Single photon emission tomography/computed tomography (SPET/CT) and positron emission tomography/computed tomography (PET/CT) to image cancer

Hybrid systems associating the sharpness of anatomic images coming from computed tomography (CT) and radionuclide functional imaging (SPET or PET) are opening a new era in oncology. This multimodal imaging method is now routinely used for the diagnosis, extent, follow up, treatment response and detection of occult disease in different types of malignancies with a significant impact on the treatment strategy leading for a change for more than 68% of all investigated patients.     

~(18)F-FDG PET/CT结直肠代谢活跃灶分型对于良恶性判断的价值

背景与目的:结直肠迁延迂曲且位置不固定,肠管自身蠕动造成肠壁厚度变化。结直肠自身葡萄糖代谢不稳定,平滑肌蠕动、腺体分泌活动、痉挛、炎症等均可造成代谢异常。这些解剖和生理代谢方面的因素均会给18F-FDGPET/CT的正确诊断带来一定困难。本研究探讨18F-FDGPET/CT结直肠代谢活跃灶的影像特点及对于临床诊断的价值。方法:将74例患者共118个18F-FDGPET/CT发现的结直肠代谢活跃灶依据代谢及形态特点分为6型,局灶/CT+型、局灶/CT-型、节段/CT+型、节段/CT-型、弥漫/CT+型、弥漫/CT-型。将各分型情况与定性资料进行对比分析,采用R×C列联表χ2检验进行统计学分析。结果:118个结直肠代谢活跃灶定性为恶性共50个、非恶性68个,其中局灶/CT+型共30个(恶性23个、非恶性7个)、局灶/CT-型35个(恶性22个、非恶性13个)、节段/CT+型4个(恶性4个、非恶性0个)、节段/CT-型35个(恶性1个、非恶性34个)、弥漫/CT+型0个、弥漫/CT-型14个(恶性0个、非恶性14个)。节段/CT-型、弥漫/CT-型的非恶性病变发生率(97.1%、100%)和节段/CT+型的恶性病变...     

Routine positron emission tomography and positron emission tomography/computed tomography in melanoma staging with positive sentinel node biopsy is of limited benefit

Positron emission tomography (PET) is increasingly used for the staging and management of melanoma. The aim of this study was to evaluate the role of PET or PET/ computed tomography (CT) as a routine procedure in patients with positive sentinel node biopsy (SNB). Thirty patients with melanoma of Breslow thickness greater than 1 mm who had PET or PET/CT scans performed within 100 days after a positive SNB were reviewed retrospectively. Two patients (6%) had a positive PET scan, none of which were melanoma related. The first patient had a synchronous neuroendocrine thyroid tumour and the second patient had increased uptake in the chest wall, which proved to be old trauma. Lymph node dissection was positive in five cases (16%). With a median follow-up of 24 months, 21 patients remained disease free. In none of the 30 cases did the early PET scan after a positive SNB alter subsequent melanoma management. The role of PET scanning soon after a positive sentinel node biopsy seems to be of limited benefit. It is questionable whether any imaging is beneficial at this stage. The results of this review suggest that PET scanning might not be indicated for this group of patients.     

Combined positron emission tomography/computed tomography in sunitinib therapy assessment of patients with metastatic renal cell carcinoma

Aim

To assess the clinical benefit of combined functional imaging with [¹⁸F]2-fluoro-2-deoxy-d-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with metastatic renal cell carcinoma (mRCC) treated with the tyrosine kinase inhibitor sunitinib.

Materials and methods

Fourteen patients with mRCC were prospectively enrolled in this study. All patients underwent PET/CT before receiving at least two cycles of sunitinib treatment. Three months after the onset of sunitinib treatment, a second PET/CT was carried out. The metabolic response evaluated from the PET (standard uptake value; SUV) was compared with the CT component of the PET/CT. The Response Evaluation Criteria in Solid Tumours criteria were used to assess the CT response and modified European Organization for Research and Treatment of Cancer criteria were used to assess the PET response.

