Luca Filippi

Incidental detection of colorectal cancer Via 18F-Choline PET/CT in a patient with recurrent prostate cancer: Usefulness of early images

A 74-year-old man with history of prostate cancer underwent F-choline PET/CT for restaging. Early acquisition of the pelvic region revealed intense uptake in prostate, with infiltration of the posterior wall of the bladder. Furthermore, focal uptake in the thickened anterior wall of the rectum was detected. Whole-body scan at 60 minutes confirmed early findings in pelvis, although the infiltration of the bladder was no more evident due to interference of radioactive urine. Biopsy demonstrated the presence of colorectal carcinoma. The dual-phase protocol resulted in significant clinical impact to clearly characterize focuses of abnormal F-choline uptake in the pelvic region.

Usefulness of dual-time point imaging after carbonated water for the fluorodeoxyglucose positron emission imaging of peritoneal carcinomatosis in colon cancer.

BACKGROUND Fluorodeoxygluose (FDG) positron emission/computed tomography (PET/CT) is emerging as a useful tool for the diagnosis of peritoneal carcinomatosis (PC). In this study, we assessed whether dual-time point imaging can improve the accuracy of FDG PET/CT for the diagnosis of PC after colon rectal cancer (CRC). METHODS Thirty-nine patients with past history of CRC were evaluated. Whole-Body PET/CT scan was acquired 1 hour after tracer injection. If one or more focal areas of increased FDG uptake (standardized uptake value, SUV max>2.5) were found in the abdomen, 1 L of carbonated water was orally administered to patients and a delayed scan of the abdominal region was acquired at 2 hours. The SUV max and the mean Delta (Δ) SUV were calculated. The scintigraphic results were compared with the results of colonoscopy and histology and with the clinical follow-up. RESULTS Thirteen out of the 39 patients did not show any significant area of FDG uptake at the whole-body scan. The remaining 26 patients showed an overall number of 27 sites of focal increased uptake, showing a mean SUV max of 6.5+3.3. Late scan of the abdomen showed vanishing spots in 11 cases. Focal and increasing FDG uptake was found in 15 subjects (for an overall number of 16 sites) with SUV max of 15.6+4 and mean Δ SUV of +26.3%±7.5%. In these cases, final diagnosis was PC in 10 patients (according to cytology or histology) and dysplastic polyp in 5 cases. No significant difference in Δ SUV was found between patients with PC and those with polypoid formations. CONCLUSIONS According to our results, dual-time point imaging after carbonated water may increase the accuracy of FDG PET/CT for the imaging of PC in patients affected by CRC.

Usefulness of scintimammography with tc-99m MIBI in clinical practice.

Radiographic mammography (MM) is routinely used to diagnose breast cancer. MM has a number of well-known limitations, especially in cases of a dense or dysplastic breast. Scintimammography (SM) with Tc-99m MIBI has been successfully used as a useful complement to MM. The authors report a case of a 57-year-old woman with MM with tiny calcifications in the left breast, which were classified by the radiologist as probably benign lesions. SM with Tc-99m MIBI showed a focal area of increased uptake in the upper outer quadrant of the left breast. On the basis of SM results, an excisional biopsy was performed and pathologic examination revealed infiltrating ductal carcinoma.

18F-FDG PET-derived parameters as prognostic indices in hepatic malignancies after 90Y radioembolization: is there a role?

