Importance of combined use of preoperative 18F-FDG PET/CT imaging and intraoperative 18F-FDG handheld gamma probe detection in recurrent papillary thyroid cancer.

Radio-guided surgery using an intra-operative positron emission tomography (PET) probe in recurrent thyroid cancer (RTC) can be a useful method for tumor localization, verification of complete excision and to decrease operation time. We describe a case of RTC whose serum thyroglobulin (Tg) level was 5.6ng/mL. Preoperative fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) revealed two focal abnormalities in the anterior tracheal and right upper mediastinal regions and a handheld gamma probe was used intraoperatively to identify the hot areas seen on PET scan. Postoperative 18F-FDG PET/CT imaging after tumor excision was normal. This case shows that recurrent tumor can be localized correctly using 18F-FDG PET/CT and a surgical gamma probe.

Comparison of (18)F-fluorodeoxyglucose PET/CT findings with vascular endothelial growth factors and receptors in colorectal cancer.

The purpose of this study was to evaluate the association of (18)F-fluorodeoxyglucose (FDG)-PET/CT findings with the vascular endothelial growth factor (VEGF) family and its receptor (VEGFR) levels in metastatic and nonmetastatic colorectal cancer (CRC). Fluorine-18 FDG-PET/CT scans were performed for initial staging and restaging of patients with CRC. FDG-PET/CT findings of tumor (such as the presence of a primary tumor, the lymphatic or distance metastases, and the maximum standardized uptake value (SUVmax) of the primary tumor), serum VEGF A-C-D-E levels, and serum VEGF receptor 1-2-3 levels were analyzed. A total of 63 patients were included into the study (35 males, mean age 61.3 ± 11.9 years). Patients were divided into two groups, based on positive and negative PET/CT findings. Patients were also categorized according to the presence of metastasis. All evaluated parameters were significantly higher in the PET/CT-positive group than the PET/CT-negative group (p < 0.001). All those parameters were also positively correlated with each other. The highest correlation for SUVmax of primary tumor was found with VEGFR-3 (p < 0.001, r = 0.665). Patients with metastases had high levels of VEGF-D, VEGF-A, VEGF-C, VEGF-E, and VEGFR-3 than those without metastases. These parameters had better specificity and sensitivity values than the SUVmax of the primary tumor for detection of metastases. However, VEGF-D was the best indicator of metastasis in all of those parameters (VEGF-D vs SUVmax; sensitivity 100 vs 100 %; specificity 76 vs 76 %; AUC 0.903 vs 0.835; p < 0.001, respectively). Vascular endothelial growth factor family and its receptors were significantly higher in metastatic CRC patients. VEGF-D was the best indicator of metastasis than all VEGF family, VEGFR-3, and primary tumor SUVmax. VEGF family (A-C-D-E) and VEGFR-3 may help to determine the prognosis and management of CRC.

FDG and FDG-labelled leucocyte PET/CT in the imaging of prosthetic joint infection.

PURPOSE: The demand for arthroplasty is rapidly growing as a result of the ageing of the population. Although complications such as heterotrophic ossification, fracture and dislocation are relatively rare, differentiating aseptic loosening, the most common complication of arthroplasty from infection, is a major challenge for clinicians. Radionuclide imaging is currently the imaging modality of choice since it is not affected by orthopaedic hardware. Whereas FDG PET/CT imaging has been widely used in periprosthetic infection, it cannot discriminate aseptic from septic inflammation. In this study we aimed to evaluate the role of FDG PET/CT and FDG-labelled leucocyte PET/CT in the diagnosis of periprosthetic infection. METHODS: Of 54 patients with painful joint arthroplasty who were imaged by FDG PET/CT for diagnosis of periprosthetic infection examined, 46 (36 women, 10 men; mean age 61.04 ± 12.2 years, range 32-89 years) with 54 painful joint prostheses (19 hip, 35 knee) with grade 2 (above liver uptake) FDG accumulation on FDG PET/CT were included in the study and these 46 patients also underwent FDG-labelled leucocyte PET/CT. Final diagnoses were made by histopathological-microbiological culture or clinical follow-up. RESULTS: The final diagnosis showed infection in 15 (28%) and aseptic loosening in 39 (72%) of the 54 prostheses. FDG PET/CT was found to have a positive predictive value of 28% (15/54). Since patients with no FDG uptake on FDG PET/CT were excluded from the study, the sensitivity, specificity, negative predictive value and accuracy could not be calculated. The sensitivity, specificity, and positive and negative predictive values of FDG-labelled leucocyte PET/CT were 93.3% (14/15), 97.4% (38/39), 93.3% and 97.4%, respectively. CONCLUSION: Since FDG is not specific to infection, the specificity of FDG PET/CT was very low. FDG-labelled leucocyte PET/CT with its high specificity may be a useful method and better than labelled leucocyte scintigraphy in periprosthetic infection imaging.

