[F-18]-fluorodeoxyglucose PET-CT of the normal prostate gland

Objective  We determined the glucose metabolism and computed tomographic (CT) density of the normal prostate gland in relation to age and prostate size on [F-18] fluorodeoxyglucose positron emission tomography (PET)-CT. Methods  We determined the CT density (Hounsfield Units, HU) and glucose metabolism (standardized uptake value, SUV) of the normal prostate in 145 men (age range 22–97 years) on PET-CT scans which were performed for indications unrelated to prostate pathology. Correlations among SUV, HU, prostate size, and age were calculated using Pearson’s correlation coefficients, scatter plots, and linear regression trend lines. The SUV and HU values were also compared among different primary cancer types using the Kruskal-Wallis test. Results  The population average and range of the normal prostate size were 4.3 ± 0.5 cm (mean ± SD) and 2.9–5.5 cm, respectively. The population average of mean and maximum CT densities was 36.0 ± 5.1 HU (range 23-57) and 91.7 ± 20.1 HU (range 62-211), respectively. The population average of mean and maximum SUV was 1.3 ± 0.4 (range 0.1–2.7) and 1.6 ± 0.4 (range 1.1–3.7), respectively. Mean SUV tended to decrease as the prostate size increased (r = −0.16, P = 0.058). Higher mean HU was correlated with higher mean SUV (r = 0.18, P = 0.033). The strongest association was observed between age and prostate size. The prostate gets larger as age increases (r = 0.32, P < 0.001). Prostate mean SUV, max SUV, mean HU, and max HU were not significantly different among different types of primary cancers. Conclusions  Although the normal prostate size increases with age, it does not significantly affect the gland’s metabolism and CT density, and therefore age-correction of these parameters may be unnecessary.     

Transpulmonary chemoembolization (TPCE) as a treatment for unresectable lung metastases

To evaluate tumor response after treating unresectable lung metastases with transpulmonary chemoembolization (TPCE) in palliative intention. From 2001 to 2005, 52 patients (mean: 59.8 years; 32 males/20 females) suffering from 106 unresectable lung metastases (mean:6 metastases/patient; range,1–21) were treated with 2–10 TPCE-sessions (mean: 3.3 sessions/patient). Metastases originated from primaries, including colorectal carcinoma (n = 20), breast cancer (n = 6), renal cellular carcinoma (n = 5), thyroid cancer (n = 4), cholangiocellular carcinoma (n = 2), leiomyosarcoma (n = 2), and others (n = 13). Tumor-feeding pulmonary arteries were selectively probed after puncturing the femoral vein, and administering 10 ml lipiodol, mitomycin C, and microspheres (Spherex) each via balloon catheter over pulmonary approach. During therapy, follow-up was accomplished at 4-week intervals using unenhanced and contrast-enhanced CT. After sequential therapy, follow-up was performed every 3 months for a period of 6 months up to 2.25 years. All patients tolerated the treatments well without major side effects or complications. In 24% (n = 13) moderate to high lipiodol uptake was found, while 75% (n = 39) of the tumors showed a low uptake. According to the RECIST criteria, “partial response” was achieved in 16 cases, “stable disease” in 11 cases, and “progressive disease” in 25 cases [mean survival: 17 months/median: 21.1 months (Kaplan-Meyer)]. According to these findings, TPCE is a well-tolerated procedure for palliative treatment of unresectable lung metastases.     

