Dual-time point PET/CT with F-18 FDG for the differentiation of malignant and benign bone lesions

Non‑surgical outcomes and risk factors for pulmonary metastasis from giant cell tumor of bone

The present study detailed four factors associated with an increased risk of pulmonary metastasis, age, pathological fracture, local recurrence and mode of treatment. Local recurrence and pathological fracture were independent risk factors for developing metastasis. From January 2016 to December 2021, data from 50 patients diagnosed with giant cell tumor of bone (GCTB) treated in Khon Kaen Hospital, Thailand, were retrospectively analyzed. The risk factors, including age at diagnosis, location of GCTB, clinical presentation, Campanacci stage and no. of local recurrences, for GCTB-induced pulmonary metastasis were evaluated using univariate and multivariable logistic regression analyses. Of the 50 patients analyzed, 9 patients (18%), with a mean age of 46.3 years (range, 18-68 years), developed pulmonary metastasis. No patients died from pulmonary metastasis in the present study. Statistically significant associations were observed between the development of metastasis and both clinical fracture [odds ratio (OR), 6.107; 95% confidence interval (CI), 1.08-34.70] and local recurrence (OR, 6.48; 95% CI, 1.03-40.87). Patients presenting with both a clinical fracture and local tumor recurrence require more rigorous clinical observation due to the significantly elevated risk of disease progression.

Diagnostic Approach and Differences between Spinal Infections and Tumors

STUDY DESIGN

A systematic review of the literature about differential diagnosis between spine infection and bone tumors of the spine.

BACKGROUND AND PURPOSE

The differential diagnosis between spine infection and bone tumors of the spine can be misled by the prevalence of one of the conditions over the other in different areas of the world. A review of the existing literature on suggestive or even pathognomonic imaging aspects of both can be very useful for correctly orientating the diagnosis and deciding the most appropriate area for biopsy. The purpose of our study is to identify which imaging technique is the most reliable to suggest the diagnosis between spine infection and spine bone tumor.

METHODS

A primary search on Medline through PubMed distribution was made. We identified five main groups: tuberculous, atypical spinal tuberculosis, pyogenic spondylitis, and neoplastic (primitive and metastatic). For each group, we evaluated the commonest localization, characteristics at CT, CT perfusion, MRI, MRI with Gadolinium, MRI diffusion (DWI) and, in the end, the main features for each group.

RESULTS

A total of 602 studies were identified through the database search and a screening by titles and abstracts was performed. After applying inclusion and exclusion criteria, 34 articles were excluded and a total of 22 full-text articles were assessed for eligibility. For each article, the role of CT-scan, CT-perfusion, MRI, MRI with Gadolinium and MRI diffusion (DWI) in distinguishing the most reliable features to suggest the diagnosis of spine infection versus bone tumor/metastasis was collected.

CONCLUSION

Definitive differential diagnosis between infection and tumor requires biopsy and culture. The sensitivity and specificity of percutaneous biopsy are 72% and 94%, respectively. Imaging studies can be added to address the diagnosis, but a multidisciplinary discussion with radiologists and nuclear medicine specialists is mandatory.

18F-FDG PET–CT dual-time imaging in detection and characterization of recurrent lesions in patients with testicular cancer

Background

Testicular cancer is the second most frequent form of male genital tumors. Globally, testicular malignancy has risen over the last forty years. Among malignant testicular tumors, germ cell tumors represent approximately 95% of all tumors. They are classified into seminomatous and non-seminomatous tumors as they differ in clinical features, therapy, and prognosis. Despite the increasing value of whole-body fluorodeoxyglucose positron emotion tomography/computerized tomography (18FDG-PET/CT) for all malignancies, the practical function of this imaging method in testicular germ cell tumors is still unknown. We aim to assess the diagnostic performance of18FDG-PET/CT dual-time-point imaging (DTPI) in the detection and characterization of recurrent testicular cancer lesions.

Results

18FDG-PET/CT DTPI showed higher specificity (SP) in lesions' delectability and characterization for local, nodal, and distant lesions than the single-time-point imaging (STPI) (97.6%, 93.8%, and 97% versus 95.2%, 68.8%, and 84.8%, respectively) and higher sensitivity (SN) for nodal and distant lesions (97% and 93.8% versus 87.8% and 87.5%, respectively). The mean SUVmaxD and the RI values—not the SUVmaxE—of the malignant lesions were significantly greater than the benign lesions (p 0.001*).

Conclusions

18FDG-PET/CT DTPI and its related indices (SUVmaxD and the RI) are more accurate, sensitive, and specific than the STPI in the characterization of recurrent lesions in testicular cancer patients.

Semiquantitative analysis using whole-body dynamic F-18 fluoro-2-deoxy-glucose-positron emission tomography to differentiate between benign and malignant lesions

OBJECTIVES

To investigate whether whole-body dynamic positron emission tomography (PET) is useful for differentiating benign and malignant lesions.

METHODS

In this retrospective study, data from a cohort of 146 lesions from 187 patients who consecutively underwent whole-body dynamic PET scans at our hospital for suspected lesions in the lung, lymph nodes, liver, bone, esophagus, and colon were analyzed. Patients with malignant lymphomas, accumulations > 5 cm in length along the long axis of the esophagus, or lesions in the colon in which the site of accumulation moved during the imaging period were excluded. Patients were administered 3.7 MBq/kg of fluorine-18-fluorodeoxyglucose (F-18 FDG), and dynamic imaging was initiated 60 min after administration. We defined the 60-65, 65-70, 70-75, and 75-80 min time mark as the first, second, third, and fourth pass, respectively. The static image is the summed average of all the four pass images. We measured the accumulation in the mean image of the whole-body dynamic PET scan, which was arithmetically similar to the maximum standardized uptake value (SUVmax) throughout the whole-body static images obtained during 20 min of imaging (S-SUVmax). The ratio of SUVmax in the dynamic first pass(60-65 min after FDG administration) and fourth pass(75-80 min after FDG administration) was calculated as R-SUVmax.

RESULTS

The S-SUVmax in the lung, lymph nodes, and bone did not differ significantly between the benign and malignant groups. However, there was a significant difference in R-SUVmax, which was > 1 in most malignant lesions indicating an increase in accumulation during routine scan time. Significant differences were observed between benign and malignant lesions of the liver in both S-SUVmax and R-SUVmax values, with the latter being > 1 in most malignant lesions.

CONCLUSIONS

Whole-body dynamic PET for 20 min starting 1 h after FDG administration improved the accuracy of malignant lesion detection in the liver, lymph nodes, lung, and bone. The incremental improvement was small, and the FDG dynamics in the distribution of values between benign and malignant overlapped. Additional information from whole-body dynamic imaging can help detect malignant lesions in these sites without increasing patient burden or prolonging imaging time.

Diagnostic value of 18F-FDG PET/CT in discriminating between benign and malignant lesions of the ribs

PURPOSE

Imaging biomarkers for rib mass are needed to optimize treatment plan. We investigated the diagnostic value of metabolic and volumetric parameters from 18F-fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) in discriminating between benign and malignant lesions of the ribs.

PATIENTS AND METHODS

Fifty-seven patients with pathologically proven diagnosis of rib lesions were retrospectively enrolled. The size of rib lesions, the maximum, mean, and peak standardized uptake value (SUVmax, SUVmean, SUVpeak), tumor-to-background ratio (TBR), metabolic tumor volume (MTV), and total lesions glycolysis (TLG) were measured. The FDG uptake patterns (segmental and discrete) and CT findings (soft tissue involvement and fracture) were also reviewed.

