Diagnostic imaging in Merkel cell carcinoma: Lessons to learn from 16 cases with correlation of sonography, CT, MRI and PET

Objective

The authors report imaging findings in a series of 16 patients with MCC, a rare tumour which is often managed primarily by a dermatologist. To our knowledge, no equivalent series of MCC has been described in the nuclear medicine literature.

Material and Methods

In this IRB-approved retrospective noncomparative case series 16 patients with biopsy-proven Merkel cell carcinoma were included between January 1999 and October 2007. Twenty-nine whole body PET scans (18F-FDG n = 24, 18F-FDOPA n = 5) in 16 patients were retrospectively reviewed with regard to tracer uptake in six anatomical sites per patient. For 127/144 of FDG-PET evaluated regions and 68/144 of regions depicted by conventional imaging methods, a valid standard of reference could be obtained. A combined standard of reference was applied, which consisted of histopathology (lymphadenectomy or biopsy) or clinical or radiological follow-up for at least 12 months. Results: the mean FDG uptake over the clinicopatholigical verified FDG avid areas was 4.7 SUV (1.5-9.9 SUV). The region based assessment of diagnostic value, in consideration of the standard of reference, resulted in a sensitivity of 85.7% and a specificity of 96.2% of FDG-PET (n = 127) and in a combined sensitivity of 95.5% and a specificity of 89.1% for morphological imaging methods (n = 68). Differences between methods did not reach statistical significance (p = 1.00, p = 0.18).

Conclusions

FDG-PET is a highly useful whole body staging method of comparable value compared to conventional imaging methods with restricted field of view. The lessons learned from case series are discussed.     

Integrated contrast-enhanced diagnostic whole-body PET/CT as a first-line restaging modality in patients with suspected metastatic recurrence of breast cancer

Objective(s)

Only few information exist about the diagnostic accuracy of PET/CT for restaging patients with metastatic recurrence of breast carcinoma. Therefore, our study hypothesis was to perform diagnostic contrast enhanced CT (ce-CT) and FDG-PET in a one-step investigation, to prove sensitivity of each modality and to determine whether diagnostic PET/CT adds information over PET or contrast enhanced CT alone for restaging of patients with suspected recurrence of breast cancer.

Methods

Fifty-two patients with suspected recurrence of breast cancer were included in our study. All of them were free of metastasis after the first line therapy. Indications for restaging were: Elevated tumor markers n = 32, clinical deterioration n = 16 and/or suspicious findings on other imaging studies n = 48. Integrated PET/CT was performed using contrast-enhanced diagnostic CT for attenuation correction.

Results

PET was correct in 44/52 patients (85%), ce-CT in 38/52 patients (73%) and PET/CT in 50/52 patients (96%). Sensitivity and specificity of lesion detection of PET, CT and PET/CT were 84%, 66% and 93%, and 100%, 92%, and 100%, respectively.

Discussion

PET/CT can improve staging and alter therapeutic options in patients suspected to have breast cancer recurrence and distant metastatic disease, primarily by demonstrating local or distant nodal involvement occult at other imaging studies. The added value of FDG-PET/CT over other diagnostic modalities is mainly expressed by the fact that a noninvasive whole-body evaluation is possible in a single examination.     

Non-small cell carcinoma: Comparison of postoperative intra- and extrathoracic recurrence assessment capability of qualitatively and/or quantitatively assessed FDG-PET/CT and standard radiological examinations

Purpose

The purpose of this study was to compare the capability of integrated FDG-PET/CT for assessment of postoperative intra- and extrathoracic recurrence in non-small cell lung cancer (NSCLC) patients with that of standard radiological examinations.