<Superscript>99m</Superscript>Tc-HYNIC octreotide in neuroblastoma

Disease status assessment of neuroblastoma patients requires computed tomography (or magnetic resonance imaging), bone scan, metaiodobenzylguanidine (MIBG) scan, bone marrow tests, and urine catecholamine measurements. There is no clinical experience concerning the evaluation of these patients by means of technetium-99m (^99mTc)-somatostatin analog scintigraphy. Furthermore, these radiopharmaceuticals are promising imaging agents owing to their lower cost, availability, dosimetry, and ease of preparation. An 8-year-old boy already diagnosed with stage-IV neuroblastoma received chemotherapy. In the follow-up, after obtaining the parents’ informed consent, iodin 131 (¹³¹I)-MIBG and ^99mTc-6-hydrazinopyridine-3-carboxylic acid (HYNIC)-octreotide scans were done on separate days to evaluate tumor extension. Even as the ¹³¹I-IBG scan showed mild diffuse uptake in the projection of both lung hili, the ^99mTc-HYNIC-octreotide scan showed multiple axial and appendicular bone uptakes and paravertebral, abdominal, mediastinal, and supraclavicular ganglionar uptakes. The ^99mTc-HYNIC-octreotide showed much more lesion extension than the ¹³¹I-MIBG. Therefore, ^99mTc-HYNIC-octreotide may be a promising radiopharmaceutical for the evaluation of neuroblastoma patients. This finding justifies the pre liminary evaluation of this tracer in the context of a clinical trial.     

Comparison of 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine-enhanced MRI in 471 patients with known or suspected renal lesions: results of a multicenter, single-blind, interindividual, randomized clinical phase III trial

The purpose of this phase III clinical trial was to compare two different extracellular contrast agents, 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine, for magnetic resonance imaging (MRI) in patients with known or suspected focal renal lesions. Using a multicenter, single-blind, interindividual, randomized study design, both contrast agents were compared in a total of 471 patients regarding their diagnostic accuracy, sensitivity, and specificity to correctly classify focal lesions of the kidney. To test for noninferiority the diagnostic accuracy rates for both contrast agents were compared with CT results based on a blinded reading. The average diagnostic accuracy across the three blinded readers (‘average reader’) was 83.7% for gadobutrol and 87.3% for gadopentate dimeglumine. The increase in accuracy from precontrast to combined precontrast and postcontrast MRI was 8.0% for gadobutrol and 6.9% for gadopentate dimeglumine. Sensitivity of the average reader was 85.2% for gadobutrol and 88.7% for gadopentate dimeglumine. Specificity of the average reader was 82.1% for gadobutrol and 86.1% for gadopentate dimeglumine. In conclusion, this study documents evidence for the noninferiority of a single i.v. bolus injection of 1.0 M gadobutrol compared with 0.5 M gadopentate dimeglumine in the diagnostic assessment of renal lesions with CE-MRI.

Arterio-Ureteric Fistula Following Iliac Angioplasty

Arterio-ureteric fistulae are rare but can be associated with significant morbidity and mortality. We describe a novel case in which an arterio-ureteric fistula occurred as a complication following external iliac artery angioplasty and stenting, in a patient who had undergone previous pelvic surgery, radiotherapy, ureteric stenting, and urinary diversion surgery. Prompt recognition enabled successful endovascular management using a covered stent.     

Incremental prognostic value of <Superscript>99m</Superscript>Tc-tetrofosmin myocardial SPECT after percutaneous coronary intervention

Objective  Percutaneous transluminal coronary angioplasty is a well-established therapeutic method in selected patients with coronary artery disease. The aim of this study was to assess the incremental prognostic value of technetium-99m (^99mTc)-tetrofosmin myocardial gated-single- photon emission computed tomography (SPECT) in asymptomatic patients after coronary artery stenting. Methods  A total of 246 consecutive patients (aged 55.5 ± 8.2 years, 182 men) participated in the study with a median follow-up of 9.5 years (interquartile ra 5.8–10.5 years). All patients underwent exercise gated-SPECT myocardial imaging within 5–7 months. Myocardial scintigrams were performed using 99mTctetrofosmin, and were evaluated calculating the summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) indexes. Cardiovascular death and non-fatal myocardial infarction were considered as hard cardiac events, and late revascularization (>3 months after myocardial SPECT) procedures as soft events. Receiver-operating characteristic (ROC) analysis was used to test the prognostic ability of SSS and SDS for cardiac events. Cox proportional hazards models were used to evaluate the incremental value of SPECT variables. Results  Cardiac death occurred in 12 (4.9%) patients and non-fatal myocardial infarction in 20 (8.1%) patients. In addition, 60 (24.4%) patients underwent a late revascularization procedure. Using ROC analysis the optimal cut-offs of SSS (AUC = 0.94; 95% CI 0.92–0.97) and SDS (AUC = 0. 76; 95% CI 0.70–0.82) for the prediction of cardiac events were 10 and 1.7, respectively. Multiple Cox regression analyses revealed that SSS > 10 (HR = 24.2; 95% CI 7.44–78.79) and SDS > 1.7 (HR = 2.72; 95% CI 1.23–6.00) provided incremental prognostic value over clinical and exercise test data for the composite end points of any cardiac event. Conclusions   ^99mTc-tetrofosmin myocardial gated- SPECT, performed 6 months post-percutaneous coronary intervention (PCI), provides incremental prognostic information for the prediction of cardiac events in asymptomatic patients after PCI.     

