‘Low dose’ 99mTc-Sestamibi for radioguided surgery of primary hyperparathyroidism

AIM

In this study, we evaluated the efficacy of low dose (99m)Tc-Sestamibi administration for radioguided parathyroid surgery in patients with primary hyperparathyroidism (PHPT).

METHODS

Three hundred consecutive PHPT patients were studied between September, 1999 and July, 2003. Pre-operative work-up included (99m)Tc-pertechnetate/(99m)Tc-Sestamibi subtraction scintigraphy and high resolution ultrasonography (US). 37MBq of (99m)Tc-Sestamibi was injected i.v. in the operating suite approximately 10 min prior to the beginning of the surgical procedure for intraoperative radiolocalization; quick parathyroid hormone (QPTH) assays were performed.

RESULTS

Two hundred and seven of the 211 patients selected for minimally-invasive radioguided parathyroidectomy (MIRP) were successfully treated for a solitary parathyroid adenoma (PA) through a 2-2.5 cm skin incision (mean operative time 35 min, mean hospital stay 1.2 days). In the 89 patients selected for traditional bilateral neck exploration (BNE), radioguided surgery was not as successful in the identification of the PA, especially in patients with (99m)Tc-Sestamibi-avid thyroid nodules. Nevertheless, the combination of probe and QPTH measurement was very helpful in patients with multigland disease.

CONCLUSIONS

Low-dose (99m)Tc-Sestamibi administered few minutes before surgery is sufficient for MIRP in patients with high likelihood of a solitary PA and without concomitant (99m)Tc-Sestamibi-avid thyroid nodules. The combination of radioguided surgery and QPTH measurements is very useful in the early identification of unanticipated multigland disease.

Role of 18F-FDG PET–CT imaging for the detection of an unknown primary tumour: preliminary results in 21 patients

PURPOSE

Metastatic cancer of unknown primary origin is a syndrome characterised by a poor prognosis, with a typical survival rate from diagnosis of no longer than 1 year. Only 20-27% of primary tumours are identified by conventional radiological imaging. By contrast, it has been reported that 18F-fluorodeoxyglucose positron emission tomography (FDG PET) allows the identification of 24-40% of otherwise unrecognised primary tumours. To our knowledge, the studies on this topic have been conducted using 18F-FDG PET imaging alone. The aim of this study was to evaluate the potential additional diagnostic role of fused 18F-FDG PET-CT imaging for the detection of metastatic occult primary tumours.

METHODS

The study population consisted of 21 consecutive patients with biopsy-proven metastatic disease and negative conventional diagnostic procedures. Each patient underwent a PET scan, carried out according to a standard procedure (6 h of fasting, i.v. injection of 370 MBq of 18F-FDG and image acquisition with a dedicated PET-CT scanner for 4 min per bed position).

RESULTS

18F-FDG PET-CT detected the occult primary tumour in 12 patients (57% of cases), providing a detection rate higher than that reported with any other imaging modality, including conventional 18F-FDG PET.

CONCLUSION

The favourable results of this study need to be confirmed in larger patient populations with long-term follow-up.

Radioguided surgery of primary hyperparathyroidism using the low-dose 99mTc-sestamibi protocol: multiinstitutional experience from the Italian Study Group on Radioguided Surgery and Immunoscintigraphy (GISCRIS)

This study evaluated the accuracy of (99m)Tc-sestamibi scintigraphy and neck ultrasonography in patients with primary hyperparathyroidism (PHPT) and the role of intraoperative hand-held gamma-probes in minimally invasive radioguided surgery (MIRS) of patients with a high likelihood of a solitary parathyroid adenoma (PA). The study was undertaken under the aegis of the Italian Study Group on Radioguided Surgery and Immunoscintigraphy (GISCRIS).

METHODS

Clinical records were reviewed for 384 consecutive PHPT patients undergoing radioguided surgery using a low dose of (99m)Tc-sestamibi. Selection of patients for MIRS instead of traditional bilateral neck exploration was based on preoperative imaging indicating a solitary PA. (99m)Tc-Sestamibi (37-110 MBq, or 1-3 mCi) was injected in the operating theater 10-30 min before the start of the intervention. Either 11-mm collimated (309 patients) or 14-mm collimated (75 patients) gamma-probes were used. Intraoperative quick parathyroid hormone (IQPTH) assay was used on 308 patients (80.2%).

RESULTS

MIRS was successfully performed on 268 (96.8%) of 277 patients. Conversion to bilateral neck exploration was necessary in 9 patients (3.3%) because of either persistently high IQPTH levels after removal of the preoperatively visualized PA (4 patients), intraoperative frozen-section diagnosis of parathyroid carcinoma (2 patients), or hard-to-remove PA (3 patients). MIRS, which was performed under locoregional anesthesia in 72 patients, required a mean operating time of 37 min and a mean hospital stay of 1.2 d. MIRS was successfully performed also on 32 (78.0%) of 41 patients who had previously undergone thyroid or parathyroid surgery. No major surgical complications were observed in the MIRS group, and there were only 24 cases (11%) of transient postoperative hypocalcemia. The probe was of little help in patients with concomitant (99m)Tc-sestamibi-avid thyroid nodules and not helpful at all in patients with negative scan findings preoperatively. IQPTH measurement helped to disclose some cases of multigland parathyroid disease.