Excision of axillary lymph node recurrences in breast cancer patients with axillary ROLL (A-ROLL).

BACKGROUND AND OBJECTIVES: Conventional surgical exploration to find clinically occult axillary lymph node recurrence of breast cancer can be challenging. The aim of this study was to determine the place of our alternative technique, axillary-ROLL (A-ROLL), in previously treated breast cancer patients with nonpalpable axillary lymph node recurrences. METHODS: Between March 2005 and May 2009, included in this retrospective study were four women (age, 42-51 years) without clinical evidence of distant metastasis who had treatment for breast cancer and were subsequently found to have suspicious axillary lymph node(s) detected by control ultrasonography (US) examination during follow-up. A-ROLL was utilized for the identification of lymph nodes. 0.5-1 mCi (99m)Tc-human serum albumin makroaggregate was injected under US guidance. A gamma probe was then used to guide the excision of the lymph nodes. RESULTS: The involved lymph nodes were successfully localized by A-ROLL technique and removed surgically. Of all four patients, postoperative histopathologic examination revealed nodal cancer metastases in three patients (75%) and lymphoid hyperplasia in one patient. No complications occurred. CONCLUSIONS: A-ROLL technique has proved to be accurate and safe in the identification and excision of clinically occult axillary lymph node recurrence.

The value of different washout parameters in the evaluation of renal transplants by technetium-99m-ethylene- l-l-dicysteine.

Technetium-99m-ethylene-l-l-dicysteine ((99m)Tc-EC) is an agent with a potential for renal imaging. It is reported that EC uses the same tubular transporter system as ortho-hippurate (OIH) and mercaptoacetyltriglycine (MAG3) and that this agent has good imaging properties and higher renal clearance than MAG3. In this study we used (99m)Tc-EC to compare different washout parameters in renal transplanted patients. Sixty nine scans in 55 patients (38 males, 17 females) were performed with (99m)Tc-EC during the follow-up period after kidney transplantation. After bolus injection of 280MBq (99m)Tc-EC, 60x1sec and 29x1min images were taken in anterior position. Perfusions of transplanted kidneys were examined visually and perfusion indices (PI) were calculated according to Hilson's method. The semiquantitative washout parameters such as 20 and 30min to peak activity ratios and 20 and 30min to 3min activity ratios were calculated. The patients were clinically evaluated by nephrologists experienced in renal transplantation cases and followed-up by serum creatinine and blood urea nitrogen determinants which were checked every postoperative day until stabilized to a optimal level for each patient. Two standard deviations above the mean values derived from all cases with normal functioning transplanted kidneys were calculated for each method. Then, these values served as the threshold to differentiate the pathological cases respectively. Of the 69 total studies performed, we found 34 normal kidneys, 14 rejections, 19 acute tubular necrosis (ATN) and 2 cyclosporin A toxicity cases. The number of abnormal cases detected with 30/3min, 30/max, 20/3min and 20/max indices were 27, 26, 24, and 18, respectively. In conclusion, we strongly recommend in studying renal transplants to consider the activity at the 3(rd) min post injection as a reference point instead of the time to maximum activity for washout index calculation. If, for any reason the time to maximum counts using (99m)Tc-(peak activity) is prefered, then the period of study should not be performed for less than 30min to achieve reliable results.

Diagnostic value of magnetic resonance imaging and scintigraphy in patients with metastatic breast cancer of the axial skeleton: a comparative study.

PURPOSE: The goal of this study was to compare the sensitivity of MRI and scintigraphy for detecting metastatic bone disease involving the axial skeleton. PATIENTS AND METHODS: A total of 59 patients (58 women and 1 man, age range 28-83 years, mean age 53.0 years) with histopathologically proven breast cancer during a 15-month period (between April 2003 and January 2004) were included in the study. All the patients underwent scintigraphy and MRI examinations for staging, follow-up, or evaluation of bone pain. RESULTS: MR imaging revealed 59 metastases in 59 patients (sensitivity, 95%; specificity, 100%; positive predictive value, 100%). Four lesions detected by MRI were classified as of uncertain origin (grade 2) and 36 lesions were regarded as definitely benign (grade 1). Scintigraphy revealed 44 metastases in 59 patients (sensitivity, 70%; specificity, 94%; positive predictive value, 95%). A total of 29 lesions were considered as of uncertain origin (grade 2), and 26 lesions were regarded as definitely benign (grade 1). About five lesions were graded as grade 2 in scintigraphy, while MRI graded them as degeneration or benign compression (Grade 1). For 11 lesions the same grade was regarded in both MRI and scintigraphy. Two lesions graded as grade 3, and eleven lesions graded as grade 2 in scintigraphy demonstrated no pathological signal intensity in MRI. In total, 18 lesions with no activity in scintigraphy were graded as grade 3 lesions in MRI. CONCLUSION: MRI is more sensitive than scintigraphy in the detection of bone metastases. MRI appears to be able to screen patients more effectively than scintigraphy if the spine and pelvis are included because metastases merely outside the axial skeleton are rare.