Results

Three main results were obtained: (1) Patients with relatively low 18F-FDG uptake before treatment (SUV < 5) had a longer progression-free survival than those with a relatively high 18F-FDG uptake (P = 0.006). (2) Patients with a partial metabolic response or stable metabolic disease after two courses of sunitinib had improved prognosis as compared with those with progressive metabolic disease (P = 0.031). (3) There was a clear discrepancy between PET and CT as a tool for the evaluation of treatment response after two courses of sunitinib. PET indicated progressive disease in three patients, a partial response in six patients and stable disease in four patients. In contrast, CT concluded with progression in only one patient and stable disease in all other patients.

Conclusion

In patients with mRCC, a high baseline 18F-FDG uptake indicates aggressive disease, and the degree of reduction in 18F-FDG uptake after sunitinib treatment adds valuable prognostic information. Hence, the inclusion of PET results seems to improve the clinical counselling of patients with mRCC. Larger studies are needed to confirm these findings.     

18F]FDG positron emission tomography/computed tomography and multidetector computed tomography roles in thymic lesion treatment planning

RATIONALE: Thymic masses may represent an unsolved diagnostic problem which often require surgical procedures for an accurate staging. A non-invasive way to determine the nature of thymic lesions would help identify the patients which are true candidates for surgery. Our retrospective study aims to assess multidetector computed tomography and 2-[(18)F]fluoro-2-deoxyglucose positron emission tomography/computed tomography ([(18)F]FDG-PET/CT) capacity to distinguish benign from malignant thymic lesions. METHODS: Helical multidetector CT (MDCT) and [(18)F]FDG-PET/CT of twenty consecutive patients presenting with a thymic mass at our Institute were retrospectively analyzed. MDCT scans were focused on morphologic features and invasiveness characteristics. Qualitative and semi-quantitative analyses by maximum standardized uptake value corrected for body weight (SUVbw max) were performed on [(18)F]FDG-PET/CT. In all cases, readers were blinded to pathology findings. Both imaging techniques were correlated to final pathology. Student's t-test was performed on SUVbw max stratified for thymic epithelial tumors. RESULTS: In the group of benign lesions MDCT correctly identified well-defined margins of masses in 8 out of 8 patients whereas [(18)F]FDG-PET/CT was negative in 7 out of 8 patients. Among malignant lesions MDCT revealed mediastinum fat or infiltration of adjacent organs in 10/12 patients. On the other hand [(18)F]FDG-PET/CT showed increased radiotracer uptake in 12/12 patients. CONCLUSIONS: MDCT and [(18)F]FDG-PET/CT alone are not able to differentiate the nature of thymic lesions. However, they are two non-invasive complementary techniques which can be used to differentiate benign from high-risk malignant thymic lesions. These findings should be taken into account before surgery is performed as a diagnostic procedure.     

Prospective comparison of 18F-fluorodeoxyglucose positron emission tomography/computed tomography and whole-body magnetic resonance imaging in staging of advanced malignant melanoma

The aim of our study was to compare the overall and site-based accuracy and impact on patient management of positron emission tomography/computed tomography (PET/CT) and whole-body (wb) magnetic resonance imaging (MRI) in staging of advanced melanoma. In a prospective blinded study, 64 patients with American Joint Committee on Cancer (AJCC) stage III/IV melanoma underwent 18F-fluorodeoxyglucose PET/CT and wbMRI. In total 420 lesions were evaluated. The overall accuracy of PET/CT was 86.7% compared to 78.8% for wbMRI (P=0.0007). PET/CT was significantly more accurate in N-staging and detecting of skin and subcutaneous metastases, whereas wbMRI was more sensitive in detecting liver, bone and brain metastases. WbMRI was less sensitive but more specific than PET/CT in classifying pulmonary lesions. In 41 patients (64%) whole-body imaging caused changes of treatment. Whole-body staging of patients with advanced melanoma is most accurate by combining wbPET/CT and organ-specific wbMRI including a brain, liver and bone marrow protocol.     

Clinicopathological correlation for the role of fluorodeoxyglucose positron emission tomography computed tomography in detection of choroidal malignant melanoma

Background

The purpose of this study was to redefine the role of whole-body 2-[¹⁸F]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography fused with computed tomography (PET/CT) in the clinical diagnosis of choroidal malignant melanoma.

