour after ¹⁸F‐fluorodeoxyglucose (FDG), patients underwent BGO d‐PET/CT from jaw to proximal thigh. This was followed by one to two bed position g‐PET/CT 194 ± 27 min after FDG. Each study pair was independently analysed with concurrent CT. d‐PET/CT was interpreted by a radiologist experienced in both PET and CT, and g‐PET/CT by consensus reading of an experienced PET physician and an experienced CT radiologist. A TNM score was assigned and studies were then unblinded and compared. Fifty‐seven patients underwent 58 scan pairs over 2 years. Eighty‐nine per cent concordance was shown between g‐PET/CT and d‐PET/CT for the assessment of intrapulmonary lesions, with 100% concordance for intrapulmonary lesions >10 mm (36 of 36). Eighty‐eight per cent (51 of 58) concordance was shown between g‐PET/CT and d‐PET/CT for TNM staging. Coincidence imaging using an optimized dual‐head 1‐in.‐thick crystal gamma camera with inbuilt CT compares reasonably well with dedicated PET/CT for evaluation of indeterminate pulmonary lesions and staging of pulmonary malignancies and may be of some value when d‐PET/CT is not readily available.     

Clonal divergence and genetic heterogeneity in clear cell renal cell carcinomas with sarcomatoid transformation

BACKGROUND: Approximately 5% of clear cell renal cell carcinomas contain components with sarcomatoid differentiation. It has been suggested that the sarcomatoid elements arise from the clear cell tumors as a consequence of clonal expansions of neoplastic cells with progressively more genetic alterations. Analysis of the pattern of allelic loss and X-chromosome inactivation in both the clear cell and sarcomatoid components of the same tumor allows assessment of the genetic relationship of these tumor elements. METHODS: The authors of the current study examined the pattern of allelic loss in clear cell and sarcomatoid components of renal cell carcinomas from 22 patients who had tumors with both components. DNA samples were prepared from formalin-fixed, paraffin-embedded renal tissue sections using laser-capture microdissection. Five microsatellite polymorphic markers for putative tumor suppressor genes on 5 different chromosomes were analyzed. These included D3S1300 (3p14), D7S522 (7q31), D8S261 (8p21), D9S171 (9p21), and TP53 (17p13). In addition, X-chromosome inactivation analysis was performed in 14 tumors from female patients. RESULTS: The clear cell components showed loss of heterozygosity (LOH) at the D3S1300, D7S522, D8S261, D9S171, and TP53 loci in 18% (4/22), 18% (4/22), 50% (10/20), 15% (3/20), and 20% (4/20) of informative cases, respectively. LOH in the sarcomatoid components was seen at the D3S1300, D7S522, D8S261, D9S171, and TP53 loci in 18% (4/22), 41% (9/22), 70% (14/20), 35% (7/20), and 20% (4/20) of informative cases, respectively. Six cases demonstrated an LOH pattern in the clear cell component that was not seen in the sarcomatoid component. Different patterns of allelic loss were seen in the clear cell and sarcomatoid components in 15 cases. Clonality analysis showed the same pattern of nonrandom X-chromosome inactivation in both clear cell and sarcomatoid components in 13 of the 14 cases studied. One case showed a random pattern of X-chromosome inactivation. CONCLUSION: X-chromosome inactivation analysis data suggest that both clear cell and sarcomatoid components of renal cell carcinomas are derived from the same progenitor cell. Different patterns of allelic loss in multiple chromosomal regions were observed in clear cell and sarcomatoid components from the same patient. This genetic heterogeneity indicates genetic divergence during the clonal evolution of renal cell carcinoma.     

18F‐Fluorodeoxyglucose positron emission tomography/computed tomography for the detection of recurrent bone and soft tissue sarcoma

BACKGROUND:

The clinical utility of modern hybrid imaging modalities for detecting recurrent bone or soft tissue sarcoma remains to be determined. In this report, the authors present a clinical study on the diagnostic accuracy and incremental value of integrated ¹⁸F‐fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F‐FDG PET/CT) in patients with a history of sarcoma who have clinically suspected disease recurrence.