FDG PET/CT findings in recurrent malignant schwannoma.

Malignant schwannoma is an uncommon but aggressive sarcoma that most commonly arises in young and middle-aged adults. We present a 28-year-old male patient with a recurrent chest wall malignant schwannoma. An FDG PET/CT was performed to evaluate the management of the patient. The PET/CT images showed hypermetabolic mass lesions in the left upper chest wall and increased FDG uptake in the left axillary region. The pathologic results confirmed the PET findings. We conclude that FDG PET/CT could play an important role in the staging, restaging, and post-therapy follow-up of malignant schwannomas.

Female breast surface radiation exposure during FDG PET/CT examinations.

BACKGROUND: The combined positron emission tomography (PET) and computed tomography (CT) scanners have been developed in which CT data can be used for both anatomical landmarks and attenuation correction of PET images. However, this modality potentially introduces more radiation burden to patients compared to conventional PET scanning as a result of the added radiation exposure received from CT examination. The purpose of our study was to determine the breast radiation doses of combined PET/CT examination. MATERIAL AND METHODS: Patients' superficial breast doses were calculated using thermoluminescence dosimeters (TLDs) placed onto the surface of the breasts. TLDs were positioned before FDG injection and removed after 24 h. We also determined the average superficial and glandular breast radiation doses from the anthropomorphic dosimetric phantom imaged using similar CT protocol (low dose) to the patients' study. RESULTS: The mean superficial breast dose of the breast skin measured from the PET/CT studies was 14.42+/-2.41 mGy. The average superficial and glandular breast doses of the anthropomorphic phantom measured from the low-dose CT was 9.50 mGy and 5.94 mGy, respectively. CONCLUSION: This study showed that radiation exposure to the breasts during PET/CT was higher than the recommended doses. Therefore, combined PET/CT scanning must be used for essential indications, particularly in women of reproductive age and preferentially a low-dose CT protocol should be implemented to avoid overexposure in such patients.

The additional value of FDG PET imaging for distinguishing N0 or N1 from N2 stage in preoperative staging of non-small cell lung cancer in region where the prevalence of inflammatory lung disease is high.

PURPOSE: The aim of this study was to evaluate the efficacy of PET imaging and compare it with the performance of CT in mediastinal and hilar lymph node staging in potentially operable non-small cell lung cancer (NSCLC). METHODS: Fifty-nine patients with potentially resectable NSCLC who underwent preoperative PET and CT imaging were enrolled into this prospective study. All patients underwent surgical evaluation by means of mediastinoscopy with mediastinal lymph node sampling (14 patients) or thoracotomy (45 patients). RESULTS: The prevalence of lymph node metastases was 53%. Overall, the sensitivity, specificity, accuracy, PPV, and NPV of PET were 79%, 76%, 78%, 86%, and 76% for N0 and N1 lymph nodes and 76%, 79%, 80%, 67%, and 83% for N2 lymph nodes, while those values for CT were 66%, 43%, 58%, 68%, and 43% for N0 and N1 stations and 43%, 66%, 54%, 41%, and 66% for N2 lymph nodes, respectively. PET correctly differentiated cases with mediastinal lymph node involvement (N2) from those without such involvement (N0 or N1) in 76% of cases. Statistical analysis of the diagnostic accuracy of nodal involvement showed that PET improves diagnostic accuracy significantly in the detection of both N0 or N1 and N2 status in the individual patient based on analysis, compared with CT (P < 0.01 and P < 0.01, respectively). When preoperative nodal staging was compared with postoperative histopathological staging, 38 (65%) patients were correctly staged, 9 (15%) were overstaged, and 12 (20%) were understaged by PET, while 29 patients (49%) were correctly staged, 13 (22%) were overstaged, and 17 (29%) were understaged by CT. CONCLUSION: It has been clearly shown that PET is more accurate than CT for the differentiation of N0 or N1 from N2 disease in patients with NSCLC. However, PET imaging alone does not appear to be sufficient to replace mediastinoscopy for mediastinal staging in patients with lung cancer, especially in geographic regions with high granulomatous or inflammatory mediastinal disease prevalence.

Avoidance of misinterpretation of an FDG positive sacral insufficiency fracture using PET/CT scans in a patient with endometrial cancer: a case report.

