Atypical metastatic lung cancer of the right ventricle on FDG PET/CT

Although primary cardiac tumours are extremely uncommon, secondary tumours or cardiac metastasis are not. We present a 68-year-old gentleman with squamous cell carcinoma of the right lower lobe with bony metastasis to the right clavicle who was treated with radiotherapy to the lung and clavicle as well as combination immunotherapy (Pembrolizumab) and chemotherapy (Carboplatin/Paclitaxel). Despite completing the above treatment regime, ¹⁸F-FDG PET/CT scan showed progression with two new sites of metastasis including a focus in the lateral wall of the right ventricle which correlate to a soft tissue density mass on CT as well as a FDG avid mass in the left masseter. Identification of cardiac lesions with ¹⁸F-FDG PET/CT maybe challenging with routine preparation due high physiological FDG uptake in the myocardium and significant variability, nevertheless, focal FDG uptake in the heart should be carefully assessed for the possibility of cardiac metastasis.     

The response of FDG uptake to immunosuppressive treatment on FDG PET/CT imaging for cardiac sarcoidosis

Background

Immunosuppression is used to treat cardiac sarcoidosis, despite limited data. FDG PET/CT is used for detecting cardiac inflammation in patients with CS, yet there is variability in interpretation of FDG PET/CT. Our aim was to compare quantitative and qualitative interpretation of FDG PET/CT for CS in defining the FDG response to immunosuppression.

Methods and Results

Patients with CS (N = 43 total studies from 17 patients) had serial FDG PET/CT studies before/after immunosuppression. FDG uptake was analyzed qualitatively (visually; FDG-positive segments) and quantitatively (SUVmax; cardiac metabolic volume and activity (CMV, CMA); volume above SUV thresholds 2.7 and 4.1 g/mL). Complete resolution of FDG uptake was common using CMA (10/17), CMV (10/17), but a 2.7 g/mL SUV threshold (13/17) and SUVmax (14/17) were more likely to define partial responses. In six patients imaged after a reduction in immunosuppression, 4/6 had a rebound quantitative FDG uptake.

Conclusions

Quantitative interpretation of FDG PET/CT in CS can detect changes in FDG uptake in response to immunosuppression. Further studies are needed to see if quantitative changes in FDG uptake are associated with improved outcomes.

     

Diagnostic value of quantitative assessment of cardiac <Superscript>18</Superscript>F-fluoro-2-deoxyglucose uptake in suspected cardiac sarcoidosis

Objective

The identification of cardiac sarcoidosis is challenging as there is no gold standard consensually admitted for its diagnosis. The aim of this study was to evaluate the diagnostic value of the assessment of cardiac dynamic ¹⁸F-fluoro-2-deoxyglucose positron emission tomography (¹⁸F-FDG PET/CT) and net influx constant (Ki) in patients suspected of cardiac sarcoidosis.

Methods

Data obtained from 30 biopsy-proven sarcoidosis patients suspected of cardiac sarcoidosis who underwent a 50-min list-mode cardiac dynamic ¹⁸F-FDG PET/CT after a 24 h high-fat and low-carbohydrate diet were analyzed. A normalized coefficient of variation of quantitative glucose influx constant, calculated as the ratio: standard deviation of the segmental Ki (min^?1)/global Ki (min^?1) was determined using a validated software (Carimas^® 2.4, Turku PET Centre). Cardiac sarcoidosis was diagnosed according to the Japanese Ministry of Health and Welfare criteria. Receiving operating curve analysis was performed to determine sensitivity and specificity of cardiac dynamic ¹⁸F-FDG PET/CT analysis to diagnose cardiac sarcoidosis.

Results

Six out of 30 patients (20%) were diagnosed as having cardiac sarcoidosis. Myocardial glucose metabolism was significantly heterogeneous in patients with cardiac sarcoidosis who showed significantly higher normalized coefficient of variation values compared to patients without cardiac sarcoidosis (0.513?±?0.175 vs. 0.205?±?0.081; p?=?0.0007). Using ROC curve analysis, we found a cut-off value of 0.38 for the diagnosis of cardiac sarcoidosis with a sensitivity of 100% and a specificity of 91%.