Materials and methods

A total of 121 consecutive pathologically diagnosed NSCLC patients (80 males, 41 females; mean age, 71 years) underwent pathologically and surgically confirmed complete resection, followed by prospective integrated FDG-PET/CT and standard radiological examinations. Final diagnosis of recurrence was based on the results of more than 12 months of follow-up and/or pathological examinations. The probability of recurrence was assessed with either method for each patient by using 5-point visual scoring system, and final diagnosis was made by consensus between two readers. ROC analysis was used to compare the capability of the two methods for assessment of postoperative recurrence on a per-patient basis. The ROC-based positive test was used to determine optimal cut-off value for FDG uptake measurement at a site suspected on the basis of qualitatively assessed PET/CT. Finally, sensitivities, specificities and accuracies of all methods were compared by means of McNemar's test.

Results

Areas under the curve of qualitatively assessed PET/CT and standard radiological examinations showed no significant differences (p > 0.05). At an optimal cut-off value of 2.5, specificity and accuracy of quantitatively and qualitatively assessed PET/CT were significantly higher than those of qualitatively assessed PET/CT and standard radiological examinations (p < 0.05).

Conclusion

Accuracy of assessment of postoperative intra- and extrathoracic recurrence in NSCLC patients by qualitative and/or quantitative FDG-PET/CT is equivalent to or higher than that by standard radiological examinations.     

“One-stop-shop” staging: Should we prefer FDG-PET/CT or MRI for the detection of bone metastases?

Aim

The aim of this study was to compare the diagnostic accuracy of fully diagnostic, contrast-enhanced whole-body FDG-PET/CT and whole-body MRI for detection of bone metastases in patients suffering from newly diagnosed non-small cell lung cancer and malignant melanoma.

Material and Methods

109 consecutive non-small cell lung cancer (n = 54) and malignant melanoma (n = 55) patients underwent whole-body FDG-PET/CT and whole-body MRI for initial tumor staging. All images were evaluated by four experienced physicians (three radiologists, one nuclear medicine physician). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for detection of bone metastases were determined for both modalities. Statistically significant differences between FDG-PET/CT and MRI were calculated with Fisher's Exact test (p < 0.05). Clinical and imaging follow-up data with a mean follow-up time of 434 days served as the reference standard.

Results

According to the reference standard 11 patients (10%) suffered from bone metastases. The sensitivity, specificity, PPV, NPV, and accuracy for the detection of osseous metastases was 45%, 99%, 83%, 94%, and 94% with whole-body FDG-PET/CT and 64%, 94%, 54%, 96%, and 91% with whole-body MRI. The difference was not statistically significant (p = 0.6147).

Conclusions

FDG-PET/CT and MRI seem to be equally suitable for the detection of skeletal metastases in patients suffering from newly diagnosed non-small cell lung cancer and malignant melanoma. Both modalities go along with a substantial rate of false-negative findings requiring a close follow-up of patients who are staged free of bone metastases at initial staging.     

Thin-section CT of the mediastinum in preoperative N-staging of non-small cell lung cancer: Comparison with FDG PET

Purpose

To compare diagnostic capability of preoperative N-staging of lung cancer between thin-section CT of the mediastinum and FDG PET, and 5 mm slice thickness CT.

Materials and methods

The subjects were 34 patients with lung carcinoma who were examined by both CT and PET, and subsequently underwent surgery between May 2005 and January 2007. CT was carried out with a 16 detector row helical CT scanner. The raw data were reconstructed into 5 mm slice thickness and 1 mm slice thickness (thin-section CT). A total of 251 lymph node stations were retrospectively assessed for the presence of lymph node metastasis with thin-section CT, 5 mm CT and PET. In the interpretations of thin-section CT and 5 mm CT, we employed multi-criteria as follows: nodular calcification and intranodal fat as benign criteria, and short-axis diameter more than 10 mm (size criterion), focal low density other than fat, surrounding fat infiltration and convex margin in hilar lymph nodes, as malignant criteria. On PET, maximum standardized uptake value (SUVmax) of 2.5 or more was used as the criterion of malignancy. Sensitivity and specificity were compared between these examinations using McNemar test.