The liver is a site of prominent metastasization for many tumours, especially breast and colorectal cancers [1]. Unfortunately, despite many advances in diagnosis and therapy, the prognosis of both primary and secondary hepatic tumours remains poor. Surgery is the most effective approach, but it can often be impracticable due to the anatomic location of the lesions or the massive involvement at presentation. Several treatment modalities both systemic and loco-regional (ethanol injection, radiofrequency ablation, cryoablation, transarterial chemoembolization) have been evaluated [2, 3]. In recent years, Y radioembolization (RE) has emerged as a novel procedure used for the treatment of primary or secondary hepatic lesions. Y, embedded in resin or glass microspheres, is infused directly into the circulation through angiographic catheters placed in the hepatic arteries [4]. Y spheres, once implanted in the liver, can release a significant radiation burden to the neoplastic cells with a relatively low dose to the normal parenchyma due to the different vascularization pattern. To assess tumour response to YRE, Response Evaluation Criteria In Solid Tumours (RECIST) has been largely used [5], but it can present some limitations, since various periand endotumoural processes can occur after the procedure, including oedema, haemorrhage and ring enhancement, which can confound interpretation of response. Besides RECIST, other morphological criteria have been proposed [6]. On the other hand, 2-[F]fluorodeoxyglucose (FDG) PET/CT is a wellestablished diagnostic tool in many oncological scenarios [7]. Although it plays a limited role in the case of non-FDG-avid lesions such as some neuroendocrine tumours and welldifferentiated hepatocellular carcinoma, FDG PET appeared to be useful in detecting metabolic response to Y RE, especially in cases of colorectal and breast cancer metastases to the liver [8, 9]. Regarding the prognostic value of a PET scan, a strict relationship between FDG uptake as measured by the maximum standardized uptake value (SUVmax) and some cellular characteristics of tumours has been reported [10]. Therefore, SUVmax and its changes have been traditionally taken into account as prognostic indicators of tumour response after treatment. Furthermore, PET Response Criteria in Solid Tumors (PERCIST) criteria have been recently introduced to more accurately define the metabolic response of tumours to the therapies [11]. Haug and colleagues published research on the role of FDG PET in predicting survival after Y RE in a cohort of 58 patients with hepatic metastases from breast cancer [12]. FDGPETwas performed at baseline and 3months after the procedure. To evaluate the response of the disease to treatment, the authors applied modified PERCIST criteria. According to the unmodified PERCIST, the change of SUVmax in the two hottest lesions per organ is considered. On the contrary, Haug et al. based their definition of the response on the summed percentage change in the SUVmax in up to five of the most prominent hepatic lesions, demonstrating that response assessed with this approach correlated significantly with survival after Y RE. More recently, Camacho et al. confirmed a significant correlation between overall survival and metabolic response assessed 3 months post procedure by PERCIST criteria in patients with cholangiocarcinoma [13]. It is well known that SUVmeasurements can be affected by many issues, such as the reconstruction algorithm, the scanner O. Bagni : L. Filippi Department of Nuclear Medicine, Santa Maria Goretti Hospital, Latina, Italy

Tumor Thrombus in the Renal Vein from an Adrenal Metastasis of Lung Cancer: 18FDG PET/CT Findings

Tumor thrombus is a rare complication of solid cancer. The authors report a case of a 76-year-old woman presenting a thick walled cystic mass in the lower lobe of the left lung. 18FDG positron emission tomography (PET)/computed tomography (CT) was performed, showing tracer accumulation in the wall of the pulmonary lesion and in the mediastinal and hilar lymph nodes. Moreover, PET/CT depicted a gross mass in the left adrenal gland and a hypermetabolic focus corresponding to the anatomic location of the left renal vein. Contrast-enhanced CT, subsequently performed, confirmed PET findings in the lung, lymph nodes, and adrenal glands, also demonstrating marginal enhancement and intraluminal filling defect in the left renal vein, which was interpreted as tumor thrombus due to the 18FDG uptake at PET scan. CT-guided biopsy of the mass was positive for poorly differentiated carcinoma. 18FDG PET can be useful to diagnose tumor thrombus in oncological patients.

