Diagnostic accuracy of contrast-enhanced FDG-PET/CT in primary staging of cutaneous malignant melanoma

Purpose  To evaluate the diagnostic accuracy of contrast-enhanced FDG-PET/CT (ce-PET/CT), PET-only, and CT-only in patients with newly diagnosed and resected cutaneous malignant melanoma. Methods  A final group of 56 patients (mean age 62 years, range 23–86 years; 29 women, 27 men) were staged with ce-PET/CT after resection of the primary tumour. Histopathology as well as clinical follow-up (mean 780 days, range 102–1,390 days) served as the standards of reference. Differences between the staging modalities were tested for statistical significance with McNemar’s test. Results  All imaging procedures provided low sensitivities in the detection of lymph nodes (sensitivity N-stage: PET/CT and PET-only 38.5%; CT-only 23.1%) and distant metastases (sensitivity M-stage: PET/CT 41.7%, PET-only 33.3%, CT-only 25.0%) in initial staging after resection of the primary tumour. No statistically significant differences were detected between the imaging procedures (p > 0.05). PET/CT resulted in an alteration in further treatment in two patients compared to PET-only and in four patients compared to CT-only. Conclusion  All imaging modalities had a low sensitivity on initial staging of patients with malignant melanoma. Thus, close patient follow-up must be considered mandatory.     

Limited value of <Superscript>18</Superscript>F-FDG PET/CT and S-100B tumour marker in the detection of liver metastases from uveal melanoma compared to liver metastases from cutaneous melanoma

Purpose  

The objective of this study was to evaluate the value of ¹⁸F-FDG PET/CT and S-100B tumour marker for the detection of liver metastases from uveal melanoma in comparison to liver metastases from cutaneous melanoma.     

Diagnostic value of PET/CT for the staging and restaging of pediatric tumors

Objective  The objective of this retrospective study was to compare the diagnostic value of 2-[¹⁸F]fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET)/CT versus ¹⁸F-FDG PET and CT alone for staging and restaging of pediatric solid tumors. Methods  Forty-three children and adolescents (19 females and 24 males; mean age, 15.2 years; age range, 6–20 years) with osteosarcoma (n = 1), squamous cell carcinoma (n = 1), synovial sarcoma (n = 2), germ cell tumor (n = 2), neuroblastoma (n = 2), desmoid tumor (n = 2), melanoma (n = 3), rhabdomyosarcoma (n = 5), Hodgkin’s lymphoma (n = 7), non-Hodgkin-lymphoma (n = 9), and Ewing’s sarcoma (n = 9) who had undergone ¹⁸F-FDG PET/CT imaging for primary staging or follow-up of metastases were included in this study. The presence, location, and size of primary tumors was determined separately for PET/CT, PET, and CT by two experienced reviewers. The diagnosis of the primary tumor was confirmed by histopathology. The presence or absence of metastases was confirmed by histopathology (n = 62) or clinical and imaging follow-up (n = 238). Results  The sensitivities for the detection of solid primary tumors using integrated ¹⁸F-FDG PET/CT (95%), ¹⁸F-FDG PET alone (73%), and CT alone (93%) were not significantly different (p > 0.05). Seventeen patients showed a total of 153 distant metastases. Integrated PET/CT had a significantly higher sensitivity for the detection of these metastases (91%) than PET alone (37%; p < 0.05), but not CT alone (83%; p > 0.05). When lesions with a diameter of less than 0.5 cm were excluded, PET/CT (89%) showed a significantly higher specificity compared to PET (45%; p < 0.05) and CT (55%; p < 0.05). In a sub-analysis of pulmonary metastases, the values for sensitivity and specificity were 90%, 14%, 82% and 63%, 78%, 65%, respectively, for integrated PET/CT, stand-alone PET, and stand-alone CT. For the detection of regional lymph node metastases, ¹⁸F-FDG PET/CT, ¹⁸F-FDG PET alone, and CT alone were diagnostically correct in 83%, 61%, and 42%. A sub-analysis focusing on the ability of PET/CT, PET, and CT to detect osseous metastases showed no statistically significant difference between the three imaging modalities (p > 0.05). Conclusion  Our study showed a significantly increased sensitivity of PET/CT over that of PET for the detection of distant metastases but not over that of CT alone. However, the specificity of PET/CT for the characterization of pulmonary metastases with a diameter > 0.5 cm and lymph node metastases with a diameter of <1 cm was significantly increased over that of CT alone.     