Results

Sensitivities and specificities of thin-section CT, 5 mm CT and PET were 25%, 25%, 25%, and 97%, 94%, 98%, respectively. The statistical analysis revealed that the specificity of 5 mm CT was significantly lower than those of thin-section CT (p = 0.039) and PET (p = 0.006), while no difference was present between thin-section CT and PET.

Conclusion

Thin-section CT of the mediastinum using multiple criteria was comparable to PET in preoperative N-staging of lung cancer.     

Dynamic magnetic resonance imaging for assessment of minimally invasive pelvic floor reconstruction with polypropylene implant

Introduction

The purpose of the study was to assess the usefulness of dynamic MRI in patients with pelvic organ prolapse after pelvic floor repair with polypropylene mesh.

Materials and methods

Fifteen consecutive patients (mean age 66.5 years) who were scheduled for either anterior (n = 9) or posterior (n = 6) pelvic floor repair were prospectively evaluated by clinical assessment and dynamic MRI 1 day before and 3 months after surgery. MRI diagnoses and MRI measurements of relevant anatomical points at rest and on straining were analysed before and after surgery.

Results

At follow-up assessment 93.3% of all patients were clinically cured. Dynamic MRI showed newly developed (n = 6) or increased (n = 6) pelvic organ prolapse in 80% (n = 12) of all patients 3 months after pelvic floor repair. Most of them (n = 11; 91.7%) affected the untreated pelvic floor compartment. On straining anatomical points of reference in the anterior pelvic floor compartment were significantly (p < 0.05) elevated after anterior repair and rectal bulging was significantly (p = 0.036) reduced after posterior pelvic floor repair.

Conclusions

In this study dynamic MRI could verify the effective support of anterior and posterior pelvic floor structures by anterior and posterior polypropylene implant respectively. But dynamic MRI demonstrates if one compartment of the pelvic floor is repaired another compartment frequently (73.3%) develops dysfunction. These results did not correspond to clinical symptoms on short-term follow-up (3 months). Studies with long-term follow-up are necessary to prove if dynamic MRI can reliably identify clinically significant pelvic organ prolapse after pelvic floor repair before the onset of symptoms.     

Comparison of multidetector CT with F-18-FDG-PET and SPECT in the assessment of myocardial viability in patients with myocardial infarction: a preliminary study

Objective

To evaluate the ability of MDCT to detect a nonviable myocardium in patients with myocardial infarction (MI).

Methods and material

This study included 17 patients with MI in the acute (n = 13) or chronic stage (n = 4). MDCT, SPECT, and F-18-FDG-PET were performed in 10 patients during the acute stage and in 2 during the chronic stage of MI. MDCT and SPECT were performed in 13 patients with acute stage and in 4 with chronic stage of MI. Sixteen-slice MDCT was performed 10 min after injection of 120 mL of nonionic contrast media. MDCT, SPECT and PET images were analyzed using a 17-segment model. The depth of hyperenhancement >2/3 was defined as nonviable at MDCT.

Results

MDCT and SPECT were concordant in localizing the MI in 84.2% (272/323 segments) and were discordant in 15.8% (51/323). MDCT and PET were concordant in localizing MI in 89.2% (182/204) and discordant in 10.8% (22/204). The sensitivity, specificity and diagnostic accuracy of MDCT in determining the nonviable segments were 70.4%, 85.3%, 81.4% as compared with PET, respectively, and 69.4%, 81.8%, 79.9% compared with SPECT, respectively, and 73.5%, 79.4%, 78.4% compared with combined PET and SPECT, respectively. MDCT findings suggested nonviability in additional 16 segments (5.0%) and 7 segments (3.4%) where MI was not detected on SPECT and FDG-PET, respectively.

Conclusion

MDCT is useful for determining myocardial viability in patients with myocardial infarction and more sensitive than SPECT and FDG-PET in detecting a nonviable myocardium.     

Dual-energy CT angiography of chronic thromboembolic disease: Can it help recognize links between the severity of pulmonary arterial obstruction and perfusion defects?

Purpose

To evaluate whether dual-energy CT angiography (DE-CTA) could identify links between morphologic and functional abnormalities in chronic pulmonary thromboembolism (CPTE).