CONCLUSION

(99m)Tc-Sestamibi scintigraphy, especially if combined with neck ultrasonography, is highly accurate in selecting PHPT candidates for MIRS. The low-dose (99m)Tc-sestamibi protocol (which entails a low-to-negligible radiation exposure to the surgical team) is safe and effective for MIRS. MIRS plays a limited role in patients with concomitant (99m)Tc-sestamibi-avid thyroid nodules and should be discouraged in patients with negative (99m)Tc-sestamibi finding preoperatively. IQPTH can be recommended during MIRS to facilitate intraoperative identification of previously undiagnosed multigland parathyroid disease.

Additional value of hybrid PET/CT fusion imaging vs. conventional CT scan alone in the staging and management of patients with malignant pleural mesothelioma

BACKGROUND

Despite being a relatively rare disease, the incidence of malignant pleural mesothelioma (MPM) is expected to increase over the next two decades due to the long time interval elapsing between exposure to causative factors, mainly asbestos, and disease onset. Early disease stages have been reported to benefit from radical surgery. In more advanced disease stages, a multimodality treatment, including various combinations of chemotherapy, external radiotherapy and surgery, may provide some favourable results though the prognosis remains poor. In this regard, an accurate pre-treatment staging plays an important role in offering patients a more appropriate therapeutic planning. In some preliminary studies, (18)F-FDG PET has proven to be able to provide useful information for staging purpose, especially for the detection of metastatic spread to lymph nodes and distant sites.

MATERIAL AND METHODS

In the present study, we investigated 15 consecutive patients with histologically proven MPM by means of conventional 2-mm thickness whole-body CT scan with and without contrast medium in comparison with wholebody (18)F-FDG PET/CT fusion imaging.

RESULTS

(18)F-FDG PET/CT did not provide additional information about the primary tumour (T) compared to CT scan, but identified a higher number of metastatic mediastinal lymph nodes (N) in 6 patients (40% of cases) and unknown metastatic disease to distant sites (M) in 3 patients (20% of cases). On the basis of PET/CT findings, treatment planning was changed in 5 patients (33.3% of cases).

CONCLUSIONS

Our data show that (18)F-FDG PET/CT fusion imaging can play a relevant role in the staging and treatment planning of MPM patients.

Controversies on minimally invasive procedures for radio-guided surgery of parathyroid tumours

The definitive treatment of primary hyperparathyroidism (PHPT) is the surgical approach which traditionally consists of bilateral neck exploration with visualization of at least 4 parathyroid glands and removal of the enlarged ones. However, the most frequent cause of PHPT is a solitary parathyroid adenoma so that a limited neck exploration in order to remove the solitary adenoma alone appears adequate to many surgeons. The recent significant improvements achieved in the pre-operative parathyroid localization techniques, mainly the parathyroid scintigraphy, and the introduction in surgical practice of measurement of quick parathyroid hormone, endoscopic procedures, and intra-operative gamma probes used together specific radiopharmaceuticals allowed to offer the PHPT patient a limited neck exploration as the unilateral neck exploration and the minimally invasive parathyroidectomy. The present article deals with the role of the intra-operative gamma probes used together with specific radio-pharmaceuticals, discussing the principal advantages and disadvantages of each currently used radio-guided approach.

Effects of a somatostatin analogue in occult gastrointestinal bleeding: a case report

We describe the case of a patient with obscure gastrointestinal bleeding and anaemia, who required repeated transfusions for about 1 year. Because of the absence of a certain diagnosis and of a surgical approach indication, we established long-acting octreotide therapy, obtaining clinical stabilisation and interruption of the transfusional need. Withdrawal of long-acting somatostatin analogue therapy was associated with renewal of bleeding that was again successfully stopped by continuous i.v. somatostatin administration followed by re-establishment of the long-acting octreotide therapy. We suggested, in absence of surgical indications and when only palliative therapies are available, a therapeutic approach with long-term SMS analogues in patients with lower digestive bleeding of a known or unknown source.