Whole-body FDG PET is an important tool for imaging of cancer, including skeletal metastases. However, false-positive results can occur in benign diseases such as insufficiency fractures. We report a case of sacral insufficiency fracture in which increased FDG uptake was detected. Correlative CT images obtained by a combined PET/CT scanner excluded a possible false-positive interpretation by revealing the fracture lines at the site of increased FDG uptake.

Is early bladder activity in radionuclide cisternography an indirect sign of spontaneous intracranial hypotension or sequence of lumbar puncture?

Spontaneous intracranial hypotension (SIH) is characterized by severe postural headache and low cerebrospinal fluid (CSF) pressure. Radionuclide cisternography (RC) is of some value in diagnosing CSF leakage causing SIH. However, the sensitivity of RC is too low to demonstrate the site of leakage. In these cases, the early appearance of the radioactivity in the urinary bladder has also been used as an indirect finding in the diagnosis of SIH. The aim of this study was to evaluate the diagnostic reliability of early urinary bladder activity as an indirect sign of SIH. We investigated early bladder activity in 21 patients with suspicion of normal pressure hydrocephalus. Of the 21 subjects, 13 (62%) showed early bladder activity. We demonstrated that early bladder activity is observed in patients without CSF leakage such as normal pressure hydrocephalus. Therefore, this indirect finding of RC is not a reliable finding in diagnosing SIH.

Fluoro-18 fluorodeoxyglucose positron emission tomography/computerized tomography scans in a patient with penile cancer for appropriate therapeutic strategy.

In patients with penile cancer, positron emission tomography (PET) is important for identifying metastatic lesions and for therapeutic strategy planning. By using PET/computerised tomography -CT scanning, more precise localization and attenuation correction is provided by CT as an additional advantage for diagnosis. A 78-year-old man with squamous cell cancer of the glans penis diagnosed after histopathological examination was referred to our Nuclear Medicine Department PET/CT unit by the Urology Department of our Hospital, for investigation of metastases and for therapeutic strategy planning. There was significantly increased focal fluoro-18 fluorodeoxyglucose (18F-FDG) activity (SUV: 18.2) in the glans penile area and slightly increased activity in the right inguinal region which was described as inflammation by the histopathological examination. There was no other increased abnormal 18F-FDG activity. 18F-FDG PET or PET/CT may be used in squamous cell cancer of the penis for the detection of metastases and for therapeutic strategy planning. Finally, invasive procedures such as total bilateral inguinal lymphadenectomy, having a high morbidity, may be avoided.

PET/CT findings in a multicentric form of Castleman's disease.

We report a case of a multicentric form of Castleman's disease (CD). A thoracic computerized tomography (CT) scan showed multiple mediastinal and bilateral axillary lymph nodes. Fluoro-18 fluoro deoxyglucose ((18)F-FDG) positron emission tomography-PET/CT scan demonstrated increased (18)F-FDG accumulation in multiple lymphatic regions and in bilateral pleural areas. The histopathological sampling of an excised left axillary lymph node revealed a multicentric form of CD, of an intermediate (mixed) cell type. The disease, its differential diagnosis and the diagnostic contribution of nuclear medicine imaging, are described.

Compatibility of MRI and FDG-PET findings with histopathological results in patients with focal cortical dysplasia.

PURPOSE: The present study aimed to determine if the specific characteristics of fluorodeoxyglucose-positron emission tomography (FDG-PET) analyses of the FCD subgroups were compatible with the magnetic resonance imaging (MRI) and clinical findings of the patients in these subgroups. METHODS: This study included 71 patients who had a presurgical evaluation workup performed due to drug-resistant seizures, who underwent epilepsy surgery, and who were histopathologically diagnosed with FCD. Relationships involving MRI and FDG-PET findings and clinical data from pathological subgroups and patients were assessed. RESULTS: According to the International League Against Epilepsy (ILAE) classifications of FCD, 28 of the patients were type I and 43 were type II. FCD was visible on the MRI scans of 53 patients, and a majority of this group was classified as type II FCD (n=34). Of these 53 patients, FCD was located in the temporal area of 21 patients, the extratemporal area of 29 patients. Of the patients who exhibited FDG-PET hypometabolism (PET-positive), 23 were classified as temporal, 17 as frontal, 11 showed involvement of the posterior cortex. The age of seizure onset was younger in PET-positive patients (p=0.032), and histopathological analyses revealed that 23 patients had type I FCD and 30 patients had type II FCD. CONCLUSION: PET scans reveal a lesion by showing hypometabolism in patients who have refractory epilepsy and an early age of onset with FCD. The lesions of MRI-negative/PET-positive FCD patients tend to be localized in the temporal lobe and that FCD may be localized in the frontal lobe of MRI-negative/PET-negative patients. However, the histopathological examinations of MRI-positive/PET-positive, MRI-negative/PET-positive, and MRI-negative/PET-negative patients did not exhibit a particular histopathological subtype.