Impact of FDG PET on the preoperative staging of newly diagnosed breast cancer

Purpose The main objective of this study was to determine the efficacy of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) to assess the impact of this technique in staging of patients with newly diagnosed breast cancer. Methods Two hundred and seventy-one consecutive patients (median age = 51 ± 11 years) with biopsy-proven primary breast cancer who were examined by FDG PET were enrolled in this prospective preoperative staging study. Whole-body FDG-PET images were acquired approximately 60 min after the intravenous administration of FDG (5.2 MBq/kg). Visual assessment and the maximum standardized uptake value (SUVmax) of breast lesions for semiquantitative analysis were carried out. The PET results were compared with the histopathology results. Results For the tumor, node, metastases (TNM) staging, 240 patients (250 breasts) were considered eligible based on the criteria that were established for this analysis. Significant differences were noted in SUVmax of lesions according to the TNM staging (p < 0.05). The average SUVmax of the primary tumor was calculated in patients with axillary involvement (n = 58) and for the ones without axillary metastasis (n = 79), and SUVmax were 4.1 ± 3.5 and 2.8 ± 2.3, respectively, with a significant difference between the two groups (p = 0.03). PET imaging revealed pathological FDG uptake in 54% (46/85) of patients with axillary lymph node metastases. The sensitivities of FDG PET for detecting axillary lymph node metastasis were found 41% in pN1, 67% in pN2, and 100% in pN3, and the specificity was 89% for pN0 stage. Detection of extra-axillary regional node or distant metastatic lesions revealed by PET scan in 22 of 24 patients resulted in a significant change in the TNM stage. Distant metastasis without axillary lymph node metastasis was noted in 21% (5/24) of patients. The results revealed that FDG PET upgraded TNM stage in 9.2% (22/240) of patients and 7.5% (18/240) of patients were diagnosed as having one or more distant metastases. Conclusion FDG PET was able to identify extra-axillary regional nodal and distant lesions in newly diagnosed patients with breast cancer; FDG PET may alter the staging and management of therapy in patients with newly diagnosed breast cancer.     

Evaluation of [<Superscript>18</Superscript>F]-choline PET/CT for staging and restaging of prostate cancer

Purpose To evaluate the accuracy of [¹⁸F]-choline (FCH) positron emission tomography/computed tomography (PET/CT) for staging and restaging of prostate cancer. Methods FCH PET/CT was performed in 111 patients with prostate cancer using 200 MBq FCH: 43 patients [mean age 63 years; mean prostrate specific antigen (PSA) 11.58 μg/l] were examined for initial staging, and 68 patients (mean age 66.4 years) were examined for restaging (mean PSA 10.81 μg/l). FCH PET/CT results were correlated to histopathology, bone scan, morphology as revealed by magnetic resonance imaging (MRI) and CT, PET/CT follow-up and PSA follow-up after therapy. Results FCH PET/CT scans at initial staging correctly showed no metastases in 36/38 patients undergoing radical surgery, as confirmed by PSA levels <0.1 μg/l 6 months postoperatively. Lymphadenectomy was performed in 24 of these patients, revealing four false FCH-negative lymph nodes (LN). In one patient, only lymphadenectomy was performed since a FCH-positive LN was confirmed by histology. Four patients showed FCH-positive bone metastases, as proven by bone scan. FCH PET/CT scans at restaging correctly revealed local recurrence in 36 patients. No pathological FCH uptake was observed in 11 patients with biochemical recurrence. Twenty-three patients showed FCH-positive LN. Twenty LN were surgically removed in seven patients. Histopathology verified metastases in all LN, but revealed two additional metastastic, FCH-negative LN. Seventeen patients showed FCH-positive bone metastases, as proven by bone scan or MRI. Sensitivity to detect recurrent disease was 86%. Conclusion The results obtained using FCH PET/CT scans for initial N-staging were discouraging, especially in terms of its inability to detect small metastases. Recurrent disease can be localized reliably in patients with PSA levels of >2 μg/l.     