Conclusions

Our results suggest that quantitative analysis of cardiac dynamic ¹⁸F-FDG PET/CT could be a useful tool for the diagnosis of cardiac sarcoidosis.

     

Use of integrated FDG-PET/CT in sarcoidosis

We studied five patients with mediastinal lymph node enlargement suggestive of malignant lymphoma, lung cancer, or sarcoidosis. Integrated [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) was performed on all patients. Sarcoidosis can be a pitfall in PET/CT imaging, which may lead to false-positive results of malignancy. Increased FDG uptake in mediastinal lymph nodes is often comparable with malignant lymphoma or lymph node metastases. Histological confirmation of the lesions should be mandatory, except for patients in whom sarcoidosis can be accurately confirmed by other diagnostic methods.     

The role of serial FDG PET for assessing therapeutic response in patients with cardiac sarcoidosis

Background

The purpose of this study was to determine the feasibility of serial quantitative 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET) to monitor the response of cardiac sarcoidosis to treatment.

Methods and Results

A total of 38 PET scan intervals (54 PET scans) were obtained in 16 patients with cardiac sarcoidosis who underwent serial FDG PET during treatment. FDG-avid lesions of the heart were interpreted quantitatively using 4 PET parameters: maximum standardized uptake value (SUVmax), partial volume corrected mean standardized uptake value (SUVmean), partial volume corrected metabolic volume product (MVP), and global metabolic volume product (gMVP). Clinical response to treatment (improved, stable, or progressive disease) was evaluated by clinical symptoms, NYHA class, and EKG in all the patients. SUVmax, SUVmean, MVP, and gMVP had significantly decreased value on repeat PET in patients who were either stable or showed clinical improvement between two serial PET scans, while none of them had significant change on repeat PET in patients who were clinically worse. Correlation analysis between PET findings and clinical assessment revealed that the changes of SUVmax and SUVmean on repeat PET were negatively correlated with patient’s clinical outcome.

Conclusion

Our results indicated that serial FDG PET is feasible to determine the extent of disease activity and to quantitatively assess the response of cardiac sarcoidosis to therapy.

     

Right ventricular 18F-FDG uptake is an important indicator for cardiac involvement in patients with suspected cardiac sarcoidosis

Purpose

Cardiac sarcoidosis is most commonly found in the left ventricular (LV) free wall. Presence in the right ventricle (RV) is less common but might be useful for detecting cardiac involvement of sarcoidosis. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET has been used to detect LV regions with cardiac sarcoidosis. However, the same has not been done for RV involvement. The aims of the current study were to evaluate RV ¹⁸F-FDG uptake and its relationship to the distribution of LV wall ¹⁸F-FDG-positive segments in the LV, and to evaluate whether patients with positive RV ¹⁸F-FDG uptake met the 1993 diagnostic criteria of the Japanese Ministry of Health and Welfare (JMHW) guidelines regarding sarcoidosis with suspected cardiac involvement.

Method

Fifty-nine biopsy-proven extra-cardiac sarcoidosis patients (age 56.1 ± 14.7 years) with suspected cardiac involvement based on abnormal electrocardiography or echocardiography findings underwent fasting ¹⁸F-FDG PET or PET/CT. The LV wall was divided into 17 segments and RV uptake was also evaluated.

Result

Among 59 patients, 35 (59.3 %) showed some abnormal ¹⁸F-FDG uptake in the RV and/or LV wall. With respect to the RV wall, 13 (22.0 %) showed abnormal ¹⁸F-FDG uptake. The number of LV-involved segments was 4.8 ± 2.4 in the patients with RV ¹⁸F-FDG uptake, which was significantly higher than in the patients without RV uptake, 1.8 ± 2.2 (P < 0.0001). Patients with RV uptake more frequently met the diagnostic criteria of the 1993 JMHW guidelines (n = 27), than did those without RV uptake (84.6 vs. 34.8 %, P = 0.0033).