An unusual case of spleen metastasis from carcinoma ex pleomorphic adenoma of the parotid gland

Carcinoma ex pleomorphic adenoma is a rare tumor arising from the salivary glands that spreads through direct extension, through the lymphatic vessels, and, rarely, hematogenously. When distant metastases have been found, they have been reported mainly in the lung. We present an unusual case of carcinoma ex pleomorphic adenoma of the parotid gland with splenic metastases. The patient presented with a primary carcinoma ex pleomorphic adenoma of the parotid gland and he underwent a total parotidectomy with laterocervical lymphadenectomy ipsilateral and adjuvant radiation therapy to the right parotid area. One year later, the patient showed an ipsilateral supraclavicular lymph node recurrence, treated with surgery and radiation therapy. Two more years later, the patient developed lung and splenic lesions, detected through CT and PET. He underwent splenectomy and pathologic assessment of the specimen showed metastatic carcinoma ex pleomorphic adenoma. To our knowledge, there is no reported case of a carcinoma ex pleomorphic adenoma metastasizing to the spleen. Patients treated for carcinoma ex pleomorphic adenoma should be investigated for distant metastases with a long-term follow-up examination for local and distant metastases and new splenic lesions in these patients should be investigated.

18F-Fluorodeoxyglucose positron emission tomography-computed tomography imaging of inferior vena cava tumor thrombus extending into the right atrium in a patient with cholangiocarcinoma treated with 90Y-Microspheres

We present a case of a 42-year-old male patient affected by unresectable, chemorefractory cholangiocarcinoma, with prior placement of biliary stent. Because of the absence of extrahepatic metastases, he was submitted to liver-direct therapy with 90Y-microspheres. 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) performed before the procedure showed intense tracer uptake in the hepatic lesion and along the biliary stent. The patient underwent radioembolization with 90Y-resin spheres (1.1 GBq). 18F-FDG PET-CT, acquired 6 weeks after the procedure, showed no response of the hepatic lesion and the appearance of an area of markedly increased uptake extending through the inferior vena cava into the right atrium, confirmed as extensive tumor thrombus at the enhanced multislice CT subsequently performed. 18F-FDG PET-CT proved to be a useful imaging tool not only for the evaluation of metabolic response but also for the early detection of extrahepatic progression after 90Y-radioembolization.

Yttrium-90 resin microspheres and their use in the treatment of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a severe and rapidly progressive hepatic tumor. Surgery is often impracticable due to locally advanced presentation. On the other hand, chemotherapy has demonstrated only limited effectiveness. For these reasons, liver-directed therapies have been successfully applied for treating ICC. In particular, radioembolization with Yttrium-90 (90Y)-labeled spheres has been reported to be a promising therapeutic approach for this neoplasia. Two commercial forms of 90Y-labeled spheres are available: glass (TheraSphere®) and resin (SIR-Spheres®) microspheres. The aim of the present paper is to review the existing literature on the use of the resin microspheres for the treatment of unresectable and chemorefractory ICC, focusing on the methodology, clinical applications and side effects.

90Y-radioembolization of hepatocellular carcinoma from a theranostic perspective: towards a personalized approach