Chemotherapy response assessment in stage IV melanoma patients—comparison of <Superscript>18</Superscript>F-FDG-PET/CT,CT, brain MRI,and tumormarker S-100B

PURPOSE: This study aims to compare the use of 18F-FDG-PET/CT, CT, brain MRI, and tumormarker S-100B in chemotherapy response assessment of stage IV melanoma patients. METHODS: In 25 patients with stage IV melanoma, FDG-PET/CT and S-100B after 2-3 months (three cycles) of chemotherapy was compared with baseline PET/CT and baseline S-100B. Retrospectively, the response was correlated with the outcome. In patients with clinical suspicion for brain metastases, MRI or CCT was performed. RESULTS: There was agreement between FDG-PET/CT and CT regarding response to chemotherapy in all patients. There was a clear trend to a longer OS of PET/CT responders (n=10) compared with PET/CT non-responders (n=15; p=0.072) with remarkably better 1-year OS of 80% compared to 40% (p=0.048). There was a significant longer PFS of PET/CT responders compared with PET/CT non-responders (p=0.002). S-100B was normal at baseline in eight of 22 patients where it was available. Chemotherapy response assessment with S-100B failed to show correlation with OS or PFS. Eleven patients developed brain metastases during treatment, first detected by PET/CT in two and by MRI or CCT in nine of 11 patients. Appearance of brain metastases was associated with a poor survival. CONCLUSIONS: 18F-FDG-PET/CT and CT alone are equally suitable for chemotherapy response assessment in melanoma patients and clearly superior to S-100B. PET/CT responders have better early survival, but this is shortlived due to late therapy failure--often with brain recurrence. Additional brain MRI for therapy response assessment in such high-risk patients is mandatory to detect brain metastases missed by PET/CT.     

Whole-body FDG PET/CT is more accurate than conventional imaging for staging primary breast cancer patients

Purpose

This retrospective study aimed (1) to compare the diagnostic accuracy of whole-body FDG PET/CT for initial breast cancer staging with the accuracy of a conventional, multimodal imaging algorithm, and (2) to assess potential alteration in patient management based on the FDG PET/CT findings.

Methods

Patients with primary breast cancer (106 women, mean age 57?±?13?years) underwent whole-body FDG PET/CT and conventional imaging (X-ray mammography, MR mammography, chest plain radiography, bone scintigraphy and breast, axillary and liver ultrasonography). The diagnostic accuracies of FDG PET/CT and a conventional algorithm were compared. Diagnostic accuracy was assessed in terms of primary tumour detection rate, correct assessment of primary lesion focality, T stage and the detection rates for lymph node and distant metastases. Histopathology, imaging or clinical follow-up served as the standards of reference.

Results

FDG PET/CT was significantly more accurate for detecting axillary lymph node and distant metastases (p?=?0.0125 and p?Conclusion Full-dose, intravenous contrast-enhanced FDG PET/CT was more accurate than conventional imaging for initial breast cancer staging due to the higher detection rate of metastases and synchronous tumours, although the study had several limitations including a retrospective design, a possible selection bias and a relevant false-positive rate for the detection of axillary lymph node metastases. FDG PET/CT resulted in a change of treatment in a substantial proportion of patients.     

The diagnostic and prognostic value of 18F-FDG PET/CT in the initial assessment of high-grade bone and soft tissue sarcoma. A retrospective study of 89 patients

Purpose

To evaluate the feasibility of ¹⁸F-FDG PET/CT for initial assessment in high-grade bone sarcomas (BS) and soft tissue sarcomas (STS).

Methods

During the years 2001–2010, 89 patients (30 BS, 59 STS) referred for further evaluation and surgical treatment of a high-grade BS or STS also had a PET/CT scan performed for staging preoperatively (n?=?68) or within 1?month of surgery (n?=?21). Metastatic lesions suggested on the PET/CT scan were confirmed or rejected by histological evaluation, by additional imaging or by follow-up. In 68 patients (28 BS, 40 STS) the relationship between the maximal standardized uptake value (SUVmax) of the primary tumour and survival was examined.

Results

The PET/CT scan suggested the presence of 13 metastatic lesions in BS patients (5 lymph node, 8 distant) and 21 metastatic lesions (6 lymph node, 15 distant) in STS patients. The calculated sensitivity (SE) and specificity (SP) were 95?% and 96?% for detection of distant metastases, and the predictive value (PV) of a positive or a negative test was 87?% and 98?%, respectively. SE and SP were 100?% and 90?% for detection of lymph node metastases, and the PV of a positive or a negative test was 27?% and 100?%, respectively. The 5-year survival was 81?% among patients with SUVmax below the median value (≤10), but was 33?% among those with SUVmax >10.