Methods

The study design was a retrospective case series involving 7 consecutive patients with choroidal malignant melanoma who underwent enucleation to reach the final pathological diagnosis. FDG-PET/CT was performed together with magnetic resonance imaging and ophthalmological examinations before the surgery. The area, thickness, longest diameter, and circumference of the tumor mass were measured on pathological sections, and were correlated with maximum standardized uptake values (SUVmax) of the tumors on FDG-PET/CT.

Results

Abnormally high uptake of FDG was noted in the affected eyes of 5 patients, but not in the eyes of 2 patients. The 5 patients with high uptake showed nodular tumors extruding into the vitreous cavity while the 2 patients with absence of uptake showed diffusely infiltrating tumors in the wide area of the choroid with or without a small mushroom-like protrusion. One patient with diffuse infiltration showed concurrent liver metastases with high uptake on PET/CT while another patient with a nodular tumor developed liver metastases a year later. The tumors with higher SUVmax had a tendency to have a wider area and greater thickness on pathological sections (ρ = 0.775, P = 0.0557, Spearman rank correlation test).

Conclusions

FDG-PET/CT showed correlation of the uptake with tumor sizes but was limited in detecting diffusely infiltrating tumors in the choroid without nodular formation.     

Comparison between positron emission tomography and computed tomography in the use of the assessment of esophageal carcinoma

BACKGROUND: The role and potential value of positron emission tomography (PET) scanning in certain tumors has been widely investigated in recent years. The authors retrospectively assessed the performance of 18-F-fluorodeoxyglucose (FDG)-PET in the assessment of esophageal squamous cell carcinoma (SCC). METHODS: The results using PET were compared with those using computed tomography (CT), and these were correlated with the pathologic findings. The authors studied 32 patients with thoracic esophageal SCC who had undergone radical esophagectomy. RESULTS: Uptake of FDG in the primary tumor was found in 25 of the 32 (78.1%) cases. Comparison of the FDG uptake and the clinicopathologic findings showed that there was a significant association between the FDG uptake and each of the depth of tumor invasion (P < 0.05), occurrence of lymph node metastasis (P < 0.01), and lymphatic invasion (P < 0.01). The survival rate in cases with high FDG uptake (standardized uptake value [SUV], >3) was significantly lower than that in cases with low FDG uptake (SUV, < 3; P < 0.05). In the evaluation of lymph node staging by the detection of lymph node metastasis, FDG-PET showed 77.8% sensitivity, 92.9% specificity, and 84.4% accuracy, and CT scanning showed 61.1% sensitivity, 71.4% specificity, and 65.6% accuracy. Positron emission tomography scanning showed a high degree of accuracy in the neck, upper thoracic, and abdominal regions. However, in the mid- and lower thoracic regions, the sensitivity was very low. The smallest lymph node metastasis that was detected by FDG-PET imaging was 6 mm. The average size of lymph node metastasis that was undetected by FDG-PET scanning was 7.3 mm (range, 1-17 mm). CONCLUSIONS: In conclusion, FDG-PET may be used as a noninvasive diagnostic technique in assessing the aggressiveness of the tumor and the prognosis in patients with esophageal SCC. During the preoperative diagnostic procedures, the sensitivity, specificity, and accuracy of lymph node staging is higher with FDG-PET than with CT imaging. In view of the high specificity of FDG-PET, it also gives useful information to guide the choice of treatment of esophageal carcinoma.     

Characteristics of advantages of positron emission tomography over computed tomography for N-staging in lung cancer patients