RESULTS

Among the multiple parameters extracted from PET/CT, the MTV of malignant lesions was significantly higher than that of benign lesions (median; 4.7 vs 0.2, respectively, P = .041). In receiver operating characteristics curve analysis, MTV had the largest area under curve of 0.672 for differentiating malignant from benign lesions. For identifying malignant lesions, an MTV threshold of 0.5 had a sensitivity of 85.0%, specificity of 47.1%, positive predictive value of 79.1%, negative predictive value of 57.1%, and accuracy of 73.7%. The presence of adjacent soft tissue involvement around rib lesions showed a significant association with malignancy (odds ratio = 6.750; 95% CI, 1.837-24.802, P = .003).

CONCLUSIONS

The MTV is a useful PET/CT parameter for assisting in the differential diagnosis of suspected malignant lesions of the ribs. CT finding of adjacent soft tissue involvement around rib was significantly associated with malignant lesions of the ribs.

Dynamic whole-body FDG-PET imaging for oncology studies

Introduction

Recent PET/CT systems have improved sensitivity and spatial resolution by smaller PET detectors and improved reconstruction software. In addition, continuous-bed-motion mode is now available in some PET systems for whole-body PET imaging. In this review, we describe the advantages of dynamic whole-body FDG-PET in oncology studies.

Methods

PET–CT imaging was obtained at 60 min after FDG administration. Dynamic whole-body imaging with continuous bed motion in 3 min each with flow motion was obtained over 400 oncology cases. For routine image analysis, these dynamic phases (usually four phases) were summed as early FDG imaging. The image quality of each serial dynamic imaging was visually evaluated. In addition, changes in FDG uptake were analyzed in consecutive dynamic imaging and also in early delayed (90 min after FDG administration) time point imaging (dual-time-point imaging; DTPI). Image interpretation was performed by consensus of two nuclear medicine physicians.

Result

All consecutive dynamic whole-body PET images of 3 min duration had acceptable image quality. Many of the areas with physiologically high FDG uptake had altered uptake on serial images. On the other hand, most of the benign and malignant lesions did not show visual changes on serial images. In the study of 60 patients with suspected colorectal cancer, unchanged uptake was noted in almost all regions with pathologically proved FDG uptake, indicating high sensitivity with high negative predictive value on both serial dynamic imaging and on DTPI. We proposed another application of serial dynamic imaging for minimizing motion artifacts for patients who may be likely to move during PET studies.

Discussion

Dynamic whole-body imaging has several advantages over the static imaging. Serial assessment of changes in FDG uptake over a short period of time is useful for distinguishing pathological from physiological uptake, especially in the abdominal regions. These dynamic PET studies may minimize the need for DPTI. In addition, continuous dynamic imaging has the potential to reduce motion artifacts in patients who are likely to move during PET imaging. Furthermore, kinetic analysis of the FDG distribution in tumor areas has a potential for precise tissue characterization.

Conclusion

Dynamic whole-body FDG-PET imaging permits assessment of serial FDG uptake change which is particularly useful for differentiation of pathological uptake from physiological uptake with high diagnostic accuracy. This imaging can be applied for minimizing motion artifacts. Wide clinical applications of such serial, dynamic whole-body PET imaging is expected in oncological studies in the near future.

Diagnostic performance of PET/CT in primary malignant bone tumors

Background

Nowadays, PET/CT plays a substantial role in the diagnosis of different types of tumor by its ability to provide combined functional and anatomic imaging in the same session. The purpose of this study is to evaluate the added value of PET/CT in staging and re-staging of primary malignant bone tumors.

Results

Out of the studied 40 patients, 7 patients were referred for primary staging of different types of histologically proven primary malignant bone tumors, their FDG-PET/CT studies yielded additional diagnostic information in 28.6% of them. Thirty three patients were referred either for assessment of treatment response or for follow-up to detect any viable lesions; FDG-PET/CT was more sensitive and specific than CT in follow-up and assessment of treatment response with PET/CT sensitivity 94.4%, specificity 86.7%, and total accuracy 90.9% and CT sensitivity 88.2%, specificity 81.2%, and total accuracy 84.8%.

Conclusions

PET/CT was an accurate imaging modality in evaluation of primary malignant bone tumors regarding tumor staging, assessment of therapeutic response and detection of metastatic disease as compared to CT.

18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Findings of Osteoblastoma Of Rib - A Rare Benign Tumor with Unusual Site and Uncommon Age

Osteoblastoma accounts for approximately 1% of all primary bone tumors. We report F18-fluorodeoxyglucose positron emission tomography/computed tomography (F18-FDG PET/CT) findings of an osteoblastoma in the rib of a 20-month-old girl child, who had fever with pain in the right shoulder for 4 months. This lesion was initially judged as a malignant bone tumor but a biopsy revealed it to be an osteoblastoma. The age of patient and predominant site of disease involvement contributes to uniqueness of our case. In our case, F18-FDG PET/CT has facilitated biopsy planning and ruled out other sites of disease involvement.

Relationship between Standard Uptake Values of Positron Emission Tomography/Computed Tomography and Salivary Metabolites in Oral Cancer: A Pilot Study

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) is usually used for staging or evaluation of treatment response rather than for cancer screening. However, ¹⁸F-FDG PET/CT has also been used in Japan for cancer screening in people with no cancer symptoms, and accumulating evidence supports this application of ¹⁸F-FDG PET/CT. Previously, we have observed a correlation between the saliva and tumor metabolomic profiles in patients with oral cancer. Hence, if salivary metabolites demonstrate a significant correlation with PET parameters such as the maximum standardized uptake value (SUV_max), they may have the potential to be used as a screening tool before PET/CT to identify patients with high SUV_max. Hence, in this study, we aimed to explore the relationship between salivary metabolites and SUV_max of ¹⁸F-FDG PET/CT using previously collected data. ¹⁸F-FDG PET/CT was performed for staging 26 patients with oral cancer. The collected data were integrated and analyzed along with quantified salivary hydrophilic metabolites obtained from the same patients with oral cancer and controls (n = 44). In total, 11 metabolites showed significant correlations with SUV_max in the delayed phases. A multiple logistic regression model of the two metabolites showed the ability to discriminate between patients with oral cancer and controls, with an area under the receiver operating characteristic curve of 0.738 (p = 0.001). This study uniquely confirmed a relationship between salivary metabolites and SUV_max of PET/CT in patients with oral cancer; salivary metabolites were significantly correlated with SUV_max. These salivary metabolites can be used as a screening tool before PET/CT to identify patients with high SUV_max, i.e., to detect the presence of oral cancer.

Two cases of osteoblastic bone metastasis from muscle-invasive bladder cancer with discrepancy in response to chemotherapy: problems and limitations of bone biopsy

We report two cases of muscle-invasive bladder cancer (MIBC) with increasing multiple osteoblastic bone lesions but shrinking other lesions in response to chemotherapy. Case 1 had MIBC and received radical cystectomy followed by adjuvant gemcitabine plus cisplatin chemotherapy (GC). Three years after, follow computed tomography (CT) showed development of multiple lymph node metastasis, and then we performed GC as a first-line systemic chemotherapy. After two cycles of GC, CT showed de novo multiple osteoblastic lesions although metastatic lymph nodes were shrunk. Biopsy of the sternum revealed metastatic urothelial carcinoma. Case 2 had MIBC with multiple osteoblastic lesions on CT and bone scintigraphy, which was initially diagnosed as cT3bN0M1. After one cycle of GC, the number of osteoblastic lesions obviously increased although bladder tumor was regressed. Since the clinical course was unusual, biopsy of the clavicle was done. The histological diagnosis was benign osteoblastic bone disease, then the clinical diagnosis was revised to non-metastatic MIBC, and radical cystectomy was performed. Ten months after surgery, the patients complained worsening backache and CT showed increase in number of osteoblastic lesions. Eventually, ilium biopsy revealed bone metastasis of urothelial carcinoma. In case of atypical finding and unusual clinical course, biopsy of suspected metastatic lesion may be informative although adequate sampling should be secured.