Conclusion

¹⁸F-FDG PET identified RV involvement less frequently than LV involvement in this study population. However, patients who had RV uptake showed a greater number of LV-involved segments and met the JMHW diagnostic criteria more frequently. Although RV uptake is less frequent, ¹⁸F-FDG RV uptake may be useful in diagnosing cardiac involvement in sarcoidosis.

Clinical trial registration

UMIN000006533.     

22例结节病18F—FDGPET／CT影像学特征分析

目的总结结节病患者胸部及胸外病变18F—FDGPET／CT影像特征,评价其在结节病诊断中的意义。方法回顾分析2007年8月至2009年11月间,符合国内结节病诊断标准、并经病理检查和随访证实的结节病患者22例资料,其中男10例,女12例。分析18F—FDGPET／CT图像所示胸部及胸外病变。根据两侧肺门淋巴结是否为对称性增大（CT图像）和对称性放射性浓聚（PET图像）分为典型和不典型结节病两种类型。数据统计采用非参数McNemar检验、独立分组t检验和Fisher精确检验。结果PET和cT图像所示典型、不典型结节病分别为18例、4例和12例、10例,两者间组成比例差异有统计学意义（P=0．031）。CT所示不典型结节病,PET图像均显示两侧肺门淋巴结有累及,表现为对称性或不对称性放射性浓聚。胸外淋巴结以盆、腹腔淋巴结累及较常见,发生率为54．5％（12／22）;结外脏器累及最常见于肺,为86．4％（19／22）。结论结节病的胸部和胸外病变在18F—FDGPET／CT图像上有一定的特征性,有助于cT表现不典型的结节病的诊断。     

Usefulness of 18F-FDG PET for diagnosis of cardiac sarcoidosis]

Cardiac sarcoidosis, the main cause of death among patients with sarcoidosis, frequently becomes clinically apparent when the disease is far advanced. To evaluate the usefulness of the 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in detecting cardiac sarcoidosis, 18F-FDG PET was performed in 16 patients with sarcoidosis (13 female, 63 +/- 12 yrs), compared with scintigraphic findings of 99mTc-MIBI and 67Ga. Ten of 16 patients were considered to have cardiac complications on clinical grounds with tissue confirmation such as positive endomyocardial biopsy, severe ventricular arrhythmia, more than second degree atrioventricular block, and echocardiographically proven ventricular dysfunction. Among these patients with cardiac complications, abnormal myocardial uptake of FDG were observed in all (100%), which confirms significantly higher frequency compared to 67Ga scintigraphy (50%) (abnormality of 99mTc-MIBI SPECT were observed in 80%). Although abnormal FDG accumulations were observed in region with decreased uptake of 99mTc-MIBI in many cases, localization of regional abnormality of each tracer was frequently independent. This discrepancy may reflect inflammatory and degenerative process of myocardium in cardiac sarcoidosis. 18F-FDG PET is thought to be a useful noninvasive method in detecting cardiac involvement of sarcoidosis and may provide a useful information on the activity of the disease.     

Effectiveness of prolonged fasting 18f-FDG PET-CT in the detection of cardiac sarcoidosis

Background  

The Japanese Ministry of Health and Welfare guidelines (JMHWG) are currently the standard used to diagnose cardiac sarcoidosis. JMHWG incorporate ⁶⁷Gallium scintigraphy as a minor criterion, while fasting ¹⁸fluorine-2-fluro-2-deoxy-d-glucose (FDG) PET is not included. As there is no published data comparing the accuracy of prolonged fasting FDG PET-CT (PF-PET) and Gallium scintigraphy for detecting active cardiac sarcoidosis, we sought to compare these two modalities.     

Current clinical use of 18FDG-PET/CT in patients with thoracic and systemic sarcoidosis

Purpose

This study assessed the role of whole-body ¹⁸fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸FDG PET/CT) in the restaging and follow-up of patients with sarcoidosis previously studied by multidetector computed tomography (MDCT).