OBJECTIVE: We analyzed the characteristics of advantages of positron emission tomography (PET) over computed tomography (CT) for N-staging in lung cancer patients. METHODS: Preoperative PET and CT scans were performed for 2057 lymph node stations in 205 patients with peripheral-type lung cancer. The advantages of PET over CT for N-staging were analyzed among lymph node locations and histological subtypes. RESULTS: The pathological N-stages were N0 in 143 patients, N1 in 31, N2 in 24 and N3 in 7. PET was able to diagnose N0, N2 and N3 diseases more accurately than CT (P=0.03, 0.01 and 0.02, respectively), but there was no significant difference between the two modalities for N1 disease. In the upper mediastinal lymph node stations, both false-negative and false-positive were significantly less frequent with PET than with CT (P=0.001). In the lower mediastinal and supra clavicle lymph nodes, PET showed a lower frequency of false-negative than CT (P=0.04 and 0.003, respectively), but there was no significant difference in the frequency of false-positive between the two modalities. Among histological types, PET could stage adenocarcinoma with less frequent false-negative and squamous cell carcinoma with less frequent false-positive than CT (P=0.02 and 0.005, respectively). CONCLUSION: For N-staging, PET was superior to CT for the following: (1) more accurate for N0, N2 and N3 diseases but not for N1; (2) lower frequency of false-positive in the upper mediastinal nodes; and (3) lower frequencies of false-negative in adenocarcinoma and false-positive in squamous cell carcinoma. Recognizing these advantages of PET could make the N-staging of lung cancer more accurate.     

Impact of positron emission tomography with computed tomography for image-guided radiotherapy

Therapeutic effectiveness in radiotherapy is partly related to correct staging of the disease and then precise therapeutic targeting. Positron emission tomography (PET) allows the stage of many cancers to be determined and therefore is essential before deciding on radiation treatment. The definition of the therapeutic target is essential to obtain correct tumour control and limit side effects. The part of adaptive radiotherapy remains to be defined, but PET by its functional nature makes it possible to define the prognosis of many cancers and to consider radiotherapy adapted to the initial response allowing an increase over the entire metabolic volume, or targeted at a subvolume at risk per dose painting, or with a decrease in the dose in case of good response at interim assessment.     

Clinical implications of 18F-fluorodeoxyglucose positron emission tomography/computed tomography at delayed phase for diagnosis and prognosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) has a poor prognosis, and conventional imaging modalities do not reflect the prognosis of MPM. In this study, the clinical significance of 18F-fluorodeoxyglucose positron emission tomography/computed tomography fusion imaging (18F-FDG PET/CT) was evaluated for the differential diagnosis, staging and prognosis in MPM patients. Ninety patients who underwent 18F-FDG PET/CT scanning due to a clinical diagnosis or suspicion of MPM prior to therapy were reviewed. Of 90 patients, 31 were pathologically diagnosed as MPM. Maximum standardized uptake values (SUVmax) were semi-quantitatively obtained from PET/CT 60 min (early phase) and 120 min (delayed phase) after injection of 18F-FDG, and the clinicopathological correlations with the level of SUVmax obtained from PET/CT were examined. The survival curves of MPM patients were plotted according to the methods of Kaplan-Meier. The prognostic implications of the level of SUVmax were estimated by t-test. PET/CT scan showed intense abnormal FDG uptake (SUVmax>2.0) in the pleural lesions of all 31 MPM patients at delayed phase, while it showed abnormal FDG uptake in 30 (97%) patients at early phase. In all 31 MPM patients, the values of SUVmax at delayed phase were higher than those at the early phase. PET/CT also indicated metastasis in the lymph node in 7 patients (23%) and in the systemic lesions in 8 patients (26%) with MPM. Twenty-three MPM patients with high SUVmax, whose prognosis was apparent, showed significantly poorer prognosis in both early and delayed phase (respectively, p=0.03 and p=0.01, t-test). The results showed that 18F-FDG PET/CT at delayed phase is very useful for the diagnosis of pleural diseases, and SUVmax on PET/CT in the delayed phase is a more reliable prognostic factor than that in the early phase. High uptake of 18F-FDG PET/CT may be a predictive factor of prognosis in MPM patients.     

Etiology of solitary extrapulmonary positron emission tomography and computed tomography findings in patients with lung cancer.