The early diagnosis of multiple endocrine neoplasia type 1 (MEN 1): a case report

We report the case of a patient presenting amenorrhea, hyperprolactinemia, headache and nuclear magnetic resonance (NMR) evidence of pituitary macroadenoma. The family history revealed that the patient's father had had a referred sporadic insulinoma, removed 25 yr before without evidence of other endocrine disorders. Physical examination evidenced a slight neck enlargement. Among biochemical and endocrinological assays performed, only hyperprolactinemia was observed. Neck ultrasonography (US) revealed a parathyroid enlargement and a 99mTcO4/MIBI scan showed two hyperplasic lesions. Considering the diagnostic suspect of multiple endocrine neoplasia (MEN1), we performed abdominal US and NMR studies, showing a pancreatic lesion compatible with neuroendocrine tumor. A total body 111In-DTPA-d-Phe1 -octreotide scan (Octreoscan) was also carried out, evidencing no pituitary tumor uptake but high uptake of the abdominal lesion. After surgery, the histological examination confirmed the two parathyroid adenomas and four non-functioning pancreatic neuroendocrine tumors. When the patient was admitted for studying the pituitary lesion and for planning the opportune therapy, an early and partially subclinical stage of MEN1 was identified, potentially already clear but otherwise undiagnosed, and the genetic state of the patient's relatives, as possible carriers of DNA mutation, was checked. The DNA study for germline mutations confirmed the clinical diagnosis of MEN1 syndrome in the patient and evidenced the same MEN1 mutation in her father and twin sister. In this case report, we would like to underline that, still today, a correct anamnesis and physical examination are the cornerstone of clinical approach to the patient. Furthermore, initial good practice approach is necessary to plan the diagnostic iter, enabling clinicians to decide upon the best orientation and interpretation of the results among several complicated and expensive exams.

Restaging after neoadjuvant chemoradiotherapy for rectal adenocarcinoma: role of F18-FDG PET

Multimodality treatment of loco-regional advanced rectal cancer has demonstrated to improve local control and overall survival. Proctoscopy, digital rectal examination (DRE), computer tomography (CT), endorectal ultrasound (ERUS), and magnetic resonance imaging (MRI) cannot correctly detect downstaging in rectal tumors after chemo radiation therapy (CRT). New imaging techniques, like 18F-FDG PET, may play some role in predicting the pathologic response to CRT before surgical resection. Aim of the present study was to further investigate the accuracy and predictive value of 18F-FDG PET in a large series of patients with rectal cancer treated with preoperative intensified CRT. Between January 2000 and December 2003, 81 patients with histologically proven adenocarcinoma in clinical stage II-III disease, according to criteria of TNM classification, were included in this study. All patients were submitted to diagnostic staging workup with DRE, proctoscopy with biopsy, ERUS, CT scan of the abdomen and pelvis or pelvic MRI plus liver ultrasonography, coloscopy or barium colonic enema. One month later the end of CRT all patients were submitted to diagnostic restaging work-up (DRW) and 18F-FDG PET. Surgery was performed 8-9 weeks after the end of CRT and pathologic stage was defined. Moreover a pathologic assessment of tumor regression was made with tumor regression grade score (TRG). PET correctly identified 22/28 (79% specificity) patients with complete pathologic response (pCR). However, sensitivity was 45% (24/53) while PPV, and NPV were equal to 77 and 43%, respectively. Total PET accuracy rate was 56%. PET sensitivity increased from 45 to 56% if the end-point was pCR, or TRG score, respectively. The best correlation was found between PET findings and pathologic stage (P <0.01) or TRG score (P <0.01). The accurate identification of rectal cancer patients with major pathological response after preoperative CRT further supports the necessity of designing prospective studies with new and more accurate was imaging technologies with the main object of offering conservative treatment in responder patients.

Minimally invasive radioguided parathyroidectomy: an attractive therapeutic option for elderly patients with primary hyperparathyroidism

BACKGROUND AND AIM

Surgery for primary hyperparathyroidism (PHPT) due to a solitary parathyroid adenoma (PA) is moving from traditional bilateral neck exploration (BNE) towards the use of limited neck exploration. The aim of the present study was to define the efficacy of minimally invasive radioguided surgery (MIRS) in PHPT patients with a high probability of a solitary PA with particular regard to benefits achievable in elderly patients.

PATIENTS AND METHODS

The study population included a total of 266 consecutive PHPT patients who had undergone surgery at our centre between September 1999 and February 2003. Preoperative imaging consisted of [Tc]pertechnetate/Tc sestamibi (TcO4/sestamibi) scintigraphy and neck ultrasound obtained in the same session. One hundred and eighty-seven patients from the whole series (75 of whom were older than 65 years) with a high scan/ultrasound probability of a solitary PA, a high PA sestamibi uptake, and a normal thyroid gland were selected for MIRS. The other 79 patients were selected for traditional BNE. The intra-operative technique was based on the injection of a low dose (37 MBq) of sestamibi in the operating theatre a few minutes before the beginning of intervention and on the use of an 11 mm collimated gamma probe.

RESULTS

MIRS was successfully performed in 97.8% of all PHPT patients selected for this type of surgery and, in particular, in 100% of the subgroup (n=75) of elderly patients. MIRS required a mean operating time of 35 min and a mean hospital stay of 1.2 days; that is, approximately half of that required for traditional BNE. Moreover, local anaesthesia was successfully performed in 27 patients, 19 of whom were >65 years with concomitant invalidating diseases contraindicating general anaesthesia. No major surgical complications were recorded. Transitory hypocalcaemia was observed in 9% of cases treated with MIRS compared with 27% of patients treated with BNE.