METHODS:

Forty‐three patients who had a history of bone or soft tissue sarcoma and had documented complete remission underwent ¹⁸F‐FDG PET/CT. Image analysis was performed independently for ¹⁸F‐FDG PET (n = 43) and for contrast‐enhanced spiral CT (CE‐CT) (n = 30) by 2 separate readers, whereas combined ¹⁸F‐FDG PET/CT (n = 43) images were analyzed in consensus by both readers. Imaging findings were rated on a 5‐point scale and finally were reported as malignant, benign, or equivocal. Imaging findings were validated either by histopathology (n = 24) or by clinical follow‐up (n = 19).

RESULTS:

¹⁸F‐FDG PET/CT had greater sensitivity and specificity compared with CE‐CT alone (94% and 92% vs 78% and 67%, respectively), resulting in significantly greater accuracy (93% vs 73%; P = .03). ¹⁸F‐FDG PET/CT was particularly superior regarding detection of local recurrence or soft tissue lesions (sensitivity and specificity: 83% and 100% vs 50% and 100%, respectively) or bone metastases (100% and 100% vs 85% and 88%, respectively).

CONCLUSIONS:

¹⁸F‐FDG PET/CT had greater diagnostic accuracy in the detection of recurrent bone or soft tissue sarcoma compared with CE‐CT alone. The detection of local recurrence was the most evident advantage of ¹⁸F‐FDG PET/CT over CE‐CT. Cancer 2013. © 2012 American Cancer Society.     

Post-treatment (not interim) positron emission tomography-computed tomography scan status is highly predictive of outcome in mantle cell lymphoma patients treated with R-HyperCVAD

BACKGROUND:

Although convincing data exist regarding the prognostic utility of positron emission tomographic (PET)‐computed tomographic (CT) imaging in Hodgkin lymphoma and diffuse large B‐cell lymphoma, its prognostic utility both during treatment and immediately after treatment have not been systematically evaluated in a large mantle cell lymphoma (MCL) patient cohort to support its use in clinical practice.

METHODS:

The authors conducted a retrospective cohort study to examine the prognostic utility of PET‐CT imaging in a uniform MCL patient cohort undergoing dose‐intensive chemotherapy (R‐HyCVAD) in the frontline setting. The primary study endpoints were progression‐free survival (PFS) and overall survival (OS). PET‐CT images were centrally reviewed for the purposes of this study using standardized response criteria.

RESULTS:

Fifty‐three patients with advanced stage MCL with PET‐CT data were identified. With median follow‐up of 32 months, 3‐year PFS and OS estimates were 76% (95% confidence interval [CI], 64%‐84%) and 84% (95% CI, 72%‐90%), respectively. Interim PET‐CT status was not associated with PFS (hazard ratio [HR], 0.9; 95% CI, 0.3‐2.7; P = .8) or OS (HR, 0.6; 95% CI, 0.1‐2.9; P = .5). Post‐treatment PET‐CT status was statistically significantly associated with PFS (HR, 5.2; 95% CI, 2.0‐13.6; P = .001) and trended toward significant for OS (HR, 2.8; 95% CI, 0.8‐9.6; P = .07).

CONCLUSIONS:

These data do not support the prognostic utility of PET‐CT in pretreatment and interim treatment settings. A positive PET‐CT after the completion of therapy identifies a patient subset with an inferior PFS and a trend toward inferior OS. Cancer 2012;3565–3570. © 2011 American Cancer Society.     

Comparison of CT and positron emission tomography/CT coregistered images in planning radical radiotherapy in patients with non‐small‐cell lung cancer

Imaging with F‐18 fluorodeoxyglucose positron emission tomography (PET) significantly improves lung cancer staging, especially when PET and CT information are combined. We describe a method for obtaining CT and PET images at separate acquisitions, which allows coregistration and incorporation of PET information into the radiotherapy (RT) planning process for non‐small‐cell lung cancer. The influence of PET information on RT planning was analysed for 10 consecutive patients. Computed tomography and PET images were acquired with the patient in an immobilization device, in the treatment position. Using specially written software, PET and CT data were coregistered using fiducial markers and imported into our RT planning system (Cadplan version 6). Treatment plans were prepared with and without access to PET/CT coregistered images and then compared. PET influenced the treatment plan in all cases. In three cases, geographic misses (gross tumour outside planning target volume) would have occurred had PET not been used. In a further three cases, better planning target volume marginal coverage was achieved with PET. In four patients, three with atelectasis, there were significant reductions in V20 (percentage of the total lung volume receiving 20 Gy or more). Use of coregistered PET/CT images significantly altered treatment plans in a majority of cases. This method could be used in routine practice at centres without access to a combined PET/CT scanner .