Imaging Analyses of Bone Tumors

Despite the evolution in imaging, especially the introduction of advanced imaging technologies, radiographs still are the key for the initial assessment of a bone tumor. Important aspects to be considered in radiographs are the location, shape and size or volume, margins, periosteal reaction, and internal mineralization of the tumor's matrix; careful evaluation of these may provide for accurate diagnosis in >80% of cases. Computed tomography and magnetic resonance imaging are often diagnostic for lesions with typical findings such as the nidus of osteoid osteoma and bone destruction such as in Ewing sarcoma and lymphoma that may be difficult to detect with radiographs; they may also be used for surgical planning. Magnetic resonance imaging accurately determines the intraosseous extent and articular and vascular involvement by the tumor. This article summarizes the diagnostic accuracy of imaging analyses in bone tumors and emphasizes the specific radiographic findings for optimal radiographic diagnosis of the patients with these tumors.

Assessing PET Parameters in Oncologic 18F-FDG Studies

PET imaging, particularly oncologic applications of ¹⁸F-FDG, has become a routine diagnostic study. To better describe malignancies, various PET parameters are used. In ¹⁸F-FDG PET studies, SUV_max is the most commonly used parameter to measure the metabolic activity of the tumor. In obese patients, SUV corrected by lean body mass (SUL), and in pediatric patients, SUV corrected by body surface area, are recommended. Metabolic tumor volume is an important parameter to determine the local and total tumor burden. Total lesion glycolysis (SUV_mean × metabolic tumor volume) provides information about averages. Some treatment response assessment protocols recommend using the SUV_peak or SUL_peak of the tumor. Tumor-to-liver ratio and tumor-to-blood-pool ratio are helpful when comparing studies for treatment response assessment. Dual-time-point PET imaging with retention index can help differentiate malignant from benign lesions and may help detect small lesions. Dynamic ¹⁸F-FDG PET imaging and quantitative analysis can measure the metabolic, phosphorylation, and dephosphorylation rates of lesions but are mainly used for research purposes. In this article, we will review the currently available PET parameters in ¹⁸F-FDG studies with their importance, uses, limitations, and reasons for erroneous results.

Dynamics of fluorine-18-fluorodeoxyglucose uptake in the liver and its correlation with hepatic fat content and BMI

PURPOSE

The aim of this study was to explore the rate of elimination of fluorine-18-fluorodeoxyglucose (F-FDG) from the liver and assess the impact of hepatic fat and obesity on F-FDG clearance in early and delayed PET scans. We hypothesized that an increase in liver fat may cause a decline in hepatic F-FDG elimination with potential consequences as measured by dual time-point F-FDG PET/CT imaging.

PATIENTS AND METHODS

A total of 32 patients from the Cardiovascular Molecular Calcification Assessed by F-NaF PET/CT (CAMONA) clinical trial (17 males, 15 females; mean age: 47.2 years, range: 23-69 years, mean BMI: 27.2 kg/m) were enrolled and underwent F-FDG PET/CT 90 and 180 min after tracer injection. Global mean standardized uptake value (SUVmean) (i.e. the average of SUVmean in segmented liver slices) and average maximum standardized uptake value (SUVmax) (i.e. the average of the SUVmax values recorded in same slices) were calculated for semiquantification of liver F-FDG uptake at both time-points. Percentage difference in global SUVmean and average SUVmax were also calculated to yield respective retention indices (RImean and RImax). Changes in global SUVmean, average SUVmax, RImean, and RImax from 90 to 180 min were correlated with BMI and liver fat content as measured by CT Hounsfield units.

RESULTS

There was a 12.2±3.5 percent reduction in global liver SUVmean and a 4.1±5.8 percent reduction in average SUVmax at 180 min scan as compared with the 90 min time-point. RImean and RImax were inversely correlated with liver fat content and positively correlated with BMI.

CONCLUSION

We observed a time-dependent decrease in global hepatic SUVmean and average SUVmax, which was affected by the amount of liver fat. Patients with higher BMI and hepatic fat content tended to retain F-FDG.

Significance of incidental intra-articular and peri-articular FDG avid foci on PET/CT

BACKGROUND

Positron emission tomography/computed tomography (PET/CT) is a useful imaging adjunct in patients with sarcoma. Intra-articular and peri-articular 18F-fluoro-2-deoxy-D-glucose (FDG) avid lesions are often discovered incidentally.

PURPOSE

To describe the etiology, appearance, and standardized uptake values (SUV) of incidentally detected FDG avid intra-articular and peri-articular foci in patients with sarcoma.

MATERIAL AND METHODS

The institutional sarcoma database between November 2011 and November 2016 was retrospectively reviewed. Patients were included if a PET/CT scan was performed and an FDG avid intra-articular or peri-articular focus was found that was distinct from the primary sarcoma.

RESULTS

The majority of FDG avid foci represented benign, non-physiologic conditions such as osteoarthritis, enthesopathy, bursitis, and post-surgical changes. Six patients each had radiographic features consistent with tenosynovial giant cell tumor (TSGCT) and metastatic disease, respectively. Lower SUV, bilateral findings, and the absence of metastatic disease elsewhere were associated with benign etiologies. There was a statistically significant difference between the mean SUV measured in patients with TSGCT and those with benign, non-physiologic conditions ( P < 0.001). The difference between the benign, non-physiologic cohort and the cohort with widespread metastatic disease did not reach statistical significance ( P = 0.07).

CONCLUSIONS

In patients with soft-tissue or osseous sarcomas, isolated FDG avid intra-articular or peri-articular foci without additional metastatic lesions likely represent benign processes. Isolated intra-articular or peri-articular foci with significantly elevated SUV measurements were favored to represent TSGCT in this series.

Diagnostic Accuracy of Dual-Time-Point Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography in Verification Local Recurrence in Pancreatic Cancer Patients

Purpose:

The aim of this study was to evaluate the accuracy of dual-time point in differentiating benign from malignant local recurrent lesions in pancreatic cancer.

Patients and Methods:

Thirty-four patients with pancreatic cancer (22 males and 12 females, mean age: 58.3 ± 10.3) who presented with soft-tissue lesions at the operative bed. Early whole-body positron emission tomography/computed tomography (PET/CT) and delayed imaging on the abdomen were performed. The maximum standardized uptake value (SUVmax) of the initial image (SUVmax E) and the delayed image (SUVmax D) were determined. A Retention Index (RI) was also calculated. These indices were correlated with histopathology and follow-up as reference criteria.

Results:

No significant statistical difference in SUVmaxE was found between benign and malignant lesions, while SUVmaxD and RI of the malignant lesions (mean 8.6 ± 2.7 and 35.8 ± 18.3, respectively) were significantly higher than those of benign ones (mean 3.3 ± 1.4 and-6.2 ± 15.2, respectively) (P < 0.005). With SUVmaxD 4.9, malignancy could be predicted with the highest sensitivity (95.8%) and accuracy (94.1%) between the whole parameters. The estimated negative and positive predictive values (PPVs) were 90.0% and 95.8%, respectively. A cutoff point 16 for RI showed higher specificity and PPV (100% and 100%, respectively). Forty-seven total (11 benign and 36 malignant) lesions were identified. Increased SUVmax is noted on delayed images in most of malignant lesions, except for two that maintained stationary.

Conclusion:

Dual-time-point 18F fluorodeoxyglucose-PET/CT seems to be a reliable additional method to differentiate between malignant and benign postoperative local soft-tissue lesions in patients with pancreatic cancer.