Conclusion

FDG PET/CT for the initial assessment of patients with high-grade BS or STS was feasible with high SE and SP, but in those with lymph node metastases the PV of a positive test was low. The SUVmax of the primary tumour was a strong prognostic factor for survival.     

[18F]fluorocholine PET/CT imaging for the detection of recurrent prostate cancer at PSA relapse: experience in 100 consecutive patients

Purpose We evaluated the potential of PET/CT and [¹⁸F]fluoromethylcholine (FCH) in the assessment of suspected recurrence of prostate cancer after treatment. Methods One hundred consecutive prostate cancer patients with a persistent increase in serum PSA (>0.1 ng/ml) after radical prostatectomy (58 cases), radiotherapy (21 cases) or hormonal therapy alone (21 cases) were investigated. After injection of 3.7–4.07 MBq/kg of FCH, both early (at <15 min) and delayed (at >60 min) PET/CT scans were performed in 43 patients, delayed PET/CT scans in 53 patients and early PET/CT scans in four patients. Results Of the 100 patients, 54 (PSA 0.22–511.79 ng/ml) showed positive FCH PET/CT scans. Thirty-seven patients had bone and/or abdominal lymph node uptake, while 17 showed pelvic activity. Malignant disease was confirmed in all but one. Delayed SUV_max of bone metastases was significantly higher (p<0.0001 by paired t test) than that measured at <15 min, whereas no differences were observed between early and delayed SUVs of malignant lymph nodes or pelvic disease. Forty-six patients (PSA 0.12–14.3 ng/ml) showed negative FCH PET/CT scans. Of the negative PET/CT scans, 89% were obtained in patients with serum PSA <4 ng/ml and 87% in patients with a Gleason score <8. In none of these cases could recurrent tumour be proven clinically during a follow-up of 6 months. Conclusion FCH PET/CT is not likely to have a significant impact on the care of prostate cancer patients with biochemical recurrence until PSA increases to above 4 ng/ml. However, in selected patients, FCH PET/CT helps to exclude distant metastases when salvage local treatment is intended.     

Serum levels of S-100b protein after four years follow-up of patients with melanoma

The early detection of the recurrence and of distant metastases of melanoma can be supported by the detection of S-100 in the serum. In this study we have evaluated the diagnostic significance of the levels of S-100b as a tumor marker in the diagnosis and the follow-up of patients with melanoma. We have studied 27 patients (15 men and 12 women) aged 29-58 years (mean age +/- SD: 46 +/- 11 years) with melanoma in stages I-IV, as shown by histology. The thickness of the tumor was >0.75 mm according to Breslow. Thirty-two healthy individuals 19 men 13 women aged 29-52 years (mean age +/- SD: 44 +/- 9 years) were our control group. Serum samples of S-100b were measured by radioimmunoassay (RIA) every three months during the first and second year, and every six months for the next two years. All patients were operated after the first diagnosis. Our results have shown a cut-off of S-100b values between controls and patients of 0.2 micro g/l. The overall sensitivity and specificity for the diagnosis of melanoma for all stages was 71% and 94% respectively. Patients with recurrence or distant metastases had significantly higher levels of S-100b as compared to those without metastases or recurrence (P<0.05) and to healthy individuals (P<0.05). In 11 patients with elevated serum S-100b levels, after treatment and during the follow up period, these levels were reduced to normal. In conclusion, although the number of our patients was limited, serum S-100b showed after four years of follow up to be useful in stages III and IV of melanoma, in the diagnosis of relapse or metastases and in monitoring the response to treatment.     

Can integrated 18F-FDG PET/MR replace sentinel lymph node resection in malignant melanoma?

Purpose

To compare the sensitivity and specificity of 18F-fluordesoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT), 18F-FDG PET/magnetic resonance (18F-FDG PET/MR) and 18F-FDG PET/MR including diffusion weighted imaging (DWI) in the detection of sentinel lymph node metastases in patients suffering from malignant melanoma.

Material & Methods

Fifty-two patients with malignant melanoma (female: n =?30, male: n =?22, mean age 50.5?±?16.0 years, mean tumor thickness 2.28?±?1.97 mm) who underwent 18F-FDG PET/CT and subsequent PET/MR & DWI for distant metastasis staging were included in this retrospective study. After hybrid imaging, lymphoscintigraphy including single photon emission computed tomography/CT (SPECT/CT) was performed to identify the sentinel lymph node prior to sentinel lymph node biopsy (SLNB). In a total of 87 sentinel lymph nodes in 64 lymph node basins visible on SPECT/CT, 17 lymph node metastases were detected by histopathology. In separate sessions PET/CT, PET/MR, and PET/MR & DWI were assessed for sentinel lymph node metastases by two independent readers. Discrepant results were resolved in a consensus reading. Sensitivities, specificities, positive predictive values and negative predictive values were calculated with histopathology following SPECT/CT guided SLNB as a reference standard.