Materials and methods

This retrospective study enroled 21 patients to evaluate the sensitivity, specificity and accuracy of ¹⁸FDG-PET/CT and MDCT. The results of the two techniques were compared with the Mc Nemar test. Cohen’s K was used to compare concordance at the different lesion sites.

Results

The sensitivity, specificity and accuracy of ¹⁸FDG-PET/CT were 80, 66.67, and 76.19 %, respectively. The sensitivity, specificity and accuracy of MDCT were 93.33, 33.33, and 76.19 %, respectively. In 16 patients who underwent whole-body MDCT, the sensitivity, specificity and accuracy values were 91.67, 81.25, and 50 % (MDCT) and 100, 50, and 87.5 % (¹⁸FDG-PET/CT).

Conclusions

¹⁸FDG-PET/CT is useful in evaluating the extent of sarcoidosis and recognising lesions at different sites, including lymph nodes, lungs, liver, spleen and bone. It also improves the interpretation of the morphological lesions seen on MDCT and depicts a larger number of lesions. Therefore, ¹⁸FDG-PET/CT could be used to complement other more traditional techniques for the restaging and follow-up in patients with sarcoidosis.     

结节病18F-FDG PET/CT的诊断及误诊原因分析

目的 对行PET/CT检查的11例结节病患者进行回顾性分析,为结节病的正确诊断提供依据.方法 对11例经手术病理检查证实(5例)和随访证实(6例)的结节病患者进行回顾性临床资料总结,根据18F-脱氧葡萄糖(FDG)PET/CT图像特征,结合病灶累及部位、分布特点、大小、标准摄取值(SUV)特点及误诊比例等进行分析总结.结果 (1)淋巴结累及者共11例:其中纵隔及双肺门淋巴结累及者11例,锁骨上窝淋巴结累及者8例,腹膜后淋巴结累及者8例,盆腔淋巴结累及者3例.(2)结外脏器累及者共7例:包括肺内结节及片状阴影4例,肝累及2例,腮腺及颞肌累及1例,双侧髂骨和骶骨累及1例.(3)病灶大小:最大直径1.0～4.6 cm之间;病灶密度:CT平扫示病变淋巴结密度30～40 HU之间,肺内病灶呈淡薄密度影;肝内病灶呈等或稍低密度影.代谢情况:所有病灶代谢均明显增高者6例;部分病灶代谢明显增高、部分轻中度增高者2例;代谢均轻中度增高者3例.(4)PET/CT正确诊断6例;误诊5例,其中误诊为恶性淋巴瘤4例、肺癌1例.结论 18FFDG PET/CT可灵敏、准确地反映结节病的全身病灶分布范围和病灶活性,但部分病例易被误诊为恶性肿瘤,尤其是恶性淋巴瘤.根据PET/CT影像特点并结合临床能提高结节病的诊断准确性.     

结节病18F-FDG PET/CT的诊断及误诊原因分析

目的 对行PET/CT检查的11例结节病患者进行回顾性分析,为结节病的正确诊断提供依据.方法 对11例经手术病理检查证实(5例)和随访证实(6例)的结节病患者进行回顾性临床资料总结,根据18F-脱氧葡萄糖(FDG)PET/CT图像特征,结合病灶累及部位、分布特点、大小、标准摄取值(SUV)特点及误诊比例等进行分析总结.结果 (1)淋巴结累及者共11例:其中纵隔及双肺门淋巴结累及者11例,锁骨上窝淋巴结累及者8例,腹膜后淋巴结累及者8例,盆腔淋巴结累及者3例.(2)结外脏器累及者共7例:包括肺内结节及片状阴影4例,肝累及2例,腮腺及颞肌累及1例,双侧髂骨和骶骨累及1例.(3)病灶大小:最大直径1.0～4.6 cm之间;病灶密度:CT平扫示病变淋巴结密度30～40 HU之间,肺内病灶呈淡薄密度影;肝内病灶呈等或稍低密度影.代谢情况:所有病灶代谢均明显增高者6例;部分病灶代谢明显增高、部分轻中度增高者2例;代谢均轻中度增高者3例.(4)PET/CT正确诊断6例;误诊5例,其中误诊为恶性淋巴瘤4例、肺癌1例.结论 18FFDG PET/CT可灵敏、准确地反映结节病的全身病灶分布范围和病灶活性,但部分病例易被误诊为恶性肿瘤,尤其是恶性淋巴瘤.根据PET/CT影像特点并结合临床能提高结节病的诊断准确性.     