CONCLUSION

MIRS can be accurately planned in elderly PHPT patients with a solitary PA on the basis of a TcO4/sestamibi scan and neck ultrasound. MIRS has been proven to be safe and effective in our experience, and allows a significant reduction of operating and recovery time, as well as the possibility of using local anaesthesia, especially in elderly patients with concomitant invalidating diseases.

Natural history, diagnosis, treatment and outcome of papillary thyroid microcarcinoma (PTMC): a mono-institutional 12-year experience

The clinical and histopathological records of 149 consecutive patients with papillary thyroid microcarcinoma (PTMC), homogeneously studied and operated on by the same surgeon in the period 1990 to 2001, were reviewed. After a mean 6.5-year follow-up, three cases of loco-regional recurrence (2%) were observed. These three patients had all undergone partial thyroidectomy only and tumour relapse occurred in the residual thyroid tissue. No recurrence was observed in patients treated by total thyroidectomy and I. At variance with other reported series, no lymph node recurrence was observed in our series, in particular in the group of 23 patients with evidence of nodal metastases at initial diagnosis (three of whom were revealed by I scan after surgery). Therefore, a preventive effect of I treatment in our patient population can be hypothesized. However, prolonged follow-up will be necessary to clarify this. Due to the inability of current imaging modalities to select pre-operatively PTMC patients at risk for recurrence (presence of thyroid capsular invasion, multifocality and microscopic lymph node metastases), it appears reasonable to offer the patient total thyroidectomy when a pre-operative diagnosis of PTMC is reached. Moreover, the policy of our thyroid cancer centre is that, in these patients, post-surgical I scan should be obtained in order to detect unknown metastatic deposits, and I treatment should also be considered in patients with poor clinical and histopathological prognostic factors. In contrast, in patients operated on for benign thyroid disease and with delayed diagnosis of PTMC at definitive histopathological examination, re-operation might be avoided in the presence of unifocal disease without thyroid capsular invasion and with ultrasound-'normal' residual thyroid tissue. Close clinical and ultrasound follow-up is recommended, especially in patients who have undergone conservative surgery only.

[Role of CT/111In-octreotide SPECT digital fusion imaging in the localization of loco-regional recurrence of medullary thyroid carcinoma]

The case of a female patient affected by a sporadic medullary thyroid carcinoma (pT1N1aM0 at the onset) is reported. The patient had been initially treated by total thyroidectomy and lymphadenectomy of the central and lateral portions of the neck. During the following 30 years of follow-up, the patient experienced 3 consecutive loco-regional tumoral relapses. At the moment of each relapse, an increase of serum calcitonin levels has anticipated the subsequent detection of tumor deposits at clinical and radiological examination (ultrasound, CT scan). It is well known that, after multiple operations, the structures of the neck can present anatomical distortion and fibrosis that can interfere with ultrasound and CT scan interpretation. In the present patient, a scintigraphic examination with 111In-octreotide, that is a specific radio-tracer for somatostatin receptors, allowed to correctly visualize a tumoral relapse in the left thyroid bed, located in deep para-tracheal planes: in that site the CT scan only showed an unspecific solid mass. Furthermore, the utilization of a digital image fusion technique for CT scan and 111In-octreotide SPECT, furnished useful information for the purpose of planning an accurate re-intervention, both morphologic information (mass size, precise site of the mass and their relationship with the surrounding anatomical structures) and functional information (biological characterization of the mass that was classified as a neuroendocrine tumoral deposit with high density of somatostatin receptors.