Materials and methods

Seventeen consecutive patients with CPTE without underlying cardio-respiratory disease were investigated with DE-CTA. Two series of images were generated: (a) transverse diagnostic scans (i.e., contiguous 1-mm thick averaged images from both tubes), and (b) perfusion scans (i.e., images of the iodine content within the microcirculation; 4-mm thick MIPs). Two radiologists evaluated by consensus the presence of: (a) pulmonary vascular features of CPTE and abnormally dilated systemic arteries on diagnostic CT scans, and (b) perfusion defects of embolic type on perfusion scans.

Results

Diagnostic examinations showed a total of 166 pulmonary arteries (166/833; 19.9%) with features of CPTE, more frequent at the level of peripheral than central arteries (8.94 vs 0.82; p < 0.0001), including severe stenosis with partial (97/166; 58.4%) or complete (20/166; 12.0%) obstruction, webs and bands (37/166; 22.3%), partial filling defects without stenosis (7/166; 4.2%), focal stenosis (4/166; 2.4%) and abrupt vessel narrowing (1/166; 0.6%). Perfusion examinations showed 39 perfusion defects in 8 patients (median number: 4.9; range: 1-11). The most severe pulmonary arterial features of CPTE were seen with a significantly higher frequency in segments with perfusion defects than in segments with normal perfusion (p < 0.0001). Enlarged systemic arteries were observed with a significantly higher frequency ipsilateral to lungs with perfusion defects (9/12; 75%) compared with lungs without perfusion defects (5/22; 22.7%) (p = 0.004).

Conclusion

Dual-energy CTA demonstrates links between the severity of pulmonary arterial obstruction and perfusion impairment, influenced by the degree of development of the systemic collateral supply.     

Integrated FDG-PET/CT vs. standard radiological examinations: Comparison of capability for assessment of postoperative recurrence in non-small cell lung cancer patients

Purpose

The purpose of this study was to prospectively and directly compare diagnostic capabilities of whole-body integrated FDG-PET/CT and standard radiologic examination for assessment of recurrence in postoperative non-small cell lung cancer (NSCLC) patients.

Materials and methods

A total of 92 consecutive pathologically diagnosed NSCLC patients (65 males, 27 females; mean age, 71 years) underwent pathologically and surgically proven complete resection, followed by prospective whole-body FDG-PET/CT and standard radiological examinations. Final diagnosis of recurrence was based on the results of more than 1 year of follow-up and/or pathological examinations. On both methods, the probability of recurrence was assessed in each patient by using a five-point visual scoring system, and the each final diagnosis was made by consensus between two readers. Kappa analyses were performed to determine inter-observer agreement for both methods, and ROC analyses were used to compare capability of the two methods for assessment of postoperative recurrence on a per-patient basis. Sensitivity, specificity and accuracy were also compared between PET/CT and standard radiological examination by means of McNemar's test.

Results

All inter-observer agreements were almost perfect (integrated PET/CT: κ = 0.89; standard radiological examination: κ = 0.81). There were no statistically significant differences in area under the curve, sensitivity, specificity and accuracy between integrated FDG-PET/CT and standard radiologic examinations (p > 0.05).

Conclusion

Integrated FDG-PET/CT can be used for assessment of postoperative recurrence in NSCLC patients with accuracy as good as that of standard radiological examinations.     

Dual-time point scanning of integrated FDG PET/CT for the evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT

Purpose

To evaluate whether dual-time point scanning with integrated fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography and computed tomography (PET/CT) is useful for evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT.

