The reconstruction algorithm used for [68Ga]PSMA-HBED-CC PET/CT reconstruction significantly influences the number of detected lymph node metastases and coeliac ganglia.

PURPOSE: To investigate whether the numbers of lymph node metastases and coeliac ganglia delineated on [68Ga]PSMA-HBED-CC PET/CT scans differ among datasets generated using different reconstruction algorithms. METHODS: Data were constructed using the BLOB-OS-TF, BLOB-OS and 3D-RAMLA algorithms. All reconstructions were assessed by two nuclear medicine physicians for the number of pelvic/paraaortal lymph node metastases as well the number of coeliac ganglia. Standardized uptake values (SUV) were also calculated in different regions. RESULTS: At least one [68Ga]PSMA-HBED-CC PET/CT-positive pelvic or paraaortal lymph node metastasis was found in 49 and 35 patients using the BLOB-OS-TF algorithm, in 42 and 33 patients using the BLOB-OS algorithm, and in 41 and 31 patients using the 3D-RAMLA algorithm, respectively, and a positive ganglion was found in 92, 59 and 24 of 100 patients using the three algorithms, respectively. Quantitatively, the SUVmean and SUVmax were significantly higher with the BLOB-OS algorithm than with either the BLOB-OS-TF or the 3D-RAMLA algorithm in all measured regions (p < 0.001 for all comparisons). The differences between the SUVs with the BLOB-OS-TF- and 3D-RAMLA algorithms were not significant in the aorta (SUVmean, p = 0.93; SUVmax, p = 0.97) but were significant in all other regions (p < 0.001 in all cases). The SUVmean ganglion/gluteus ratio was significantly higher with the BLOB-OS-TF algorithm than with either the BLOB-OS or the 3D-RAMLA algorithm and was significantly higher with the BLOB-OS than with the 3D-RAMLA algorithm (p < 0.001 in all cases). CONCLUSION: The results of [68Ga]PSMA-HBED-CC PET/CT are affected by the reconstruction algorithm used. The highest number of lesions and physiological structures will be visualized using a modern algorithm employing time-of-flight information.

Detection of recurrent prostate cancer lesions before salvage lymphadenectomy is more accurate with (68)Ga-PSMA-HBED-CC than with (18)F-Fluoroethylcholine PET/CT.

AIM: [(68)Ga]PSMA-HBED-CC ((68)Ga-PSMA) is a novel and promising tracer for highly sensitive combined integrated positron emission tomography and X-ray computed tomography (PET/CT) diagnosis of recurrent prostate cancer (PCA). Our aim was to assess the sensitivity, specificity, positive and negative predictive value (PPV/NPV), and accuracy per lesion, as well as the positive predictive value per patient of (68)Ga-PSMA PET/CT using post-lymphadenectomy histology as a standard, and to compare these values to those obtained in a patient collective scanned using (18)F-Fluoroethylcholine ((18)FEC) PET/CT. METHODS: Thirty eight patients had (18)FEC and 28 patients had (68)Ga-PSMA. We performed a pelvic and/or retroperitoneal lymphadenectomy, if necessary supplemented by resection of locally recurrent lesions in accordance with imaging results. RESULTS: In 30/38 (18)FEC and 23/28 (68)Ga-PSMA patients ≥1 focus of PCA was identified in postsurgical histology, leading to a per-patient PPV of 78.9 % for (18)FEC and 82.1 % for (68)Ga-PSMA. In (18)FEC and (68)Ga-PSMA patients, a total of 378 and 308 lymph nodes and local lesions were removed, respectively. For (18)FEC and (68)for Ga-PSMA, the respective sensitivity (95 % confidence interval) was 71.2 % (64.5-79.6 %) and 86.9 % (75.8-94.2 %), specificity was 86.9 % (82.3-90.6 % ) and 93.1 % (89.2-95.9 %), PPV was 67.3 % (57.7-75.9 %) and 75.7 % (64.0-98.5 %), NPV was 88.8 % (84.4-92.3 %) and 96.6 % (93.5-98.5 %), and accuracy was 82.5 % (78.3-86.8 %) and 91.9 % (88.7 %-95.1 %). CONCLUSION: In the present series Ga-PSMA PET/CT shows a better performance than FEC PET/CT with a significantly higher NPV and accuracy for the detection of locoregional recurrent and/or metastatic lesions prior to salvage lymphadenectomy.