Results

Compared with histopathology, lymph nodes were true positive in three cases, true negative in 65 cases, false positive in three cases and false negative in 14 cases in PET/CT. PET/MR was true positive in four cases, true negative in 63 cases, false positive in two cases and false negative in 13 cases. Hence, we observed a sensitivity, specificity, positive predictive value and negative predictive value of 17.7, 95.6, 50.0 and 82.3% for PET/CT and 23.5, 96.9, 66.7 and 82.3% for PET/MR. In DWI, 56 sentinel lymph node basins could be analyzed. Here, the additional analysis of DWI led to two additional false positive findings, while the number of true positive findings could not be increased.

Conclusion

In conclusion, integrated 18F-FDG PET/MR does not reliably differentiate N-positive from N-negative melanoma patients. Additional DWI does not increase the sensitivity of 18F-FDG PET/MR. Hence, sentinel lymph node biopsy cannot be replaced by 18F-FDG-PE/MR or 18F-FDG-PET/CT.

     

Superior performance of 18F-fluorocholine digital PET/CT in the detection of parathyroid adenomas

To compare detectability of hyperfunctioning parathyroid tissue (HPT) by digital and analog 18F-fluorocholine PET/CT in patients with primary hyperparathyroidism and negative/inconclusive 99mTc-MIBI scintigraphy-SPECT/CT. Thirty-three patients with primary hyperparathyroidism and negative/inconclusive 99mTc-MIBI scintigraphy-SPECT/CT were prospectively included. All patients accepted to be scanned by digital and analog PET/CT in the same imaging session after a single injection of 18F-fluorocholine. Three nuclear medicine physicians evaluated the digital and analog PET/CT datasets to assess the detection rate of HPT. Maximum standard uptake values (SUVmax) of HPT and locoregional lymph nodes were measured in both systems. HPT was detected in 30/33 patients by the digital system, whereas it was detected in 22/33 patients by the analog system (p < 0.01). Moreover, in 21 of these 33 patients, both systems detected one focal 18F-fluorocholine uptake, and in one patient the digital system detected two foci. Histopathology demonstrated HPT in 32 patients and it was inconclusive in one patient. The digital PET/CT detected HPT in 29 of the 32 patients, and the analog system in 22 of the 32 (p < 0.01). All HPT suspected lesions resected and detected only by the digital system (n = 8) were < 10 mm (7.5 ± 1.3 mm), while those detected by both systems (n = 22) were > 10 mm (13 ± 3.8 mm). SUVmax of HPT lesions was significantly higher than SUVmax of locoregional lymph node independently of the PET/CT system used (4.5 ± 1.9 vs. 2.9 ± 1.3, p < 0.0001). Digital PET/CT offers superior performance over analog system in patients with suspected HPT and previous negative/inconclusive imaging examinations, particularly in sub-centimeter lesions. SUVmax can help in the differentiation between HTP and locoregional lymph nodes.     

Comparison of MRI (including SS SE-EPI and SPIO-enhanced MRI) and FDG-PET/CT for the detection of colorectal liver metastases

Fluoro-18-deoxyglucose positron emission tomography computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI), including unenhanced single-shot spin-echo echo planar imaging (SS SE-EPI) and small paramagnetic iron oxide (SPIO) enhancement, were compared prospectively for detecting colorectal liver metastases. Twenty-four consecutive patients suspected for metastases underwent MRI and FDG-PET/CT. Fourteen patients (58%) had previously received chemotherapy, including seven patients whose chemotherapy was still continuing to within 1 month of the PET/CT study. The mean interval between PET/CT and MRI was 10.2 ± 5.2 days. Histopathology (n = 18) or follow-up imaging (n = 6) were used as reference. Seventy-seven metastases were detected. In nine patients, MRI and PET/CT gave concordant results. Sensitivities for unenhanced SS SE-EPI, MRI without SS SE-EPI and FDG-PET/CT were, respectively, 100% (p = 9 × 10⁻¹⁰ vs PET, p = 8 × 10⁻³ vs MRI without SS SE-EPI), 90% (p = 2 × 10⁻⁷ vs PET) and 60%. PET/CT sensitivity dropped significantly with decreasing size, from 100% in lesions larger than 20 mm (identical to MRI), over 54% in lesions between 10 and 20 mm (p = 3 × 10⁵ versus unenhanced SS SE-EPI), to 32% in lesions under 10 mm (p = 6 × 10⁻⁵ versus unenhanced SS SE-EPI). Positive predictive value of PET was 100% (identical to MRI). MRI, particularly unenhanced SS SE-EPI, has good sensitivity and positive predictive value for detecting liver metastases from colorectal carcinoma. Its sensitivity is better than that of FDG-PET/CT, especially for small lesions.     