结节病18F-FDG PET/CT的诊断及误诊原因分析

目的 对行PET/CT检查的11例结节病患者进行回顾性分析,为结节病的正确诊断提供依据.方法 对11例经手术病理检查证实（5例）和随访证实（6例）的结节病患者进行回顾性临床资料总结,根据18F-脱氧葡萄糖（FDG）PET/CT图像特征,结合病灶累及部位、分布特点、大小、标准摄取值（SUV）特点及误诊比例等进行分析总结.结果 （1）淋巴结累及者共11例：其中纵隔及双肺门淋巴结累及者11例,锁骨上窝淋巴结累及者8例,腹膜后淋巴结累及者8例,盆腔淋巴结累及者3例.（2）结外脏器累及者共7例：包括肺内结节及片状阴影4例,肝累及2例,腮腺及颞肌累及1例,双侧髂骨和骶骨累及1例.（3）病灶大小：最大直径1.0～4.6 cm之间 病灶密度：CT平扫示病变淋巴结密度30～40 HU之间,肺内病灶呈淡薄密度影 肝内病灶呈等或稍低密度影.代谢情况：所有病灶代谢均明显增高者6例 部分病灶代谢明显增高、部分轻中度增高者2例 代谢均轻中度增高者3例.（4）PET/CT正确诊断6例 误诊5例,其中误诊为恶性淋巴瘤4例、肺癌1例.结论 18FFDG PET/CT可灵敏、准确地反映结节病的全身病灶分布范围和病灶活性,但部分病例易被误诊为恶性肿瘤,尤其是恶性淋巴瘤.根据PET/CT影像特点并结合临床能提高结节病的诊断准确性.     

Be aware of disseminated sarcoidosis with diffuse subcutaneous nodules on F-18 FDG PET

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology that typically affects young adults. Definitive diagnosis requires compatible clinical and radiologic manifestations and histopathologic detection of noncaseating granulomas. In recent years, F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has been proposed to play a role in the diagnosis and management of sarcoidosis. Although disseminated sarcoidosis has been reported in nearly all organs including the skin, subcutaneous sarcoidosis is relatively rare with few reports using F-18 FDG PET. We report a case of disseminated sarcoidosis with diffuse subcutaneous nodules demonstrating avid F-18 FDG uptake on PET.     

A comparative study of FDG PET/CT and enhanced multi-detector CT for detecting liver metastasis according to the size and location

Purpose

The aim of this study was to compare the diagnosability between ¹⁸F-fluorodeoxyglucose (FDG) PET/CT and enhanced multi-detector CT (MDCT) for the detection of liver metastasis (LM) according to the size and location in liver and to evaluate standard maximum standardized uptake values (SUVmax) of all liver metastatic lesions.

Materials and methods

One hundred two consecutive patients with malignancy who underwent both FDG PET/CT and MDCT for LM evaluation were retrospectively reviewed. Among them, 56 patients with LM were enrolled in this study. LM was confirmed by follow-up imaging studies after at least 6 months or by histopathology. FDG PET/CT and MDCT images were visually analyzed using three-point scale by the consensus of two radiologists and two nuclear medicine physicians. The size and location (central vs. sub-capsular) of the all liver lesions were evaluated using MDCT images. Furthermore, SUVmax of all liver lesions on FDG PET/CT images were calculated.

Results

A total of 146 liver lesions were detected by FDG PET/CT and MDCT and 142 of the lesions were diagnosed as LM. The detection rates of MDCT and FDG PET/CT for LM by visual analysis were 77 and 78 %, respectively. There was no significant difference of detection rate according to the overall location and size of the lesions. However, FDG PET/CT was more sensitive than MDCT for detecting small and sub-capsular LM. The detection rate of FDG PET/CT for LM was 68 % by the cutoff SUVmax of 2.7.