Materials and methods

PET/CT data and pathological findings of 560 nodal stations in 129 patients with pathologically proven non-small cell lung cancer diagnosed as operable by contrast-enhanced CT were reviewed retrospectively. Standardized uptake values (SUVs) on early scans (SUVe) 1 h, and on delayed scans (SUVd) 2 h after FDG injection of each nodal station were measured. Retention index (RI) (%) was calculated by subtracting SUVe from SUVd and dividing by SUVe. Logistic regression analysis was performed with seven kinds of models, consisting of (1) SUVe, (2) SUVd, (3) RI, (4) SUVe and SUVd, (5) SUVe and RI, (6) SUVd and RI, and (7) SUVe, SUVd and RI. The seven derived models were compared by receiver-operating characteristic (ROC) analysis. k-Fold cross-validation was performed with k values of 5 and 10. p < 0.05 was considered statistically significant.

Results

Model (1) including the term of SUVe showed the largest area under the ROC curve among the seven models. The cut-off probability of metastasis of 3.5% with SUVe of 2.5 revealed a sensitivity of 78% and a specificity of 81% on ROC analysis, and approximately 60% and 80% on k-fold cross-validation.

Conclusion

Single scanning of PET/CT is sufficiently useful for evaluating mediastinal and hilar nodes for metastasis.     

Positive enteric contrast material for abdominal and pelvic CT with automatic exposure control: what is the effect on patient radiation exposure?

Objective

To assess the effect of positive enteric contrast administration on automatic exposure control (AEC) CT radiation exposure in (1) a CT phantom, and (2) a retrospective review of patients.

Materials and methods

We scanned a CT phantom containing simulated bowel that was sequentially filled with water and positive enteric contrast, and recorded the mean volume CT dose index (CTDIvol). We also identified 17 patients who had undergone 2 technically comparable CT scans of the abdomen and pelvis, one with positive enteric contrast and the other with oral water. Paired Student's t-tests were used to compare the mean CTDIvol between scans performed with and without positive enteric contrast. Both the phantom and patient CT scans were performed using AEC with a fixed noise index.

Results

The mean CTDIvol for the phantom with simulated bowel containing water and positive enteric contrast were 8.2 ± 0.2 mGy, and 8.7 ± 0.1 mGy (6.1% higher than water, p = 0.02), respectively. The mean CTDIvol for patients scanned with oral water and with positive enteric contrast were 11.8 mGy and 13.1 mGy, respectively (p = 0.003). This corresponded to a mean CTDIvol which was 11.0% higher (range: 0.0-20.7% higher) in scans with positive enteric contrast than those with oral water in patients.

Conclusions

When automatic exposure control is utilized for abdominopelvic CT, the radiation exposure, as measured by CTDIvol, is higher for scans performed with positive enteric contrast than those with oral water.     

Respiratory gated multidetector computed tomography: Applicable for diagnostic abdominal imaging?

Purpose

To evaluate the ability and accuracy of a respiratory gated technique used with contrast enhanced MDCT of the upper abdomen with focus on diagnostic image quality and depiction of organs and major vessels.

Materials and methods

Forty-five adult patients who were referred to our institution for follow-up dynamic contrast enhanced abdominal CT imaging were included in this study. Respiratory gated CT scans were performed with the use of a dedicated hardware. A multiphasic CT scan was performed for each patient. Respiratory gated images were obtained between early arterial and portal venous phases during free breathing. Images of respiratory gated (RG) and breathhold (BH) phases were compared qualitatively and quantitatively by two radiologists. Definitive statistical methods were used for evaluating the scoring data, while Mann Whitney U test was used for comparison. Statistical significance was accepted for p values <0.05.

Results

Statistical significant difference was found for comparison of scores regarding luminal opacification and contoural integrity of intrahepatic vascular structures with scores of RG scans rated poor to moderate (e.g. 2.86 ± 1.07 for luminal opacification of intrahepatic portal veins as well as border detectability) in comparison to scores of BH scans rated good to excellent (e.g. 1.37 ± 1.31 for luminal opacification, 1.35 ± 1.28 for border detectability of intrahepatic portal veins, p < 0.001). Furthermore, statistical significant differences were found for general image noise levels (p < 0.001).

Conclusions

Further technical advances of RG technique could enable routine use of this technique for selected patient groups.     