Breast cancer staging in a single session: whole-body PET/CT mammography

Our objective was to compare the diagnostic accuracy of an all-in-one protocol of whole-body 18F-FDG PET/CT and integrated 18F-FDG PET/CT mammography with the diagnostic accuracy of a multimodality algorithm for initial breast cancer staging. METHODS: Forty women (mean age, 58.3 y; range, 30.8-78.4 y; SD, 12 y) with suspected breast cancer were included. For the primary tumor, we compared 18F-FDG PET/CT mammography versus MRI mammography; for axillary lymph node status, 18F-FDG PET/CT versus clinical investigation and ultrasound; and for distant metastases, 18F-FDG PET/CT versus a multimodality staging algorithm. Histopathology and clinical follow-up served as the standard of reference. The Fisher exact test evaluated the significance of differences (P < 0.05). Alterations in patient management caused by 18F-FDG PET/CT were documented. RESULTS: No significant differences were found in the detection rate of breast cancer lesions (18F-FDG PET/CT, 95%; MRI, 100%; P = 1). 18F-FDG PET/CT correctly classified lesion focality significantly more often than did MRI (18F-FDG PET/CT, 79%; MRI, 73%; P < 0.001). MRI correctly defined the T stage significantly more often than did 18F-FDG PET/CT (MRI, 77%; 18F-FDG PET/CT, 54%; P = 0.001). 18F-FDG PET/CT detected axillary lymph node metastases in 80% of cases; clinical investigation/ultrasound, in 70%. This difference was not statistically significant (P = 0.067). Distant metastases were detected with 18F-FDG PET/CT in 100% of cases, and the multimodality algorithm identified distant metastases in 70%. This difference was not statistically significant (P = 1). Three patients had extraaxillary lymph node metastases that were detected only by PET/CT (cervical, retroperitoneal, mediastinal/internal mammary group). 18F-FDG PET/CT changed patient management in 12.5% of cases. CONCLUSION: Our data suggest that a whole-body 18F-FDG PET/CT mammography protocol may be used for staging breast cancer in a single session. This initial assessment of the 18F-FDG PET/CT protocol indicates similar accuracy to MRI for the detection of breast cancer lesions. Although MRI seems to be more accurate when assessing the T stage of the tumor, 18F-FDG PET/CT seems able to more accurately define lesion focality. Although 18F-FDG PET/CT mammography was able to detect axillary lymph node metastases with a high sensitivity, this method cannot soon be expected to replace the combination of clinical examination, ultrasound, and sentinel lymph node biopsy for axillary assessment.     

Non-enhanced CT versus contrast-enhanced CT in integrated PET/CT studies for nodal staging of rectal cancer

Purpose The purpose of the present study was to determine the diagnostic accuracy of non-enhanced CT and contrast-enhanced CT in integrated PET/CT studies for preoperative nodal staging of rectal cancer. Methods Retrospective analysis was performed in 53 patients with pathologically proven rectal cancer who had been referred for preoperative staging. All patients underwent integrated PET/CT consisting of non-enhanced and contrast-enhanced CT followed by whole-body fluorine-18-fluorodeoxyglucose ([¹⁸F]FDG) PET. Both non-enhanced and contrast-enhanced PET/CT images were evaluated separately by two observers in consensus. The reference standard was histopathologic results. For nodal staging of rectal cancer, we compared diagnostic accuracy on a per-patient basis between the two modalities. Results Nodal staging was correctly determined with non-enhanced studies in 37 patients (70%) and with contrast-enhanced studies in 42 patients (79%). On a per-patient basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of regional lymph node staging were 85%, 68%, 83%, 72%, and 79%, respectively, with contrast-enhanced studies, and 85%, 42%, 73%, 62%, and 70%, respectively, with non-enhanced studies. The difference in the accuracy of nodal staging between the two modalities was not significant (p = 0.063). Compared with non-enhanced studies, contrast-enhanced studies determined more correctly the status of pararectal lymph nodes (p = 0.002), internal iliac lymph nodes (p = 0.004), and obturator lymph nodes (p < 0.0001). Conclusion Contrast-enhanced PET/CT is superior to non-enhanced PET/CT for precise definition of regional nodal status in rectal cancer.     