CT-guided percutaneous laser photocoagulation of osteoid osteomas of the hands and feet

Percutaneous local ablation of osteoid osteoma has largely replaced surgery, except in the small bones of the hands and feet. The objective of this study was to describe the technical specificities and results of computed tomography (CT)-guided percutaneous laser photocoagulation in 15 patients with osteoid osteomas of the hands and feet. We retrospectively examined the medical charts of the 15 patients who were treated with CT-guided percutaneous laser photocoagulation therapy at our institution between 1994 and 2004. The 15 patients had a mean age of 24.33 years. None of them had received any prior surgical or percutaneous treatment for the osteoid osteoma. The follow-up period was 24 to 96 months (mean, 49.93). The pain resolved completely within 1 week. Fourteen patients remained symptom-free throughout the follow-up period; the remaining patient experienced a recurrence of pain after 24 months, underwent a second laser photocoagulation procedure, and was symptom-free at last follow-up 45 months later. No adverse events related to the procedure or to the location of the tumor in the hand or the foot were recorded. CT-guided percutaneous laser photocoagulation is an alternative to surgery for the treatment of osteoid osteomas of the hands and feet.     

Occult acetabulum fracture. A case report

Acetabular fractures that are radiographically occult are associated with insufficiency fractures, stress fractures, and fractures secondary to steroid-induced osteoporosis, usually affecting older patients after low-energy trauma. Occult acetabulum fractures in young patients are extremely rare. We discuss herein a case of an occult acetabulum fracture after high-energy trauma, in a young patient. This case illustrates the need for further diagnostic studies such as computed tomography, magnetic resonance imaging, or bone scanning when, despite negative radiographic findings, groin pain is persistent.     

Initial clinical results for breath-hold CT-based processing of respiratory-gated PET acquisitions

Purpose  Respiratory motion causes uptake in positron emission tomography (PET) images of chest structures to spread out and misregister with the CT images. This misregistration can alter the attenuation correction and thus the quantisation of PET images. In this paper, we present the first clinical results for a respiratory-gated PET (RG-PET) processing method based on a single breath-hold CT (BH-CT) acquisition, which seeks to improve diagnostic accuracy via better PET-to-CT co-registration. We refer to this method as “CT-based” RG-PET processing. Methods  Thirteen lesions were studied. Patients underwent a standard clinical PET protocol and then the CT-based protocol, which consists of a 10-min List Mode RG-PET acquisition, followed by a shallow end-expiration BH-CT. The respective performances of the CT-based and clinical PET methods were evaluated by comparing the distances between the lesions’ centroids on PET and CT images. SUV_MAX and volume variations were also investigated. Results  The CT-based method showed significantly lower (p = 0.027) centroid distances (mean change relative to the clinical method = −49%; range = −100% to 0%). This led to higher SUV_MAX (mean change = +33%; range = −4% to 69%). Lesion volumes were significantly lower (p = 0.022) in CT-based PET volumes (mean change = −39%: range = −74% to −1%) compared with clinical ones. Conclusions  A CT-based RG-PET processing method can be implemented in clinical practice with a small increase in radiation exposure. It improves PET-CT co-registration of lung lesions and should lead to more accurate attenuation correction and thus SUV measurement.