Management of Primary Osseous Spinal Tumors with PET

Knowledge of the PET imaging findings of osseous spinal neoplasms is essential, because they are common incidental findings on PET scans done for staging of unrelated primary malignancies. Additionally, PET can help differentiate lesions that are not clearly defined by anatomic modalities alone. PET can also be used for follow-up of aggressive tumors to assess response to treatment, often proving superior to CT or MR imaging alone for this purpose. This review discusses the role of PET/CT and PET/MR imaging in the diagnosis and management of primary benign and malignant osseous tumors of the spine.

Applications of PET/CT and PET/MR Imaging in Primary Bone Malignancies

Primary bone malignancies are characterized with anatomic imaging. However, in recent years, there has been an increased interest in PET/computed tomography scanning and PET/MRI with fludeoxyglucose F 18 for evaluating and staging musculoskeletal neoplasms. These hybrid imaging modalities have shown promise largely owing to their high sensitivity, ability to perform more thorough staging, and ability to monitor treatment response. This article reviews the current role of PET/computed tomography scanning and PET/MRI in primary malignancies of bone, with an emphasis on imaging characteristics, clinical usefulness, and current limitations.

Quantification of FDG-PET/CT with delayed imaging in patients with newly diagnosed recurrent breast cancer

Background

Several studies have shown the advantage of delayed-time-point imaging with 18F-FDG-PET/CT to distinguish malignant from benign uptake. This may be relevant in cancer diseases with low metabolism, such as breast cancer. We aimed at examining the change in SUV from 1 h (1h) to 3 h (3h) time-point imaging in local and distant lesions in patients with recurrent breast cancer. Furthermore, we investigated the effect of partial volume correction in the different types of metastases, using semi-automatic quantitative software (ROVER™).

Methods

One-hundred and two patients with suspected breast cancer recurrence underwent whole-body PET/CT scans 1h and 3h after FDG injection. Semi-quantitative standardised uptake values (SUVmax, SUVmean) and partial volume corrected SUVmean (cSUVmean), were estimated in malignant lesions, and as reference in healthy liver tissue. The change in quantitative measures from 1h to 3h was calculated, and SUVmean was compared to cSUVmean. Metastases were verified by biopsy.

Results

Of the 102 included patients, 41 had verified recurrent disease with in median 15 lesions (range 1-70) amounting to a total of 337 malignant lesions included in the analysis. SUVmax of malignant lesions increased from 6.4 ± 3.4 [0.9-19.7] (mean ± SD, min and max) at 1h to 8.1 ± 4.4 [0.7-29.7] at 3h. SUVmax in breast, lung, lymph node and bone lesions increased significantly (p < 0.0001) between 1h and 3h by on average 25, 40, 33, and 27%, respectively. A similar pattern was observed with (uncorrected) SUVmean. Partial volume correction increased SUVmean significantly, by 63 and 71% at 1h and 3h imaging, respectively. The highest impact was in breast lesions at 3h, where cSUVmean increased by 87% compared to SUVmean.

Conclusion

SUVs increased from 1h to 3h in malignant lesions, SUVs of distant recurrence were in general about twice as high as those of local recurrence. Partial volume correction caused significant increases in these values. However, it is questionable, if these relatively modest quantitative advances of 3h imaging are sufficient to warrant delayed imaging in this patient group.

Trial registration

ClinicalTrails.gov NCT01552655. Registered 28 February 2012, partly retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12880-018-0254-8) contains supplementary material, which is available to authorized users.

[Differentiation between Hepatic Focal Lesions and Heterogenous Physiological Accumulations by Early Delayed Scanning in 18F-FDG PET/CT Examination]

PURPOSE

We examined whether early delayed scanning is useful for differentiation of liver lesion and heterogenous physiological accumulation in positron emission tomography (PET) examination.

METHODS

The subjects of the study were 33 patients with colorectal cancer who underwent PET examination and were added early delayed scanning to distinguish between liver lesions and heterogenous physiological accumulation to conventional early images. We placed same regions of interest (ROI) in the tumor and hepatic parenchyma for early delayed and conventional early images. Then, we measured SUVmax of the ROIs and calculated tumor to liver parenchyma uptake ratio (TLR). In addition, change rates between early and early delayed images were calculated for the SUVmax and TLR.

RESULTS

The receiver operating characterstic (ROC) analysis result of SUVmax showed the highest SUVmax change rate, and the ROC analysis result of TLR showed the highest early delayed scanning. The SUVmax of the lesions did not change between early scan and early delayed scanning (p=0.98), but it decreased significantly in the normal group (p<0.001). TLR of the lesion group was significantly increased (p<0.001) in early delayed images compared to early scan and TLR significantly decreased in the normal group (p<0.001). The AUC of the ROC curve showed the highest SUVmax change rate (0.99).

CONCLUSION

Early delayed scanning could distinguish between liver lesions and heterogenous physiological accumulation in colon cancer patients.

Non-oncologic Applications of PET/CT and PET/MR in Musculoskeletal, Orthopedic, and Rheumatologic Imaging: General Considerations, Techniques, and Radiopharmaceuticals

Positron Emission Tomography (PET) is often underutilized in the field of musculoskeletal imaging, with key reasons including the excellent performance of conventional musculoskeletal MRI, the limited spatial resolution of PET, and the lack of reimbursement for PET for non-oncologic musculoskeletal indications. However, with improvements in PET/CT and PET/MR imaging over the last decade as well as an increased understanding of the pathophysiology of musculoskeletal diseases, there is an emerging potential for PET as a primary or complementary modality in the management of rheumatologic and orthopedic patients. Specific advantages of PET include the convenience of whole body imaging in a single session, the relative resilience of the modality in the imaging of metallic implants compared to CT and MRI, the ability to evaluate deep joints not amenable to palpation, and the potential for improved specificity of diagnosis with novel radiopharmaceuticals. In this review, we discuss multiple radiopharmaceuticals and technical consideration of PET/CT and PET/MRI that can be employed in imaging of non-tumoral bone and soft tissue disorders. Both PET/CT and PET/MR hold significant promise in the field of musculoskeletal imaging, and with further radiopharmaceutical development and clinical research, these hybrid modalities can potentially transform the current management of patients with orthopedic and rheumatologic disease.

Dual time-point 18F-FDG PET/CT imaging with multiple metabolic parameters in the differential diagnosis of malignancy-suspected bone/joint lesions

The purpose of this study was to evaluate the diagnostic potential of dual time-point¹⁸F-FDG PET/CT imaging with multiple metabolic parameters in malignancy-suspected bone/joint lesions. Fifty seven consecutive patients were recruited. PET parameters including SUVmax, SUVmean, metabolic tumor volume (MTV), total lesional glycolysis (TLG) and retention indexes (RIs) were obtained. Thirty five malignant and 22 benign lesions were confirmed by pathology. In all, 48 receiver operating characteristic (ROC) curves were derived. For SUVmax, MTV2.0, TLG2.0, MTV2.5 and TLG2.5, areas under the curves (AUCs) of early time-point imaging were similar to those of delayed time (P > 0.05), while higher than those of dual time (P< 0.05). For MTV50%max, TLG50%max, MTV75%max and TLG75%max, AUCs of early time-point imaging were lower than those of delayed time (P< 0.05), while similar to those of dual time (P> 0.05). In conclusion, dual time-point¹⁸F-FDG PET/CT imaging shows limited value in the differential diagnosis of malignancy-suspected bone/joint lesions. However, MTV and TLG at a fixed SUV threshold (50% or 75% of SUVmax) in delayed time-point imaging may provide better diagnostic accuracy

F-18 FDG PET differentiation of benign from malignant chondroid neoplasms: a systematic review of the literature

INTRODUCTION

Discriminating among benign chondroid tumors, low-grade chondrosarcomas, and grade 2/3 chondrosarcomas is frequently difficult with standard imaging modalities. We systematically reviewed the literature to determine the performance of PET-CT in making this distinction.