Tumour hypoxia imaging with [18F]FAZA PET in head and neck cancer patients: a pilot study

Purpose Hypoxia is an important negative prognostic factor for radiation treatment of head and neck cancer. This study was performed to evaluate the feasibility of use of ¹⁸F-labelled fluoroazomycin arabinoside ([¹⁸F]FAZA) for clinical PET imaging of tumour hypoxia. Methods Eleven patients (age 59.6 ± 9 years) with untreated advanced head and neck cancer were included. After injection of approximately 300 MBq of [¹⁸F]FAZA, a dynamic sequence up to 60 min was acquired on an ECAT HR+ PET scanner. In addition, approximately 2 and 4 h p.i., static whole-body PET (n = 5) or PET/CT (n = 6) imaging was performed. PET data were reconstructed iteratively (OSEM) and fused with CT images (either an external CT or the CT of integrated PET/CT). Standardised uptake values (SUVs) and tumour-to-muscle (T/M) ratios were calculated in tumour and normal tissues. Also, the tumour volume displaying a T/M ratio >1.5 was determined. Results Within the first 60 min of the dynamic sequence, the T/M ratio generally decreased, while generally increasing at later time points. At 2 h p.i., the tumour SUV_max and SUV_mean were found to be 2.3 ± 0.5 (range 1.5–3.4) and 1.4 ± 0.3 (range 1.0–2.1), respectively. The mean T/M ratio at 2 h p.i. was 2.0 ± 0.3 (range 1.6–2.4). The tumour volume displaying a T/M ratio above 1.5 was highly variable. At 2 h p.i., [¹⁸F]FAZA organ distribution was determined as follows: kidney > gallbladder > liver > tumour > muscle > bone > brain > lung. Conclusion [¹⁸F]FAZA PET imaging appears feasible in head and neck cancer patients, and the achieved image quality is adequate for clinical purposes. Based on our initial results, [¹⁸F]FAZA warrants further evaluation as a hypoxia PET tracer for imaging of cancer.     

Whole-body MRI at 1.5 T and 3 T compared with FDG-PET-CT for the detection of tumour recurrence in patients with colorectal cancer

The purpose of this study was to assess the diagnostic accuracy of whole-body MRI (WB-MRI) at 1.5 T or 3 T compared with FDG-PET-CT in the follow-up of patients suffering from colorectal cancer. In a retrospective study, 24 patients with a history of colorectal cancer and suspected tumour recurrence underwent FDG-PET-CT and WB-MRI with the use of parallel imaging (PAT) for follow-up. High resolution coronal T1w-TSE and STIR sequences at four body levels, HASTE imaging of the lungs, contrast-enhanced T1w- and T2w-TSE sequences of the liver, brain, abdomen and pelvis were performed, using WB-MRI at either 1.5 T (n = 14) or 3 T (n = 10). Presence of local recurrent tumour, lymph node involvement and distant metastatic disease was confirmed using radiological follow-up within at least 5 months as a standard of reference. Seventy seven malignant foci in 17 of 24 patients (71%) were detected with both WB-MRI and PET-CT. Both investigations concordantly revealed two local recurrent tumours. PET-CT detected significantly more lymph node metastases (sensitivity 93%, n = 27/29) than WB-MRI (sensitivity 63%, n = 18/29). PET-CT and WB-MRI achieved a similar sensitivity for the detection of organ metastases with 80% and 78%, respectively (37/46 and 36/46). WB-MRI detected brain metastases in one patient. One false-positive local tumour recurrence was indicated by PET-CT. Overall diagnostic accuracy for PET-CT was 91% (sensitivity 86%, specificity 96%) and 83% for WB-MRI (sensitivity 72%, specificity 93%), respectively. Examination time for WB-MRI at 1.5 T and 3 T was 52 min and 43 min, respectively; examination time for PET-CT was 103 min. Initial results suggest that differences in accuracy for local and distant metastases detection using FDG-PET-CT and WB-MRI for integrated screening of tumour recurrence in colorectal cancer depend on the location of the malignant focus. Our results show that nodal disease is better detected using PET-CT, whereas organ disease is depicted equally well by both investigations.     