Previous imaging findings of breast cancers that occurred in combined screening negatives

Purpose

To retrospectively evaluate previous imaging findings of breast cancers that occurred in women whose combined screening using both mammography and ultrasonography was negative.

Materials and methods

A search of the institutional database identified 65 patients with breast cancers who had comparable previous negative screening mammography and ultrasonography (BI-RADS category 1 or 2) within 2 years. We classified each case as true or false negative. The previous imaging findings and the final outcome were analyzed.

Results

Among 65 cases, 42 (65%) were true negatives, 23 (35%) were false negatives. The abnormalities of false negatives were underestimated in 16 (70%) and unrecognized in 7 (30%). The findings were calcifications (n = 8) or a mass (n = 6) on mammography, a mass (n = 5) or a non-mass (n = 3) on ultrasonography and a density on mammography correlated with non-mass on ultrasonography (n = 1). Ductal carcinoma in situ among false and true negatives accounted for 5 (22%) and 7 (17%), respectively. Symptomatic cancers among false and true negatives were 6 (26%) and 13 (31%), respectively.

Conclusion

Breast cancers that rarely occurred in combined screening negatives are often retrospectively seen as minimal abnormalities on previous imaging studies.     

CT characteristics of resolving ground-glass opacities in a lung cancer screening programme

Purpose

This study aimed at evaluating the computed tomography (CT) characteristics of resolving localized ground-glass opacities (GGOs) in a screening programme for lung cancer.

Material and methods

280 patients at high-risk for lung cancer (221 men, 59 women; mean age, 58.6 years), divided into four groups (lung cancer history (n = 83), head and neck cancer history (n = 63), symptomatic (n = 88) and asymptomatic (n = 46) cigarette smokers), were included in a prospective trial with annual low-dose CT for lung cancer screening. We retrospectively reviewed all localized GGOs, analyzed the CT characteristics on initial CT scans and changes during follow-up (median 29.1 months). Variables associated with resolution of GGOs were tested using chi-square or Mann-Whitney tests.

Results

A total of 75 GGOs were detected in 37 patients; 54.7% were present at baseline and 45.3% appeared on annual CT. During follow-up, 56.2% persisted and 43.8% disappeared. The resolving localized GGOs were significantly more often lobular GGOs (p = 0.006), polygonal in shape (p = 0.02), mixed (p = 0.003) and larger (p < 0.0001) than non-resolving localized GGOs.

Conclusion

Localized GGOs are frequent and many disappeared on follow-up. CT characteristics of resolving GGOs show significant differences compared to persistent ones. This study emphasizes the importance of short-term CT follow-up in subjects with localized GGOs.     

The value of PET/CT for preoperative staging of advanced gastric cancer: Comparison with contrast-enhanced CT

Aim

To date, no data are available on the use of PET/CT for preoperative staging of gastric cancer. We attempted to evaluate the value of PET/CT for preoperative staging of advanced gastric cancer, and to compare the use of PET/CT with contrast-enhanced CT (CECT).

Materials and methods

We analyzed PET/CT of 78 patients with surgically proven advanced gastric cancer who had undergone preoperative CECT. Qualitative analysis was conducted by assessing the presence of primary tumors and metastases with PET/CT and CECT.

Results

Among 71 patients who underwent a gastrectomy, 69 primary tumors (93%) were diagnosed by PET/CT, while 64 primary tumors (90%) were detected by CECT (p = 0.55). For regional lymph node metastasis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT vs. CECT were 41% vs. 25% (p = 0.00019), 100% vs. 92% (p = 0.31), 100% vs. 98% (p = 0.46), 26% vs. 42% (p = 0.14), and 51% vs. 72% (p = 0.00089), respectively.

Conclusion

Overall, PET/CT showed comparable diagnostic performance to CECT in diagnosing primary tumors and regional lymph node metastases, though PET/CT was inferior to CECT for the sensitivity and accuracy in diagnosing regional lymph node metastases. Nevertheless, PET/CT would be useful when CECT findings were equivocal due to its high positive predictability.     