Radionuclide gastroesophageal motor studies

Disorders of the upper digestive tract have a high impact on modern society, in terms of both direct and indirect health care costs and of social burden. The most common presenting symptom is either dysphagia or dyspepsia. Discriminating specific diagnoses within this wide group of diseases requires sound clinical judgment and application of procedures to distinguish organic from nonorganic disease and to further characterize the functional or motility disturbance of nonorganic diseases. Non-radionuclide-based diagnostic techniques include both noninvasive tests (upper gastrointestinal barium series, ultrasonography, and breath test for gastric emptying) and invasive procedures (fiberoptic endoscopy, esophagogastroduodenoscopy, pharyngeal manometry, stationary esophageal manometry, 24-h pH monitoring, esophageal biliary reflux monitoring, multichannel intraluminal impedance, and electrogastrography). Some of these techniques are not well tolerated by patients or not widely available. Radionuclide transit/emptying scintigraphy provides a means of characterizing exquisite functional abnormalities with a set of low-cost procedures that are easy to perform and widely available, entail a low radiation burden, closely reflect the physiology of the tract under evaluation, are well tolerated and require minimum cooperation by patients, and provide quantitative data for better intersubject comparison and for monitoring response to therapy. Despite the relatively low degree of standardization both in the scintigraphic technique per se and in image processing, these methods have shown excellent diagnostic performance in several function or motility disorders of the upper digestive tract. Dynamic scintigraphy with a radioactive liquid or semisolid bolus provides important information on both the oropharyngeal and the esophageal phases of swallowing, thus representing a useful complement or even a valid alternative to conventional invasive tests (such as stationary esophageal manometry) for evaluating abnormalities of oropharyngoesophageal transit. Clinical applications of esophageal transit scintigraphy include disorders such as nutcracker esophagus, esophageal spasm, noncardiac chest pain of presumed esophageal origin, achalasia, esophageal involvement of scleroderma, and gastroesophageal reflux and monitoring of response to therapy (either medical or surgical treatment of disease-for example, organic disease such as esophageal cancer). Scintigraphy with a radiolabeled test meal represents the gold standard for evaluating gastric emptying, whereas more recent radionuclide methods include dynamic antral scintigraphy and gastric SPECT for assessing gastric accommodation. Clinical applications of gastric-emptying scintigraphy include, among others, evaluation of patients with dyspepsia and evaluation of gastric function in various systemic diseases affecting gastric emptying. The present review includes the proposal of clinical algorithms for evaluating patients with the main disorders of the upper digestive tract. These algorithms, originally derived from available literature, have been developed on the basis of a vast clinical experience in conjunction with the specialists more deeply involved in the care of patients with such disorders (medical and surgical gastroenterologists and nuclear medicine physicians). The role of radionuclide gastroesophageal motor studies is clearly identified in the various steps of patients' management, from the initial diagnostic approach to functional characterization to postoperative follow-up or monitoring of medical therapy.

Autoimmune diabetes mellitus, Hodgkin's disease and Graves' ophthalmopathy in a patient with 8.1 ancestral haplotype

In this report, we describe the case of a 43-year-old woman affected by type 1 diabetes mellitus diagnosed 8 years before, who developed Graves' disease 2 years after chemotherapy and mantle radiotherapy treatment for Hodgkin's disease. Bilateral Graves' ophthalmopathy appeared four months before our observations. Intravenous methyl-prednisolone therapy was started, but was interrupted due to severe metabolic failure. Autoantibodies (anti-islet cells, anti-thyroid, thyroid-stimulating, non-organ-specific) were positive. Since the clinical picture suggested a genetic immunological ground predisposing to autoimmunity, we evaluated her HLA haplotype. Genomic typing of the patient permitted identification of the 8.1 ancestral haplotype, a Caucasoid haplotype unique in its association with many immunopathological diseases. Moreover, we also observed a haplotype unusual in Caucasians, trans DRB1*1101, DQA1*0103, DQB1*0603. To our knowledge, HLA-related genetic risk of developing thyroid autoimmunity after neck irradiation has never been studied. Although we cannot confirm a direct association between the 8.1 ancestral haplotype or DRB1*1101, DQA1*0103, DQB1*0603 and the diseases described, we suggest considering immunological parameters and HLA typing in candidate patients for mantle radiation therapy for Hodgkin's disease or other tumors. HLA haplotype determination could be useful in identifying the patients at raised risk of developing autoimmune diseases after irradiation, thus permitting a more appropriate follow-up schedule.

Sentinel node biopsy for breast cancer: is it already a standard of care? A survey of current practice in an Italian region

BACKGROUND

Although sentinel node biopsy (SNB) is becoming the standard approach for axillary staging in patients with small breast cancer, criteria for patient selection and some technical aspects of the procedure have yet to be clearly defined. The aim of the present survey was therefore to investigate the way in which SNB is used by general surgeons working in the Veneto region, Italy.

METHODS

A 29-item questionnaire regarding various aspects of SNB practice was mailed to surgeons in charge of breast surgery in all the 56 surgical centres of the region.

RESULTS

The rate of response to the questionnaire was 82.1% (n = 46); 69.6% (n = 32) of the respondents routinely perform SNB in their clinical practice. Most of the interviewed surgeons (93.5%) expressed the belief that the acceptable false negative rate should be < or =5%. However, among the surgeons who perform SNB, only 34.4% performed more than 20 SNB during the learning phase. Indications are limited to tumours of < or =1 cm by 31.2% (n = 10) of respondents, < or =2 cm by 46.9% (n = 15) and < or =3 cm by 21.9% (n = 7). Almost all respondents (93.7%) agreed that a clinically positive axilla is a contraindication to SNB, while opinions differed widely concerning other potential contraindications. In most of the centres considered, SN identification is undertaken on the day before surgery using a subdermal injection of 30-50 MBq of 99mTc-albumin-nanocolloid followed by lymphoscintigraphy.

CONCLUSIONS

SNB is currently performed in the majority of hospitals in the Veneto region. However, the training phase and criteria used for patient selection differ from centre to centre. Certified training courses and shared guidelines are therefore highly desirable.