Conclusions

Although the diagnosabilities of MDCT and FDG PET/CT for detecting LM were comparable, FDG PET/CT is superior to MDCT for detecting small LM located in the sub-capsular portion of liver.     

Spinal cord metastases from lung cancer: detection with F-18 FDG PET/CT

Preoperative F-18 FDG PET/CT study in this 57-year-old woman showed an FDG avid lesion in the left upper lung without evidence of lymphadenopathy or distant metastasis. She underwent a left upper lobectomy in June 2005 revealing moderately poorly differentiated adenocarcinoma (pT3N0M0) and subsequent chemotherapy completed December 2005. Nine months later, a left parietal lobe metastatic lesion was surgically resected. A true whole body FDG PET/CT study in November 2006 for restaging demonstrated new FDG avid spinal cord foci, which were highly suspicious for spinal cord metastases; these lesions were confirmed by MRI. Clinically, the patient recently developed back pain without evidence of neurologic deficits.     

Usefulness of fasting 18F-FDG PET in identification of cardiac sarcoidosis.

Cardiac PET using (18)F-FDG under fasting conditions (fasting (18)F-FDG PET) is a promising technique for identification of cardiac sarcoidosis and assessment of disease activity. The aim of this study was to investigate the usefulness of fasting (18)F-FDG PET in detecting inflammatory lesions of cardiac sarcoidosis from a pathophysiologic standpoint. METHODS: Twenty-two patients with systemic sarcoidosis were classified into 2 groups of 11 each according to the presence or absence of sarcoid heart disease. Cardiac sarcoidosis was diagnosed according to the Japanese Ministry of Health and Welfare guidelines for diagnosing cardiac sarcoidosis with the exception of scintigraphic criteria. Nuclear cardiac imaging with fasting (18)F-FDG PET, (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) SPECT, and (67)Ga scintigraphy were performed in all patients. PET and SPECT images were divided into 13 myocardial segments and the standardized uptake value (SUV) of (18)F-FDG was calculated and defect scores (DS) for (99m)Tc-MIBI uptake were assessed for each segment. The total SUV (T-SUV) and total DS (TDS) were calculated as the sum of measurements for all 13 segments, and the diagnostic accuracy of fasting (18)F-FDG PET was compared with that of the other nuclear imaging modalities. In addition, pathophysiologic relationships between inflammatory activity and myocardial damage were examined by segmental comparative study using the SUV and DS. RESULTS: In patients with cardiac sarcoidosis, fasting (18)F-FDG PET revealed a higher frequency of abnormal myocardial segments than (99m)Tc-MIBI SPECT (mean number of abnormal segments per patient: 6.6 +/- 3.0 vs. 3.0 +/- 3.2 [mean +/- SD], P < 0.05). The sensitivity of fasting (18)F-FDG PET in detecting cardiac sarcoidosis was 100%, significantly higher than that of (99m)Tc-MIBI SPECT (63.6%) or (67)Ga scintigraphy (36.3%). The accuracy of fasting (18)F-FDG PET was significantly higher than (67)Ga scintigraphy. The T-SUV demonstrated a good linear correlation with serum angiotensin-converting enzyme levels (r = 0.83, P < 0.01), and the TDS showed a significant negative correlation with the left ventricular ejection fraction (r = -0.82, P < 0.01). In abnormal myocardial segments on the nuclear scan, the SUV showed a significant negative correlation with the DS (r = -0.63, P < 0.0001). CONCLUSION: This study suggests that fasting (18)F-FDG PET can detect the early stage of cardiac sarcoidosis, in which fewer perfusion abnormalities and high inflammatory activity are noted, before advanced myocardial impairment.     

Solitary 18F-fluorodeoxyglucose avid spinous process cholangiocarcinoma metastasis proven on CT guided percutaneous needle bone biopsy.