Jugular versus subclavian totally implantable access ports: Catheter position, complications and intrainterventional pain perception

Purpose

To determine the safest and most tolerable method for totally implantable access ports (TIAPs) particularly in regard to patient's pain perception and catheter-related complications.

Materials and methods

From January 2007 to October 2008 a subcutaneous TIAP (Bardport, Bard Access System, UT, USA) was implanted in 138 oncological patients (60 male, 78 female; 18-85 years old; mean age of 56 ± 6 years) by experienced interventional radiologists. 94 TIAP were implanted through the subclavian vein (subclavian group) and 44 TIAP were implanted through the internal jugular vein (jugular group). Intrainterventional pain perception (visual analogue scale from 1 to 10), postinterventional catheter tip migration and radiation dose were documented for each method and implantation side and differences were compared with Wilcoxon t-test. For ordinal variables, comparison of two groups was performed with the Fisher's exact test.

Results

No severe periinterventional complication occurred. Inadvertent arterial punctures without serious consequences were reported in one case for the jugular group versus four cases in the subclavian group. Significantly (p < 0.05) lower pain perception, radiation dose and tip migration rate were observed in the jugular group. Catheter occlusions occurred in 4% (n = 4) of the subclavian group versus 2% (n = 1) of the jugular group. The corresponding values for vein thrombosis and catheter dislocation were 3% (n = 3) and 1% (n = 1) in the subclavian group, while none of those complications occurred in the jugular group.

Conclusion

Both techniques, the TIAP implantation via fluoroscopy-guided subclavian vein puncture and via ultrasound-guided jugular vein puncture, are feasible and safe. Regarding intrainterventional pain perception, radiation dose, postinterventional catheter tip position and port function the jugular vein puncture under ultrasound guidance seems to be advantageous.     

FDG-PET/CT in advanced ovarian cancer staging: Value and pitfalls in detecting lesions in different abdominal and pelvic quadrants compared with laparoscopy

Introduction and aim

Ovarian carcinoma (OC) is a common cancer in the Western Countries, and an important cause of death in patients suffering with gynaecologic malignancies. The majority of patients present with advanced disease at the time of diagnosis. Treatment with debulking surgery followed by chemotherapy is the standard approach while chemotherapy is contemplated when surgery is not possible. A correct pre-operative staging is important to ensure a most appropriate management. Laparoscopy (LPS) is the standard diagnostic tool for the assessment of intraperitoneal infiltration but is invasive and requires general anaesthesia. FDG-PET/CT is increasingly used for staging different types of cancer, and the aim of this study is to assess the value of FDG-PET/CT in staging advanced OC and its sensitivity to detect lesions in different quadrants of the abdominal-pelvic area compared to laparoscopy.

Materials and methods

From September 2004 till April 2008, 40 patients with high suspicion of OC were referred to our hospital for diagnostic LPS to explore the possibility of optimal debulking surgery. Those who were not suitable for surgery were referred for chemotherapy. Before chemotherapy, the patients underwent an FDG-PET/CT scan. The findings in 9 quadrants of abdominal-pelvic area (total 360 quadrants) for PET/CT and LPS were recorded and compared.

Results

In 14/360 areas (3.8%), surgical evaluation was not possible because of presence of adhesions, thus the number of areas explored by laparoscopy was 346. Tumour was found in 308 quadrants (38 quadrants free of disease). PET/CT was positive in all 40 patients with true negative results in 26/346 quadrants (7.5%), and true positives results in 243/346 quadrants (70.2%). False positive and negative PET/CT results were found in 12/346 and 65/346 quadrants, respectively. False positive PET/CT findings were evenly present in all quadrants. False negative PET/CT findings were present in 31/109 (28.4%) upper abdominal quadrants (epigastrium and diaphragmatic areas). Final analysis showed a sensitivity and specificity for PET/TC of 78.9 and 68.4% respectively with a positive predictive value of 95.3%. A significant difference was noted between mean SUVmax associated with lesions smaller or larger than 0.5 cm (p = 0.006).