Role of anti-granulocyte Fab??? fragment antibody scintigraphy (LeukoScan) in evaluating bone infection: acquisition protocol, interpretation criteria and clinical results

Scintigraphy using anti-granulocyte Fab' fragment (LeukoScan) was performed in a series of 220 consecutive patients with suspected bone infection referred to our centre between September 1999 and June 2002. Two protocols were compared for interpreting scans: (1) evaluation of early 4 h imaging alone (protocol A), and (2) evaluation both of early and delayed 24 h imaging (protocol B). Protocol A and protocol B showed equal values of sensitivity (91.9% in patients with diabetic foot and 84.2% in patients with joint prosthesis/peripheral bone implants). Conversely, specificity was higher adopting protocol B than protocol A: 87.5% vs 75.0% in patients with diabetic foot, and 85.7% vs 76.2% in patients with joint prosthesis/peripheral bone implants, respectively. In particular, an improvement in specificity using protocol B was found in those patients with infection and with only a mild LeukoScan uptake in the early 4 h imaging: in these patients an increasing uptake intensity pattern observed in the delayed 24 h imaging was indicative of infection while a decreasing pattern suggested a negative result. Instead, the evidence of a high uptake intensity in the early LeukoScan imaging was a strong indicator of infection and delayed imaging in these cases did not further improve specificity. In conclusion, in our experience, LeukoScan showed high sensitivity in diagnosing bone infection in patients with diabetic foot and joint prosthesis or other peripheral bone implants. Moreover, in patients with an early high LeukoScan uptake intensity further delayed images appears unnecessary for the purpose of diagnosing infection. In contrast in patients with an early mild LeukoScan uptake intensity only, delayed imaging appears to be recommendable for improving specificity.

Optimized procedure of real-time systemic leakage monitoring during isolated limb perfusion using a hand held gamma probe and 99mTc-HSA

Isolated limb perfusion (ILP) therapy using a combination of tumour necrosis factor alpha (TNF) and cytostatic agents in hyperthermic conditions has proven to be effective in treating cancers limited to limbs or to a single organ such as the liver. A critical step for ILP is the accurate and real-time monitoring of that TNF toxic effects become relevant when overcoming the 10% limit of the 'effective' therapeutic dose administered during ILP. The most diffuse procedure for systemic leakage monitoring is based on the utilization of human soluble serum albumin (HSA) labelled with 131I and an external scintillation detector. In order to overcome some drawbacks connected with the properties of 131I, we developed a new procedure based on the utilization of HSA labelled with 99mTc in combination with a hand held gamma probe used as a detector. Our procedure consists of the following steps: (1) a 99mTc-HSA dose standardized as 0.5 MBq x kg(-1) body weight is injected into the ILP circuit before TNF administration; (2) a hand held gamma probe is placed over the pre-cordial area in a zone pre-marked on the patient's skin during a simulation test; (3) 48-72 h before ILP, a simulation test is obtained using a 99mTc-HSA dose corresponding to 10% of the dose calculated for ILP (i.e., 0.05 MBq x kg(-1) body weight); (4) during the simulation test the maximum count-rate zone detected on the pre-cordial area is marked on patient's skin; (5) a 60 min time-activity curve corresponding to the circulating 99mTc-HSA radioactivity effective decay is calculated and fitted; and (6) this time-activity curve is used to compensate for the leakage systemic counting observed during ILP. In order to compare the external, probe counting with the circulating radioactivity, in the first 10 patients from a total series of 43 treated patients, the results of external, probe monitoring were compared with the results of patient blood and perfusion circuit samples taken simultaneously every 5 min and measured by a laboratory gamma counter placed in the operating theatre. A good correlation was found between the two methods (R2 = 0.965, P < 0.01). It is concluded that the proposed procedure, based on the combination of 99mTc-HSA as the radiotracer and a hand held gamma probe as the detector, appears to be technically simple and accurate enough in the real-time monitoring of perfusion leakage in ILP cancer therapy. Moreover, using 99mTc-HSA as the radiotracer, the risk of radioactive contamination is significantly lower in comparison with 131I-HSA.

TNF-based limb perfusion for cutaneous melanoma in transit metastases: suggestions for modification of the perfusional schedule

Isolated limb perfusion (ILP) is currently considered the standard treatment for melanoma patients with extensive in-transit disease, and L-PAM, combined or not with TNF, represents the most active drug. We here report on our clinical experience with TNF-based limb perfusion. Thirty-seven stage III patients underwent TNF-based limb perfusion, 22 with bulky disease, 15 with recurrences after perfusion with L-PAM. Ten patients were enrolled in a phase I-II study and treated with escalating doses of TNF (0.5-3 mg). The impact of disease burden, temperature, perfusion duration was assessed on tumor response. No postoperative death was observed. No significant systemic toxicity was recorded. Locoregional toxicity was G5 in one patient, G3 in 2, G2 in 9 and G1 in 25. Twenty-four (66%) patients had complete response, 11 (31%) partial and 1 (3%) no change. After a median follow-up of 20 months 14 (38%) patients are NED, 10 (27%) are AWD and 13 (35%) DOD. No significant statistical difference for tumor response were seen for disease burden, ILP temperatures and duration. Our results showed that it is possible to modify the perfusion schedule, without compromising the response rate but with lower cost and toxicity.