METHODS

A systematic review was performed identifying 811 PubMed- and Embase-indexed articles containing combinations of "chondrosarcoma," "enchondroma," "chondroid," "cartilage" and "PET/CT," "PET," "positron." Eight articles including 166 lesions were included. Age, gender, tumor size, histologic grade, and SUVmax values were extracted for individual lesions when possible and otherwise recorded as aggregated data. Comparisons in SUVmax among benign, low-grade, and intermediate-/high-grade chondroid neoplasms were made.

RESULTS

Individual SUVs were available for 101 lesions; 65 additional lesions were reported as aggregated data. There were 101 malignant and 65 benign tumors. Benign tumors were seen more frequently in females (p = 0.04, Fischer's exact test), but malignancy was not associated with age or lesion size. SUVmax was lower for benign (1.6 ± 0.7) than malignant tumors (4.4 ± 2.5) (p < 0.0001, t-test). SUVmax was lower for grade 0/1 (2.0 ± 0.7) than grade 2/3 (6.0 ± 3.2) (p < 0.0001, t-test). Increasing SUVmax correlated with higher grade chondroid tumors (Spearman's rank, ρ = 0.78). SUVmax ≥4.4 was 99% specific for grade 2/3 chondrosarcoma.

CONCLUSIONS

SUVmax correlates with histologic grade in intraosseous chondroid neoplasms; very low SUVmax supports a diagnosis of benign tumor, while elevated SUVmax is suggestive of higher grade chondrosarcoma.

Detailed analysis of a superficial CD34-positive fibroblastic tumor: A case report and review of the literature

Superficial cluster of differentiation (CD)34-positive fibroblastic tumor (SCPFT) is a rare mesenchymal neoplasm of borderline malignancy. It is characterized by a superficial location, marked cellular pleomorphism, an extremely low incidence of mitotic figures, and strong CD34 immunohistochemical positivity. As SCPFT is a recently described neoplasm, its characteristics are yet to be fully elucidated. To the best of our knowledge, no detailed studies regarding the imaging findings and cytogenetic analyses of SCPFTs exist. The present study describes a typical case of an 18-year-old man who developed an SCPFT measuring 87×70×80 mm in the subcutaneous adipose tissue of his right thigh. Computed tomography (CT) revealed a well-marginated tumor without calcification, and the enhancement on CT was weak. The tumor demonstrated abnormal uptake on 2-(18F) fluoro-2-deoxy-D-glucose positron emission tomography (PET), with a maximum standardized uptake value of 2.57. Magnetic resonance imaging (MRI) revealed a clearly defined tumor that exhibited homogeneous low signal intensity on T1-weighted imaging and high signal intensity on T2-weighted imaging, with small lobulated structures. Histopathologically, the tumor was composed of irregular spindle-to-oval-shaped cells with eosinophilic glassy cytoplasm and hyperchromatic, bizarre and pleomorphic nuclei that frequently exhibited intranuclear pseudoinclusions. Immunohistochemically, the tumor cells were diffusely and strongly positive for CD34. The Mindbomb E3 ubiquitin protein ligase 1 labeling index was 8.6%. Ultrastructurally, the tumor cells exhibited irregular or convoluted nuclei with abundant euchromatin-prominent nucleoli. The cytoplasmic organelles consisted of scattered, abundant rough endoplasmic reticulum, mitochondria, lysosomes, ribosomal rosettes and aggregated lipid globules. Of 18 metaphase cells identified, 2 demonstrated translocation between chromosomes 2 and 5 in cytogenetic studies. To the best of our knowledge, this is the first study describing imaging data (CT, MRI and PET-CT) and chromosomal aberrations for SCPFT.

Diagnosing giant cell tumor of the bone using positron emission tomography/computed tomography: A retrospective study of 20 patients from a single center

The aim of the present study was to evaluate the sensitivity of positron emission tomography/computed tomography (PET/CT) in the diagnosis of giant cell tumor of the bone (GCTB) using the maximum standard uptake value (SUVmax), which indicates the metabolic rate of tissue. Patients diagnosed with pathologically confirmed GCTB between January 2006 and July 2015 were included in the study. Data from PET/CT scans and pathological and clinical reports for all patients were retrospectively reviewed. The SUVmax value from the PET/CT scan of each patient was retrieved and analyzed. A total of 20 patients [12 male and 8 female; age range, 12–45 years; mean age ± standard deviation (SD), 33.5±15.7] with complete PET/CT data and a pathologically and clinically confirmed diagnosis were examined. The SUVmax of GCTB was between 1.8 and 18.6, with a mean ± SD of 9.2±3.8. Although GCTB is not considered to be a malignant lesion, PET/CT scans of the tumors reveal high-grade malignant osseous sarcomas. It is, therefore, important not to mistake such lesions for osteosarcomas or metastatic malignancies of the bone.

Dual-time point 18F-FDG-PET and PET/CT for Differentiating Benign From Malignant Musculoskeletal Lesions: Opportunities and Limitations

In this review, we summarize the false-positive and false-negative results of standard ¹⁸F-FDG-PET/CT in characterizing musculoskeletal lesions and discussed the added value and limitations of dual-time point imaging (DTPI) and delayed imaging in differentiating malignant from benign musculoskeletal lesions, based on review of the peer-reviewed literature. The quantitative and semiquantitative parameters adopted for DTPI are standardized uptake value (mainly maximum standardized uptake value [SUVmax]) and retention index (RI), calculated as RI (%) = 100% × (SUV [maxD-Delayed] - SUV [maxE-Early])/SUV [maxE-Early], although the criteria and cutoff for diagnosing malignancy in studies have varied considerably. Also, there has been considerable heterogeneity in protocol (time point of delayed imaging), interpretation, and results in dual-time point (DTP) ¹⁸F-FDG-PET for differentiating malignant from benign musculoskeletal lesions in various research studies. The specificity of DTPI is a function of many factors such as the nature of the musculoskeletal lesion or malignancy in question, the prevalence of false-positive etiologies in the patient population, and the cutoff values (either SUVmax or RI) employed to define a malignancy. Despite the apparent conflicting reports on the performance, there have been certain common points of agreement regarding DTPI: (1) DTP PET increases the sensitivity of ¹⁸F-FDG-PET/CT due to continued clearance of background activity and increasing ¹⁸F-FDG accumulation in malignant lesions, when the same diagnostic criteria (as in the initial standard single-time point imaging) are used. Increased sensitivity for lesion detection can be viewed as a strong point of DTP and delayed-time point imaging. (2) The causes for false positives (such as active infectious or inflammatory lesions and locally aggressive benign tumors) and false negatives (eg, low-grade sarcomas) are the major hurdles accounting for reduced diagnostic value of the technique, with overlap of ¹⁸F-FDG uptake patterns between benign and malignant musculoskeletal lesions on DTPI. (3) DTPI, however, could still be potentially useful in increasing the confidence of interpretation such as differentiating malignancy from sites of inactive or chronic inflammation, post-treatment viable residue vs necrosis, and certain other benign lesions. (4) Consideration of diagnostic CT component of PET/CT and the patient's clinical picture can lead to increase in specificity of interpretation in a given case scenario. Further systematic research, adoption of uniform protocol, and interpretation criterion could evolve the specific indications and interpretation criteria of DTPI for improved diagnostic accuracy in musculoskeletal lesions and its clinical applications.