Dear Sir, We have read with great interest the paper by Ho and colleagues describing the usefulness of dual tracer C-acetate and F-FDG PET-CT for the individualized dose calculation in patients affected by hepatocellular carcinoma submitted to treatment with Y-labeled glass microspheres [1]. We would like to congratulate the authors for this publication and thank them for focusing on a relevant question. The two tracers (i.e., C-acetate and F-FDG) were proposed as complementary biochemical probes to characterize hepatocellular carcinoma before undergoing the administration of Y-labeled glass microspheres, as the more aggressive hepatocellular lesions are generally F-FDG-avid, while the more differentiated ones can be visualized using C-acetate. A growing amount of scientific data concerning Yradioembolization in hepatocellular carcinoma has demonstrated its significant impact on outcomes [2]. To date, Yradioembolization represents a well-standardized procedure in which two commercially available devices (glass or resin microspheres) can be used. In this scenario, the study performed byHo and coworkers provides an opportunity to elaborate this innovative therapeutic approach from a theranostic perspective. The theranostic approach is a typical feature of nuclear medicine in which diagnostic imaging and therapy are often performed using the same molecules labeled with different radionuclides [3]. By extension, theranostics represent a combination of diagnostic and target therapy in order to achieve a personalized approach for every patient’s needs and characteristics. In this regard, the authors correlated the biological aggressiveness of hepatocellular carcinoma, determined by its affinity for F-FDG or C-acetate, with the dose delivered to the lesions, calculated on Y-PET-CT, and the response to Yradioembolization assessed with PET-CT. As a higher cut-off in tumor dose/response was found inF-FDG avid lesions in comparison with those detected byC-acetate, an individualized algorithm has been proposed for the prescription of Yglass microspheres. In this context, PET imaging with a specific molecular probe was used to define the most appropriate therapeutic approach. However, it has to be pointed out that acetate is labeled with C with a short 20-min half-life, limiting the use of this radiopharmaceutical only to PET-centers with on-site cyclotron. To overcome these drawbacks, Fcholine, a surrogate biomarker of membrane lipid synthesis, has been introduced for the PET imaging of welldifferentiated hepatocellular carcinoma, with a sensitivity ranging from 63 to 100% [4]. In our experience, the complementary use of F-FDG and F-choline may be particularly useful for the PET evaluation of plurifocal hepatocellular carcinoma before Y-radioembolization, as hepatic nodules within the same patient may present different grade of biological aggressiveness (Fig. 1). It should be noted that Ho et al. [1] defined the response to Y-treatment as a decrease in metabolic tumor volume calculated on the PET-CT performed 2 months after the procedure. Which the best time point and imaging method are to assess tumors following therapy with Y-microspheres is still under debate. Nevertheless, several published papers suggested that an early metabolic evaluation of hepatic tumors after locoregional treatments can be feasible as soon as 1 month after the procedure [5]. In a recent report from our group, the decrease in total lesion glycolysis (metabolic tumor volume × SUVmean) calculated on F-FDG PET at baseline and 1 month after Y-radioembolization resulted in a significant prognostic factor in patients affected by poorly differentiated * Luca Filippi l.filippi@ausl.latina.it

Phantom validation of quantitative Y-90 PET/CT-based dosimetry in liver radioembolization

BackgroundPET/CT has recently been shown to be a viable alternative to traditional post-infusion imaging methods providing good quality images of 90Y-laden microspheres after selective internal radiation therapy (SIRT). In the present paper, first we assessed the quantitative accuracy of 90Y-PET using an anthropomorphic phantom provided with lungs, liver, spine, and a cylindrical homemade lesion located into the hepatic compartment. Then, we explored the accuracy of different computational approaches on dose calculation, including (I) direct Monte Carlo radiation transport using Raydose, (II) Kernel convolution using Philips Stratos, (III) local deposition algorithm, (IV) Monte Carlo technique (MCNP) considering a uniform activity distribution, and (V) MIRD (Medical Internal Radiation Dose) analytical approach. Finally, calculated absorbed doses were compared with those obtained performing measurements with LiF:Mg,Cu,P TLD chips in a liquid environment.ResultsOur results indicate that despite 90Y-PET being likely to provide high-resolution images, the 90Y low branch ratio, along with other image-degrading factors, may produce non-uniform activity maps, even in the presence of uniform activity. A systematic underestimation of the recovered activity, both for the tumor insert and for the liver background, was found. This is particularly true if no partial volume correction is applied through recovery coefficients. All dose algorithms performed well, the worst case scenario providing an agreement between absorbed dose evaluations within 20%. Average absorbed doses determined with the local deposition method are in excellent agreement with those obtained using the MIRD and the kernel-convolution dose calculation approach.Finally, absorbed dose assessed with MC codes are in good agreement with those obtained using TLD in liquid solution, thus confirming the soundness of both calculation approaches. This is especially true for Raydose, which provided an absorbed dose value within 3% of the measured dose, well within the stated uncertainties.ConclusionsPatient-specific dosimetry is possible even in a scenario with low true coincidences and high random fraction, as in 90Y–PET imaging, granted that accurate absolute PET calibration is performed and acquisition times are sufficiently long. Despite Monte Carlo calculations seeming to outperform all dose estimation algorithms, our data provide a strong argument for encouraging the use of the local deposition algorithm for routine 90Y dosimetry based on PET/CT imaging, due to its simplicity of implementation.