MRI and hybrid PET/CT for monitoring tumour metastasis in a metastatic breast cancer model in rabbit

OBJECTIVE: To study tumour growth and metastasis in a rabbit metastatic breast cancer (MBC) model and find the most sensitive screening modality in monitoring tumour metastasis. METHODS: The MBC model was established by injecting a VX2 tumour mass suspension into the mammary glands of 23 rabbits and was monitored by using physical examination, X-ray, MRI and hybrid PET/CT. RESULTS: Of all 23 rabbits, axillary lymph node metastasis was detected in 21 (91%) at day 33 after tumour inoculation, mediastinal node metastasis in five (22%) at day 42, abdominal node metastasis in two (9%) at day 48, lung metastasis in six (26%) at day 39, liver metastasis in three (13%) at day 48, and lumbar spine metastasis in one (4%) at day 51. Tumour invasion of pleura was found in one, stomach wall in one, and pleura and stomach concurrently in one rabbit. Sensitivity for detection of lymph node metastases was 78.6% (22/28) and 67.9% (19/28) with MRI and PET/CT, respectively; and sensitivity for detection of metastases in distant organs was 85.7% (12/14) and 71.4% (10/14), respectively. CONCLUSIONS: The MBC model used here exhibits fast tumour growth and extensive metastasis in a relatively short period. Its metastatic pattern is quite similar to that of human MBC and hence could be potentially used as a model for testing imaging modalities and translational research, e.g., MBC management. MRI is superior to PET/CT in monitoring tumour metastasis.     

治疗前胃癌患者18F-FDG PET/CT显像特征分析

目的 探讨治疗前胃癌患者¹⁸F-FDG PET/CT显像特征,并分析影响胃癌原发灶最大标准摄取值(maximum standardized uptake value, SUVmax)的相关因素。方法 选取并分析2017年1月～2019年12月经病理学证实的70例胃癌患者临床资料,所有患者均于治疗前在本院行PET/CT全身显像,显像结果采用半定量分析及视觉分析。不同病理分型、性别、年龄、是否淋巴结转移、是否脏器转移组间原发灶SUVmax值比较采用t检验;不同原发灶部位组间SUVmax值比较采用方差分析;原发灶最大厚度值与原发灶SUVmax值相关性采用Pearson相关分析。结果 70例患者中66例原发灶¹⁸氟-氟代脱氧葡萄糖(¹⁸F-2-fluro-D-deoxy-glucose,¹⁸F-FDG)显像阳性,灵敏度94.3%,SUVmax9.6±4.9;PET显像灵敏度肠型胃癌高于非肠型胃癌[3 3/3 3 (1 0 0%) vs2 7/3 1 (8 7.1%)]、非粘液腺癌高于粘液腺癌[5 4/5 5...     

口腔鳞癌的18F-FDG PET/CT的影像学表现以及与CT平扫的比较研究

目的 评价18F-FDG PET-CT检查在口腔鳞癌患者的诊断和淋巴结转移灶发现的价值.方法 回顾性地分析了18例口腔癌(其中包括16例舌癌和2例口底癌患者)的临床和18F-FDG PET-CT影像学表现及CT平扫的影像学资料.结果 (1)原发病灶的发现全部病例中有5例患者是由PET/CT检查首次发现口腔癌的;PET/CT对原发部位肿瘤病变显示的灵敏度100%(15/15),特异性100%(3/3);CT对原发病灶显示的灵敏度为73.3%(11/15),特异性为66.7%(2/3).(2)18例口腔癌患者中PET/CT诊断颈部淋巴结转移灶共26个,大小介于0.8～1.5 cm之间,标准摄取值(SUV)介于2.5～3.2之间;其中仅有5个淋巴结经病理组织活检证实为淋巴结转移灶.(3)通过PET/CT检查新发现全身其他部位的侵犯和远处转移性病灶8个.结论 PET/CT对口腔鳞癌原发灶诊断的灵敏度和特异性均比CT平扫高;全身PET/CT扫描对舌癌和口底癌的临床分期、术后复发的判定更具价值.