Musculoskeletal Imaging Findings of Hematologic Malignancies

Hematologic malignancies comprise a set of prevalent yet clinically diverse diseases that can affect every organ system. Because blood components originate in bone marrow, it is no surprise that bone marrow is a common location for both primary and metastatic hematologic neoplasms. Findings of hematologic malignancy can be seen with most imaging modalities including radiography, computed tomography (CT), technetium 99m (^99mTc) methylene diphosphonate (MDP) bone scanning, fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT, and magnetic resonance (MR) imaging. Because of the diversity of imaging appearances and clinical behavior of this spectrum of disease, diagnosis can be challenging, and profound understanding of the underlying pathophysiologic changes and current treatment modalities can be daunting. The appearance of normal bone marrow at MR imaging and FDG PET/CT is also varied due to dynamic compositional changes with normal aging and in response to hematologic demand or treatment, which can lead to false-positive interpretation of imaging studies. In this article, the authors review the normal maturation and imaging appearance of bone marrow. Focusing on lymphoma, leukemia, and multiple myeloma, they present the spectrum of imaging findings of hematologic malignancy affecting the musculoskeletal system and the current imaging tools available to the radiologist. They discuss the imaging findings of posttreatment bone marrow and review commonly used staging systems and consensus recommendations for appropriate imaging for staging, management, and assessment of clinical remission. ^©RSNA, 2017.

INCIDENTAL PAGET'S DISEASE DISGUISED AS BONE METASTASIS IN A PATIENT WITH ENDOMETRIUM CARCINOMA

Paget's disease is a disorder of aging bone which occurs in the setting of accelarated bone remodelling. In the presented case we discuss the difficulties in the diagnosis of Paget's disease in a 77 year old patient with coexisting endometrium carcinoma. The patient was initially diagnosed with metastatic bone disease due to endometrium adenocarcinoma when she was admitted to oncology clinic with pelvic pain. Bone scintigraphy with Tc99 and (18)F fluorodeoxyglucose positron emission tomography/CT revealed an increased uptake on the bone lesions which were reported as metastatic bone involvement. Although the (18)F-FDG uptake was much higher than the levels that would generally be anticipated in a case with Paget's disease, high levels of bone turnover markers indicated further evaluation in the differential diagnosis and the definitive diagnosis of Paget's disease was established with the pathological evaluation of bone biopsy.

Cavernous Hemangioma of the Rib: A Case Report

Hemangioma of the rib is a rare benign vascular tumor. Herein, we report a 63-year-old man presenting with hemangioma of the left sixth rib. An osteolytic eccentric expansive mass with calcification and focal cortical disruption was detected on chest computed tomography (CT). The mass showed low 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) avidity on positron emission tomography. The patient underwent resection of the left sixth rib. Based on the histopathology findings, a diagnosis of cavernous hemangioma was made. Rib hemangiomas and malignant lesions appear similar on CT scans; therefore, most cases of rib hemangiomas reported in the literature were treated with rib resection. However, rib hemangiomas should be included in the differential diagnosis of an asymptomatic patient if an osteolytic expansive lesion containing sunburst calcifications with low 18F-FDG avidity is observed on a CT scan.

Prognostic value of the standardized uptake value maximum change calculated by dual-time-point (18)F-fluorodeoxyglucose positron emission tomography imaging in patients with advanced non-small-cell lung cancer

Purpose

The purpose of this study was to investigate the prognostic value of the standardized uptake value maximum (SUVmax) change calculated by dual-time-point ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) imaging in patients with advanced non-small-cell lung cancer (NSCLC).

Patients and methods

We conducted a retrospective review of 115 patients with advanced NSCLC who underwent pretreatment dual-time-point ¹⁸F-fluorodeoxyglucose PET acquired at 1 and 2 hours after injection. The SUVmax from early images (SUVmax1) and SUVmax from delayed images (SUVmax2) were recorded and used to calculate the SUVmax changes, including the SUVmax increment (ΔSUVmax) and percent change of the SUVmax (%ΔSUVmax). Progression-free survival (PFS) and overall survival (OS) were determined by the Kaplan–Meier method and were compared with the studied PET parameters, and the clinicopathological prognostic factors in univariate analyses and multivariate analyses were constructed using Cox proportional hazards regression.

Results

One hundred and fifteen consecutive patients were reviewed, and the median follow-up time was 12.5 months. The estimated median PFS and OS were 3.8 and 9.6 months, respectively. In univariate analysis, SUVmax1, SUVmax2, ΔSUVmax, %ΔSUVmax, clinical stage, and Eastern Cooperative Oncology Group (ECOG) scores were significant prognostic factors for PFS. Similar results were significantly correlated with OS, except %ΔSUVmax. In multivariate analysis, ΔSUVmax and %ΔSUVmax were significant factors for PFS. On the other hand, ECOG scores were only identified as independent predictors of OS.

Conclusion

Our results demonstrated the prognostic value of the SUVmax change in predicting the PFS of patients with advanced NSCLC. However, SUVmax change could not predict OS.

Malignancy rate of biopsied suspicious bone lesions identified on FDG PET/CT

PURPOSE

To determine the malignancy rate of bone lesions identified on FDG PET/CT in patients who have undergone CT-guided biopsy because of the suspicion of malignancy.

METHODS

This single-centre retrospective study spanned eight consecutive years and included all patients who underwent both FDG PET/CT and CT-guided bone biopsy because of the suspicion of malignancy. The positive predictive value (PPV) for malignancy was calculated, and different patient and imaging characteristics were compared between malignant and benign bone lesions.

RESULTS

Of 102 included patients with bone lesions that all showed FDG uptake exceeding mediastinal uptake, bone biopsy showed a malignant lesion in 91 patients, yielding a PPV for malignancy of 89.2 % (95 % CI 81.7 - 93.9 %). In the 94 patients with bone lesions that showed FDG uptake exceeding liver uptake, bone biopsy showed a malignant lesion in 83 patients, yielding a PPV for malignancy of 88.3 % (95 % CI 80.1 - 93.5 %). Higher age, bone marrow replacement of the lesion seen on CT, expansion of the lesion seen on CT, and presence of multifocal lesions on FDG PET/CT were significantly more frequent in patients with malignant lesions than in those with benign bone lesions (P = 0.044, P = 0.009, P = 0.015, and P = 0.019, respectively). Furthermore, there was a trend towards a higher incidence of cortical destruction (P = 0.056) and surrounding soft tissue mass (P = 0.063) in patients with malignant bone lesions.

CONCLUSION

The PPV for malignancy of suspicious bone lesions identified on FDG PET/CT is not sufficiently high to justify changes in patient management without histopathological confirmation. Nevertheless, ancillary patient and imaging characteristics may increase the likelihood of a malignant bone lesion.

Dual time point fluorodeoxyglucose positron emission tomography/computed tomography in differentiation between malignant and benign lesions in cancer patients. Does it always work?

OBJECTIVES

Assess the added value of dual time point F-18-fluorodeoxyglucose positron emission tomography/computed tomography (DTP F-18-FDG-PET/CT) in the differentiation of malignant from a benign lesion in cancer patients.

MATERIALS AND METHODS

Totally, 140 F-18-FDG PET/CT scans of 60 cancer patients who underwent DTP protocol (early whole body PET/CT [E] at 60 min [range, 45-76 min] and delayed limited PET/CT [D] on areas of interest at 120 min [range, 108-153 min] after the tracer injection) were retrospectively reviewed. Visual and semi-quantitative analysis was performed on both early and delayed images. All findings were confirmed by histopathology and/or at least 3 months follow-up (F-18-FDG PET/CT, CT, or magnetic resonance imaging). The result was considered true positive (TP) if delayed standardized uptake value (SUV) of suspicious lesions increased and confirmed to be malignant, false positive (FP) if delayed SUV increased and confirmed to be benign, true negative (TN) if delayed SUV unchanged or decreased and confirmed to be benign, and false negative (FN) if delayed SUV unchanged or decreased and confirmed to be malignant.