[New perspectives in diagnosis and therapy of endocrine gastroenteropancreatic (GEP) tumors with somatostatin analogues]

In the last decade important progresses have been obtained in the diagnosis and therapy of endocrine gastroenteropancreatic (GEP) tumors, mainly derived from the somatostatin receptors characterization and the introduction of long acting somatostatin analogues. Receptorial scintigraphy with radio-labeled analogues (Octreoscan) is the first choice investigation for staging and follow-up of endocrine GEP tumors, thanks to the high sensitivity in revealing the primary tumor and metastases, and for its capability to reveal lesions that are not identified by other imaging methods. Moreover, somatostatin analogues uptake by tumors allow us to use radiopharmaceutical compounds for advanced disease treatment. Between the radio-labeled drugs until now studied, interesting results have been obtained by DOTA-lanreotide (MAURITIUS), DOTA0 Tyr3-octreotide (DOTATOC) and DOTA0 Tyr3-octreotate, bound to beta-emitting radio-isotope suitable for therapeutic use. In the field of the pharmacological therapy of GEP tumors, the clinical trials show that somatostatin analogues reduce the symptoms related to functionally active tumors and stabilize or slow tumor growth improving the patient quality of life. Although somatostatin analogues alone could not be able to cure GEP tumors, their early utilization in association with surgical debulking of primary tumor and metastases, embolization or chemoembolization, and interferon, chemotherapy and radio-metabolic therapy (mainly directed to the destruction of micrometastases), increases the possibility of a radical therapeutic intervention. The continuous evolution of pharmacological research provides always new analogues (octreotide LAR, lanreotide, vapreotide, BIM-23244, BN 81644, PTR-3173, BIM-23A387, SOM-230, etc.) with different pharmacokinetic and receptorial properties and acting with more effectiveness in the different individual clinical situations. In this context there have been recently introduced also the "chimeric" analogues. On the other hand, the widespread utilization of molecular biology and immunohistochemical methods can allow, in perspective, to better define the receptorial pattern of individual endocrine tumors, after their surgical removal. The necessity to integrate endocrinological, nuclear medicine, surgical, oncologic and laboratory competencies behaves a multidisciplinary approach based on the utilization of diagnostic-therapeutic protocols supplying comparable results. It does not appear unjustified to expect, in the future, a scenery of more "individual" and more effective therapies for patients affected by GEP tumours.

Preoperative localization and radioguided parathyroid surgery

Clinical or subclinical hyperparathyroidism is one of the most common endocrine disorders. Excessive secretion of parathyroid hormone is most frequently caused by an adenoma of >or=1 parathyroid gland. Unsuccessful surgery with persistent hyperparathyroidism, due to inadequate preoperative or intraoperative localization, may be observed in about 10% of patients. The conventional surgical approach is bilateral neck exploration, whereas minimally invasive parathyroidectomy (MIP) has been made possible by the introduction of (99m)Tc-sestamibi scintigraphy for preoperative localization of parathyroid adenomas. In MIP, the incision is small, dissection is minimal, postoperative pain is less, and hospital stay is shorter. Localization imaging techniques include ultrasonography, CT, MRI, and scintigraphy. Parathyroid scintigraphy with (99m)Tc-sestamibi is based on longer retention of the tracer in parathyroid than in thyroid tissue. Because of the frequent association of parathyroid adenomas with nodular goiter, the optimal imaging combination is (99m)Tc-sestamibi scintigraphy and ultrasonography. Different protocols are used for (99m)Tc-sestamibi parathyroid scintigraphy, depending on the institutional logistics and experience (classical dual-phase scintigraphy, various subtraction techniques in combination with radioiodine or (99m)Tc-pertechnetate). MIP is greatly aided by intraoperative guidance with a gamma-probe, based on in vivo radioactivity counting after injection of (99m)Tc-sestamibi. Different protocols used for gamma-probe-guided MIP are based on different timing and doses of tracer injected. Gamma-probe-guided MIP is a very attractive surgical approach to treat patients with primary hyperparathyroidism due to a solitary parathyroid adenoma. The procedure is technically easy, safe, with a low morbidity rate, and has better cosmetic results and lower overall cost than conventional bilateral neck exploration. Specific guidelines should be followed when selecting patients for gamma-probe-guided MIP.

Role of gamma probes in performing minimally invasive parathyroidectomy in patients with primary hyperparathyroidism: optimization of preoperative and intraoperative procedures

OBJECTIVE

In the last decade, surgery of primary hyperparathyroidism (HPT) due to a solitary adenoma has moved on from the traditional wide bilateral neck exploration (BNE) to more limited approaches such as unilateral neck exploration and minimally invasive parathyroidectomy.