Conclusion

Our results suggest that PET/CT may prove a useful tool for pre-surgical staging of ovarian cancer with a sensitivity and specificity of 78 and 68%, respectively. However, it may be used in combination with laparoscopy for better results. PET/CT showed an adequate correlation between SUVmax values and laparoscopy findings of lesions >5 mm, but a high rate of false negative results in lesions <5 mm such as in carcinomatosis. PET/CT should be used carefully in early stage disease, with low risk of peritoneal infiltration, because of high rate of false positive results, to avoid unnecessary therapy procedures.     

Role of FDG-PET and PET/CT in the diagnosis and management of vasculitis

Purpose

to investigate the role of FDG-PET and PET/CT in the evaluation of vasculitis.

Materials and methods

a systematic revision of the papers published in PubMed/Medline until December 2009 was done.

Results

FDG-PET and PET/CT have been proven to be valuable in the diagnosis of large-vessel vasculitis, especially giant cells arteritis with sensitivity values ranging 77% to 92%, and specificity values ranging 89% to 100%. In particular, FDG-PET/CT has demonstrated the potential to non-invasively diagnose the onset of the vasculitis earlier than traditional anatomical imaging techniques, thus enabling prompt treatment. False positive results mainly occur in the differential diagnosis between vasculitis and atherosclerotic vessels in elderly patients. Another area where FDG-PET/CT is gaining wider acceptance is in monitoring response to therapy; it can reliably detect the earliest changes of disease improvement post-therapy, and persistent activity is an indicator of non-responders to therapy. A few data have been reported about medium/small vessel vasculitis.

Discussion

FDG-PET and PET/CT have proven utility: (a) in the initial diagnosis of patients suspected of having vasculitis particularly in those who present with non-specific symptoms; (b) in the identification of areas of increased FDG uptake in which a biopsy should be done for obtaining a diagnosis; (c) in evaluating the extent of the disease; (d) in assessing response to treatment.     

Bioevaluation study of P-CP-PLLA particle brachytherapy in a rabbit VX2 lung tumor model

Objective

The purpose of this study was to investigate the therapy effects of intratumoral administration of ³²P-CP-PLLA particles in a rabbit VX2 lung tumor model.

Methods

16 rabbits with tumors were randomly divided into 4 groups. 4 rabbits served as untreated controls, and others received intratumoral administration of ³²P-CP-PLLA particles with CT guidance. The total radioactivities in treated groups were as follows: a low activity was 93 MBq (n=4) (group 1), a medium activity was 185 MBq (n=4) (group 2) and a high activity was 370 MBq (n=4) (group 3). Brachytherapy treated VX2 tumors underwent ¹⁸F-FDG PET/CT at 0 day, 3 day, 7 day and 14 day postinjection. In control group, ¹⁸F-FDG PET/CT images were acquired at the same time points but without any treatment. Bremsstrahlung SPECT images were performed at 14 days after intratumoral brachytherapy in treated groups. After Bremsstrahlung SPECT and last ¹⁸F-FDG PET/CT imagings, the rabbits were euthanized and the tumors were removed for histological examination.

Results

Bremsstrahlung SPECT images study indicated that there was no leakage of ³²P out of the injection site at 14 days after treatment. Compared with the control, the tumor volumes in treated groups significantly decreased, and ³²P-CP-PLLA particle produced a reduction in maximum or mean SUV of VX2 tumor (p<0.05). The percentage changes in maximum and mean SUV gradually decreased in group 1 and group 2 from day 3 to day 14 (p<0.05). A transient increase in ¹⁸F-FDG accumulation at group 3 occurred due to the inflammatory reaction elements. Activity dependence was seen in HE and PCNA staining after 14 days treatment among three treated groups (p<0.05).

Conclusions

Our data suggested that ³²P-CP-PLLA particle localized on the injecting sites. This novel brachytherapy device efficiently suppressed the growth of the VX2 tumors implanted in the rabbit.