RESULTS

A total of 164 suspicious lesions were detected (20 presacral lesions, 18 lung nodules, 18 Hodgkin's disease (HD) lesions, 16 rectal lesions, 16 head and neck (H and N) lesions, 14 hepatic lesions, 14 non-Hodgkin's lymphoma (NHL) lesions, 12 mediastinal lymph nodes (LNs), 10 focal gastric uptake, 10 soft tissue lesions, 8 breast lesions, 4 peritoneal nodule, and 4 others). Sixty-four lesions were pathologically confirmed, and 100 lesions were confirmed based on 3-6 months follow-up. There were 62 TP lesions, 44 FP, 58 TN and no FN results. The overall sensitivity was 100% of DTP F-18-FDG PET/CT in detecting suspicious lesions. The specificity was 57% in differentiating malignant from benign lesions, and the accuracy was 73%. Positive predictive value was 59%, negative predictive value (NPV) 100%. All hepatic lesions were TP. Accuracy in metastatic hepatic lesions HD, presacral soft tissue, lung nodules, H, and N cancer, breast cancer, NHL and mediastinal LN was100%, 88.8%, 80%, 78%, 75%, 75%, 71%, and 33.3%, respectively.

CONCLUSIONS

DTP F-18-FDG-PET/CT protocol does not always work in differentiation between benign and malignant lesions. However; it has high NPV, and promising results was noted in hepatic lesions, lymphoma, and recurrent rectal cancer.

The role of bone marrow biopsy and FDG-PET/CT in identifying bone marrow infiltration in the initial diagnosis of high grade non-Hodgkin B-cell lymphoma and Hodgkin lymphoma. Accuracy in a multicenter series of 372 patients

Bone marrow infiltration (BMI), categorized as an extra-nodal site, affects stage and is associated with poor prognosis in newly diagnosed lymphoma patients. We have evaluated the accuracy of PET/CT and bone marrow biopsy (BMB) to assess BMI in 372 lymphoma patients [140 Hodgkin Lymphoma (HL) and 232 High Grade B-cell non-Hodgkin Lymphoma (HG B-NHL), among them 155 Diffuse Large B-Cell Lymphoma (DLCL)]. For HL cases, and taking into account PET/CT, sensitivity, negative predictive value (NPV) and accuracy were 96.7, 99.3, and 99.3% while those of BMB were 32.3, 83.8, and 85%, respectively. For HG B-NHL and considering PET/CT, sensitivity, NPV, and accuracy were 52.7, 81.7, and 84.1%, while those of BMB were 77.6, 90.2, and 90.7%, respectively. In the HG B-NHL group, 25 patients would have been under-staged without BMB. These results lead us to recommend PET/CT and the avoidance of BMB to assess BMI in HL. In the case of HG B-NHL, bone marrow status should be assessed firstly by means of PET/CT; only in either focal or diffuse PET/CT with low borderline SUV max values or in negative cases, should BMB be carried out afterwards. In the HG B-NHL setting and at the present moment, both techniques are complementary.

Dual-phase 18F-FDG PET/CT imaging in the characterization of pancreatic lesions: does it offer prognostic information?

OBJECTIVE

The primary aim of our prospective study was to evaluate the usefulness of dual-phase F-fluoro-deoxy-glucose PET/computed tomography (F-FDG PET/CT) in the characterization of pancreatic masses. The secondary aim was to assess whether delayed imaging revealed any prognostic information.

MATERIALS AND METHODS

Fifty patients with periampullary or pancreatic masses on conventional imaging were included in this study. Early and delayed PET/CT was performed, followed by pathological examination in all patients. PET/CT parameters including uptake pattern, SUVearly, SUVdelayed, lesion to background ratio (L/B), and retention index (RI) were assessed for their ability to differentiate benign from malignant lesions. Patients with malignant lesions were followed up for a median duration of 26 months. The association of 11 variables with survival was analyzed by univariate and multivariate methods.

RESULTS

Thirty-one patients had malignant lesions and 19 had benign lesions. The mean SUVearly, L/B, SUVdelayed, and RI between the malignant and benign lesions were statistically significant. The F-FDG uptake pattern of the lesions had higher sensitivity (93.5%) and specificity (100%) compared with RI (cutoff 25.7%) (84 and 37%, respectively) for diagnosing malignancy (P<0.05). In univariate analysis both RI (>18.7%) and tumor size (>2.6 cm) predicted significantly poor survival, whereas in multivariate analysis RI (P=0.04) was the only predictor of poor survival.

CONCLUSION

Dual-phase F-FDG PET/CT is not useful in characterizing pancreatic masses as it cannot differentiate benign from malignant lesions, and focal uptake on early PET imaging is the best indicator of malignancy. A possible benefit in performing a delayed scan is that a high RI (>18.7) can predict poor survival and hence may be useful in treatment planning.

Positron emission tomography/computed tomography for bone tumors (Review)

The aim of the present study was to investigate positron emission tomography (PET)/computed tomography (CT) and its applications for the diagnosis and treatment of bone tumors. The advantages and disadvantages of PET/CT were also evaluated and compared with other imaging methods and the prospects of PET/CT were discussed. The PubMed, Medline, Elsevier, Wanfang and China International Knowledge Infrastructure databases were searched for studies published between 1995 and 2013, using the terms 'PET/CT', 'positron emission tomography', 'bone tumor', 'osteosarcoma', 'giant cell bone tumor' and 'Ewing sarcoma'. All the relevant information was extracted and analyzed. A total of 73 studies were selected for the final analysis. The extracted information indicated that at present, PET/CT is the imaging method that exhibits the highest sensitivity, specificity and accuracy. Although difficulties and problems remain to be solved, PET/CT is a promising non-invasive method for the diagnostic evaluation of and clinical guidance for bone tumors.

Liver standardized uptake value corrected for lean body mass at FDG PET/CT: effect of FDG uptake time

OBJECTIVE

The objective of this study is to establish the magnitude change and interreader reliability of the liver standardized uptake value corrected for lean body mass (SULmean) in dual-time-point imaging at 1 and 2 hours and 1 and 4 hours.

PATIENTS AND METHODS

Early and delayed FDG PET/CT scans were included for 28 patients (13 men and 15 women) who had normal liver by CT or ultrasound. The average uptake time between the early and delayed scans were 55 minutes (range, 44-69 minutes) for pancreatic adenocarcinoma patients (n = 19) and 184 minutes (range, 140-197 minutes) for neurofibromatosis patients (n = 9). A 30-mm-diameter spherical volume of interest was placed within the right lobe of the liver above, below, and at the level of the main portal vein by 2 independent readers. Correlation coefficients, analysis of variance, intraclass correlation coefficient, and Bland-Altman analysis were performed.

RESULTS

The mean liver SULmean was between 1.39 and 1.42 and between 1.28 and 1.3 in early and delayed images, respectively (P = 0.001). There is time-dependent reduction in the mean liver SULmean at 2-hour (7%-8%) and 4-hour uptake time (15%-21%) compared with 1-hour uptake time. The correlation coefficient between delayed uptake time and liver SULmean reduction is 0.39 to 0.41 at the upper aspect of the liver. The intraclass correlation coefficient for 2 readers varied between 0.997 and 0.998 and between 0.995 and 0.999 in early and delayed images, respectively (P = 0.001).

CONCLUSIONS

There is time-dependent reduction of mean liver SULmean, about 7% to 8% within the clinically relevant FDG uptake time, in the same patient with excellent interreader agreement in early and delayed images within the right lobe of the liver. Therefore, liver SULmean could represent a useful reference parameter in quantitative analysis of dual-phase FDG PET/CT in malignancy or atypical infection/inflammatory disease. Furthermore, it may be suitable as a normalization factor in currently available formulae quantifying therapy response on PET imaging.