DESIGN

To define the role of intraoperative gamma probe and injection of a low (99m)Tc-MIBI dose in performing minimally invasive radio-guided surgery (MIRS) in HPT patients with a solitary parathyroid adenoma.

METHODS

From September 1999 to July 2002, 214 patients with primary HPT entered the study. All patients were preoperatively investigated by a (99m)Tc-pertechnetate/MIBI subtraction scan and high-resolution neck ultrasound. The intraoperative technique we developed differs from other previously described techniques being based on the injection of a low (37 MBq) MIBI dose in the operating theatre a few minutes before the beginning of intervention.

RESULTS

On the basis of scan/ultrasound findings 147 patients were selected for a MIRS and 144 of them (98%) were successfully treated by this approach: a solitary parathyroid adenoma was removed through a small 2-2.5 cm skin incision with a mean operative time of 35 min, and a mean hospital stay of 1.2 days. In the other 67 patients with scan/ultrasound evidence of concomitant nodular goiter (n=45) or multi-gland disease (n=13) or with a negative scan (n=9), the gamma probe was utilized during a traditional BNE. A low 37 MBq MIBI dose proved to be sufficient to perform a MIRS; moreover it delivered to the patient and surgeon a low, negligible, radiation exposure dose.

CONCLUSIONS

The combination of a (99m)Tc-pertechnetate/MIBI subtraction scan and neck ultrasound appears to be an accurate imaging protocol in selecting primary HPT patients as candidates for a MIRS. A MIBI dose as low as 37 MBq injected in the operating theatre just before the start of surgery appears to be adequate to perform radio-guided surgery.

Importance of radio-guided minimally invasive parathyroidectomy using hand-held gamma probe and low (99m)Tc-MIBI dose. Technical considerations and long-term clinical results

AIM

(99m)Tc-MIBI radio-guided surgery results, obtained in a group of 141 patients with primary hyperparathyroidism (HPT), are reported.

METHODS

All patients were preoperatively evaluated by a single day protocol based on double-tracer parathyroid scintigraphy and neck ultrasound, and then operated by the same surgical team. In 102 patients (72.3%) with a high scan/ultrasound probability of solitary parathyroid adenoma and normal thyroid gland, a minimally invasive radio-guided surgery was planned. In the other 39 patients (27.7%) with scan/ultrasound evidence of multi-glandular disease (n=8) or concomitant nodular goiter (n=31), the intraoperative gamma probe was used during a standard bilateral neck exploration. Intraoperative quick parathyroid hormone (PTH) levels were routinely measured. The minimally invasive radio-guided surgery technique we developed, consisted of: a) injection of a low 37 MBq (99m)Tc-MIBI dose in the operative theatre during anaesthesia induction, b) patient's neck scan with a hand-held gamma probe just before the surgical cut to localize the cutaneous projection of the parathyroid adenoma, c) intraoperative probe detection of the parathyroid adenoma and its removal through a small 2-2.5 cm skin incision.

RESULTS

Minimally invasive radio-guided surgery was successfully performed in 99/102 patients (97.0%). The gamma probe was particularly useful in patients with an ectopic parathyroid adenoma in the upper mediastinum (n=11) or to the carotid bifurcation (n=1) or located deep in the neck (n=8). Minimally invasive radio-guided surgery was also obtained in 18/23 patients who had previously undergone thyroid/parathyroid surgery. The mean operative time for minimally invasive radio-guided surgery was 38 min. No major surgical complication was recorded. Conversion to bilateral neck exploration was required in only 3 cases because of intra-operative diagnosis of parathyroid carcinoma (n=2), and persistence of elevated quick PTH levels after removal of the preoperatively visualized parathyroid adenoma (n=1). Among patients treated by standard bilateral neck exploration, the gamma probe was useful in localizing a thymical enlarged parathyroid gland in 1 patient with multi-glandular disease, a parathyroid adenoma located deep in the neck in 4 patients with concomitant nodular goiter and an ectopic parathyroid adenoma to the carotid bifurcation in another. However, in some other patients with a parathyroid adenoma located near to the thyroid, it was difficult to intraoperatively distinguish the parathyroid adenoma from a MIBI avid thyroid nodule.

CONCLUSION

It can be concluded that: (a) in primary HPT patients with high scan/ultrasound probability of solitary parathyroid adenoma and normal thyroid gland, the gamma probe appears to be an effective, rapid and safe technique to perform minimally invasive radio-guided surgery; b) a (99m)Tc-MIBI dose as low as 37 MBq appears to be adequate to successfully perform radio-guided surgery; c) the measurement of quick PTH is recommended during minimally invasive radio-guided surgery; d) minimally invasive radio-guided surgery can be performed also in HPT patients with previous parathyroid/thyroid surgery thus limiting surgical trauma; e) with the possible exception of parathyroid adenoma located in ectopic sites or deep in the neck, the gamma probe technique does not seem recommendable in HPT patients with concomitant nodular goiter.