A 65-year-old female with newly diagnosed cholangiocarcinoma was referred for a FDG PET/CT for initial staging. There was a region of moderate FDG avidity localizing to the hepatic hilum representing the primary site of malignancy. An unexpected moderately FDG avid focus was demonstrated in the spinous process of the T11 vertebra with no corresponding mass lesion seen on low dose CT and no evidence of distant metastatic disease elsewhere. A percutaneous CT guided needle bone biopsy was performed which confirmed a solitary T11 spinous process metastasis on histopathology.     

Whole-body [18F]FDG PET/MRI vs. PET/CT in the assessment of bone lesions in oncological patients: initial results

Objectives

To compare [¹⁸?F]FDG PET/MRI with PET/CT for the assessment of bone lesions in oncologic patients.

Methods

This prospective study included 67 patients with solid tumours scheduled for PET/CT with [¹⁸?F]FDG who also underwent a whole-body PET/MRI scan. The datasets (PET/CT, PET/MRI) were rated by two readers regarding lesion conspicuity (four-point scale) and diagnostic confidence (five-point scale). Median scores were compared using the Wilcoxon test.

Results

Bone metastases were present in ten patients (15 %), and benign bone lesions in 15 patients (22 %). Bone metastases were predominantly localized in the pelvis (18 lesions, 38 %) and the spine (14 lesions, 29 %). Benign bone lesions were exclusively osteosclerotic and smaller than the metastases (mean size 6 mm vs. 23 mm). While PET/CT allowed identification of 45 of 48 bone metastases (94 %), PET/MRI allowed identification of all bone metastases (100 %). Conspicuity of metastases was high for both modalities with significantly better results using PET/MRI (p?<?0.05). Diagnostic confidence in lesion detection was high for both modalities without a significant difference. In benign lesions, conspicuity and diagnostic confidence were significantly higher with PET/CT (p?<?0.05).

Conclusions

[¹⁸?F]FDG PET/MRI shows high potential for the assessment of bone metastases by offering superior lesion conspicuity when compared to PET/CT. In hypersclerotic, benign bone lesions PET/CT still sets the reference.

Key Points

? PET/MRI and PET/CT are of equal value for the identification of disease-positive patients ? PET/MRI offers higher lesion conspicuity as well as diagnostic confidence ? PET/MRI is an attractive new alternative for the assessment of bone metastases     

FDG-PET and CT patterns of bone metastases and their relationship to previously administered anti-cancer therapy

Purpose To assess ¹⁸F-fluorodeoxyglucose (FDG) uptake in bone metastases in patients with and without previous treatment, and compare positive positron emission tomography (PET) with osteolytic or osteoblastic changes on computed tomography (CT).Methods One hundred and thirty-one FDG-PET/CT studies were reviewed for bone metastases. A total of 294 lesions were found in 76 patients, 81 in untreated patients and 213 in previously treated patients. PET was assessed for abnormal FDG uptake localised by PET/CT to the skeleton. CT was evaluated for bone metastases and for blastic or lytic pattern. The relationship between the presence and pattern of bone metastases on PET and CT, and prior treatment was statistically analysed using the chi-square test.Results PET identified 174 (59%) metastases, while CT detected 280 (95%). FDG-avid metastases included 74/81 (91%) untreated and 100/213 (47%) treated lesions (p<0.001). On CT there were 76/81 (94%) untreated and 204/213 (96%) treated metastases (p NS). In untreated patients, 85% of lesions were seen on both PET and CT (26 blastic, 43 lytic). In treated patients, 53% of lesions were seen only on CT (95 blastic, 18 lytic). Of the osteoblastic metastases, 65/174 (37%) were PET positive and 98/120 (82%), PET negative (p<0.001).Conclusion The results of the present study indicate that when imaging bone metastases, prior treatment can alter the relationship between PET and CT findings. Most untreated bone metastases are PET positive and lytic on CT, while in previously treated patients most lesions are PET negative and blastic on CT. PET and CT therefore appear to be complementary in the assessment of bone metastases.