Pulmonary metastasis of giant cell tumor of bones

Giant cell tumor of bone (GCTB) accounts for 5% of primary skeletal tumors. Although it is considered to be a benign lesion, there are still incidences of pulmonary metastasis. Pulmonary metastasis of GCTB may be affected by tumor grading and localization as well as the age, gender and overall health status of the patient. Patients with local recurrence are more likely to develop pulmonary metastasis of GCTB. High expression of some genes, cytokines and chemokines may also be closely related to the metastatic potential and prognosis of GCTB. The treatment of the primary GCTB is key to the final outcome of the disease, as intralesional curettage has a significantly higher local recurrence and pulmonary metastasis rate than wide resection. However, even patients with pulmonary metastasis seem to have a good prognosis after timely and appropriate surgical resection. It is hoped that with the development of novel surgical methods and drugs, pulmonary metastasis of GCTB can be prevented and treated more effectively.

18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals derived from a single-institution 18F-FDG-directed surgery experience: feasibility and quantification of 18F-FDG accumulation within 18F-FDG-avid lesions and background tissues

Background

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is a well-established imaging modality for a wide variety of solid malignancies. Currently, only limited data exists regarding the utility of PET/CT imaging at very extended injection-to-scan acquisition times. The current retrospective data analysis assessed the feasibility and quantification of diagnostic ¹⁸F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals.

Methods

¹⁸F-FDG-avid lesions (not surgically manipulated or altered during ¹⁸F-FDG-directed surgery, and visualized both on preoperative and postoperative ¹⁸F-FDG PET/CT imaging) and corresponding background tissues were assessed for ¹⁸F-FDG accumulation on same-day preoperative and postoperative ¹⁸F-FDG PET/CT imaging. Multiple patient variables and ¹⁸F-FDG-avid lesion variables were examined.

Results

For the 32 ¹⁸F-FDG-avid lesions making up the final ¹⁸F-FDG-avid lesion data set (from among 7 patients), the mean injection-to-scan times of the preoperative and postoperative ¹⁸F-FDG PET/CT scans were 73 (±3, 70-78) and 530 (±79, 413-739) minutes, respectively (P < 0.001). The preoperative and postoperative mean ¹⁸F-FDG-avid lesion SUV_max values were 7.7 (±4.0, 3.6-19.5) and 11.3 (±6.0, 4.1-29.2), respectively (P < 0.001). The preoperative and postoperative mean background SUV_max values were 2.3 (±0.6, 1.0-3.2) and 2.1 (±0.6, 1.0-3.3), respectively (P = 0.017). The preoperative and postoperative mean lesion-to-background SUV_max ratios were 3.7 (±2.3, 1.5-9.8) and 5.8 (±3.6, 1.6-16.2), respectively, (P < 0.001).

Conclusions

¹⁸F-FDG PET/CT oncologic imaging can be successfully performed at extended injection-to-scan acquisition time intervals of up to approximately 5 half-lives for ¹⁸F-FDG while maintaining good/adequate diagnostic image quality. The resultant increase in the ¹⁸F-FDG-avid lesion SUV_max values, decreased background SUV_max values, and increased lesion-to-background SUV_max ratios seen from preoperative to postoperative ¹⁸F-FDG PET/CT imaging have great potential for allowing for the integrated, real-time use of ¹⁸F-FDG PET/CT imaging in conjunction with ¹⁸F-FDG-directed interventional radiology biopsy and ablation procedures and ¹⁸F-FDG-directed surgical procedures, as well as have far-reaching impact on potentially re-shaping future thinking regarding the “most optimal” injection-to-scan acquisition time interval for all routine diagnostic ¹⁸F-FDG PET/CT oncologic imaging.

Imaging-guided biopsy of (18)F-FDG-avid extrapulmonary lesions: do lesion location and morphologic features on CT affect the positive predictive value for malignancy?

OBJECTIVE

The purpose of our study was to analyze the effect of lesion location and morphologic appearance on CT on the positive predictive value (PPV) for malignancy of all extrapulmonary lesions that were (18)F-FDG avid on PET/CT and that were biopsied under imaging guidance.

MATERIALS AND METHODS

Between January 2004 and December 2010, 227 patients underwent imaging-guided biopsy of 231 PET-positive extrapulmonary lesions with diagnostic pathologic results. The PET PPV for malignancy was retrospectively calculated and stratified according to lesion location and morphologic appearance.

RESULTS

The overall PET PPV for malignancy was 72%. Inflammatory processes accounted for the majority of benign biopsy results. Lesion location significantly affected the PPV (p < 0.001). Bone (96%) and liver (90%) lesions had significantly higher PPVs for malignancy compared with other locations, whereas lymph nodes (60%) had a significantly lower PPV for malignancy. Lesions that were morphologically suspicious and morphologically benign according to CT findings alone were associated with PPVs of 74% and 57%, respectively (p = 0.05). FDG-avid subcentimeter lymph nodes (n = 8) had a PPV for malignancy of 38%.

CONCLUSION

Over half of PET-avid morphologically benign-appearing lesions and one third of PET-avid subcentimeter lymph nodes were found to be malignant at biopsy, suggesting that benign morphologic appearance alone should not preclude further workup of a PET-positive lesion. Biopsies of FDG-avid lesions in liver and bone yielded high rates of true malignancy, whereas biopsies of lymph nodes yielded a lower rate of malignancy compared with other lesion locations.

Dual-time-point FDG PET/CT for the evaluation of pediatric tumors

OBJECTIVE

The utility of dual-time-point (18)F-FDG PET/CT in differentiating benign from malignant processes in pediatric patients was assessed.

SUBJECTS AND METHODS

Twenty-one patients (13 girls and eight boys; age range, 1-17 years) with suspected malignancy underwent dual-time-point FDG PET/CT. Scan 1 was performed at approximately 60 minutes after i.v. injection of 5.18 MBq/kg of FDG, and scan 2 was performed at 121 ± 43 minutes after the first scan. Regions of interest were overlaid onto each non-attenuated-corrected image, and semiquantitative analysis was performed using the standardized uptake value (SUV) obtained from early and delayed images. A retention index was calculated according to the following equation: [(delayed SUV - early SUV) / early SUV] × 100. Results were compared prospectively in relation to pathologic examination or other conventional radiologic imaging or clinical follow-up. A retention index of 10% or higher was chosen as a cutoff for differentiating malignant from benign entities.

RESULTS

For patients with malignant disease, the average SUV increased from 7.3 ± 1.2 to 10.9 ± 2.7 between the two time points, whereas the SUV changed from 4.5 ± 0.8 to 4.2 ± 1.0 for patients with benign lesions. The average retention index was 37.1% ± 10.8% for patients with malignant lesions versus -9.9% ± 7.1% for benign lesions (p < 0.01). With a cutoff value of 10% or higher for the retention index, the sensitivity and specificity of dual-time-point FDG PET/CT were 77% and 80%, respectively.

CONCLUSION

These data show that dual-time-point FDG PET/CT is useful in distinguishing malignant from benign processes in pediatric patients.

Cavernous hemangioma of the ilium mimicking aggressive malignant bone tumor with increased activity on (18)F-FDG PET/CT

Osseous hemangioma is a benign vascular tumor, and it usually occurs in the vertebrae and the skull. However, hemangiomas of flat bones are rare, and there are very few reports that describe the radiologic findings of osseous hemangioma of the ilium. We report a unique case of large cavernous hemangioma mimicking a chondrogenic malignant bone tumor originated from the ilium in a 22-year-old female. The mass showed stippled calcifications, heterogeneous enhancement with thick septa and enhanced soft tissue components on CT and MR, and also this mass demonstrated heterogeneous 2-fluoro [fluorine-18]-2-deoxy-D-glucose (¹⁸F-FDG) uptake on ¹⁸F-FDG PET/CT.