PURPOSE: The aim of this prospective study was to assess the incidence and the nature of solitary extrapulmonary [18F] fluorodeoxyglucose (FDG) accumulations in patients with non-small-cell lung cancer (NSCLC) staged with integrated positron emission tomography and computed tomography (PET/CT) and to evaluate the impact on management. PATIENTS AND METHODS: A total of 350 patients with NSCLC underwent whole-body PET/CT imaging. All solitary extrapulmonary FDG accumulations were evaluated by histopathology, further imaging, or clinical follow-up. RESULTS: PET/CT imaging revealed extrapulmonary lesions in 110 patients. In 72 patients (21%), solitary lesions were present. A diagnosis was obtained in 69 of these patients, including 37 (54%) with solitary metastases and 32 (46%) with lesions unrelated to the lung primary. Histopathologic examinations of these 32 lesions revealed a second clinically unsuspected malignancy or a recurrence of a previous diagnosed carcinoma in six patients (19%) and a benign tumor or inflammatory lesion in 26 patients (81%). The six malignancies consisted of carcinoma of the breast in two patients, and carcinoma of the orbit, esophagus, prostate, and non-Hodgkin's lymphoma in one patient each. Benign tumors and inflammatory lesions included eight colon adenomas, four Warthin's tumors, one granuloma of the lower jaw, one adenoma of the thyroid gland, one compensatory muscle activity due to vocal chord palsy, two occurrences of arthritis, three occurrences of reflux esophagitis, two occurrences of pancreatitis, two occurrences of diverticulitis, one hemorrhoidal inflammation, and one rib fracture. CONCLUSION: Solitary extrapulmonary FDG accumulations in patients with newly diagnosed lung cancer should be analyzed critically for correct staging and optimal therapy, given that up to half of the lesions may represent unrelated malignancies or benign disease.     

Initial staging impact of fluorodeoxyglucose positron emission tomography/computed tomography in locally advanced breast cancer

Purpose.

Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) may reveal distant metastases more accurately than conventional imaging (CT, skeletal scintigraphy, chest radiography). We hypothesized that patients diagnosed with stage III noninflammatory breast cancer (non-IBC) and IBC by conventional imaging with PET/CT have a better prognosis than patients diagnosed without PET/CT.

Patients and Methods.

We retrospectively identified 935 patients with stage III breast cancer in 2000–2009. We compared the relapse-free survival (RFS) and overall survival (OS) times of patients diagnosed by conventional imaging with those of patients diagnosed by conventional imaging plus PET/CT. Univariate and multivariate Cox proportional hazards regression models were used to assess associations between survival and PET/CT.

Results.

RFS and OS times were not significantly different between patients imaged with PET/CT and those imaged without PET/CT. However, the RFS time in IBC patients was significantly different between patients imaged with PET/CT and those imaged without PET/CT on both univariate (hazard ratio [HR], 0.43; p = .014) and multivariate (HR, 0.33; p = .004) analysis. There was a trend for a longer OS duration in IBC patients imaged with PET/CT.

Conclusion.

Among IBC patients, adding PET/CT to staging based on conventional imaging might detect patients with metastases that were not detected by conventional imaging. The use of conventional imaging with PET/CT for staging in non-IBC patients is not justified on the basis of these retrospective data. The use of conventional imaging plus PET/CT in staging IBC needs to be studied prospectively to determine whether it will improve prognosis.     

18F‐fluoro‐2‐deoxy‐D‐glucose positron emission tomography and positron emission tomography/computed tomography imaging of malignant pleural mesothelioma*

Malignant pleural mesothelioma (MPM) is the most common primary pleural tumor and its incidence is rising. Its diagnosis, staging and response assessment are challenging for imaging. Integrated positron emission tomography (PET)/CT increases the accuracy of overall staging in patients with mesothelioma and improves the selection of patients for curative surgical resection. It is particularly useful in identifying occult distant metastases. It may be used to predict prognosis and to assess the metabolic response to therapy.     

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

BACKGROUND:

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

METHODS:

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

RESULTS:

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

CONCLUSIONS:

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

Lymph node uptake of 18F-fluorodeoxyglucose detected with positron emission tomography/computed tomography mimicking malignant lymphoma in a patient with Kikuchi disease

[18]F-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is sensitive in detecting a variety of malignancies; however, the specificity is low in differential infections or inflammatory diseases from tumors. We present the case of a female with right cervical lymphadenopathy and fever for 3 weeks who underwent an 18F-FDG PET/CT scan. The imaging showed multiple lymph node enlargement and agglomeration with increased metabolic activity even with the involvement in the abdomen, giving the impression of malignant lymphoma. However, biopsy of the affected nodes proved it to be Kikuchi-Fujimoto disease and the patient was cured after steroid therapy.