Extent of disease in recurrent prostate cancer determined by [(68)Ga]PSMA-HBED-CC PET/CT in relation to PSA levels, PSA doubling time and Gleason score.

PURPOSE: To examine the relationship between the extent of disease determined by [(68)Ga]PSMA-HBED-CC-PET/CT and the important clinical measures prostate-specific antigen (PSA), PSA doubling time (PSAdt) and Gleason score. METHODS: We retrospectively studied the first 155 patients with recurrent prostate cancer (PCA) referred to our university hospital for [(68)Ga]PSMA-HBED-CC PET/CT. RESULTS: PET/CT was positive in 44%, 79% and 89% of patients with PSA levels of ≤1, 1-2 and ≥2 ng/ml, respectively. Patients with high PSA levels showed higher rates of local prostate tumours (p < 0.001), and extrapelvic lymph node (p = 0.037) and bone metastases (p = 0.013). A shorter PSAdt was significantly associated with pelvic lymph node (p = 0.026), extrapelvic lymph node (p = 0.001), bone (p < 0.001) and visceral (p = 0.041) metastases. A high Gleason score was associated with more frequent pelvic lymph node metastases (p = 0.039). In multivariate analysis, both PSA and PSAdt were independent determinants of scan positivity and of extrapelvic lymph node metastases. PSAdt was the only independent marker of bone metastases (p = 0.001). Of 20 patients with a PSAdt <6 months and a PSA ≥2 ng/ml, 19 (95%) had a positive scan and 12 (60%) had M1a disease. Of 14 patients with PSA <1 ng/ml and PSAdt >6 months, only 5 (36%) had a positive scan and 1 (7%) had M1a disease. CONCLUSION: [(68)Ga]PSMA-HBED-CC PET/CT will identify PCA lesions even in patients with very low PSA levels. Higher PSA levels and shorter PSAdt are independently associated with scan positivity and extrapelvic metastases, and can be used for patient selection for [(68)Ga]PSMA-HBED-CC PET/CT.

[(68)Ga]PSMA-HBED uptake mimicking lymph node metastasis in coeliac ganglia: an important pitfall in clinical practice.

PURPOSE: To determine the frequency of seemingly pathological retroperitoneal uptake in the location of the coeliac ganglia in patients undergoing [(68)Ga]PSMA-HBED PET/CT. METHODS: The study included 85 men with prostate cancer referred for [(68)Ga]PSMA-HBED PET/CT. The PET/CT scans were evaluated for the local finding in the prostate and the presence of lymph node metastases, distant metastases and coeliac ganglia. The corresponding standardized uptake values (SUV) were determined. SUVmax to background uptake (gluteal muscle SUVmean) ratios were calculated for the ganglia and lymph node metastases. Immunohistochemistry was performed on the ganglia. RESULTS: In 76 of the 85 patients (89.4%) at least one ganglion with tracer uptake was found. For the ganglia, SUVmax and SUVmax to background SUVmean ratios were 2.97 ± 0.88 and 7.98 ± 2.84 (range 1.57-6.38 and 2.83-30.6), respectively, and 82.8% of all ganglia showed an uptake ratio of >5.0. For lymph node metastases, SUVmax and SUVmax to background SUVmean ratios were 8.5 ± 7.0 and 23.31 ± 22.23 (range 2.06-35.9 and 5.25-115.8), respectively. In 35 patients (41.2%), no lymph node metastases were found but tracer uptake was seen in the ganglia. Immunohistochemistry confirmed strong PSMA expression in the ganglia. CONCLUSION: Coeliac ganglia show a relevant [(68)Ga]PSMA-HBED uptake in most patients and may mimic lymph node metastases.

Thyroid nodules with indeterminate cytology: molecular imaging with 99mTc-methoxyisobutylisonitrile (MIBI) is more cost-effective than the Afirma gene expression classifier.

PURPOSE: To compare the cost-effectiveness of (99m)Tc-methoxyisobutylisonitrile (MIBI) thyroid scintigraphy and the Afirma gene expression classifier for the assessment of cytologically indeterminate thyroid nodules. METHODS: A decision tree model was used. Costs were calculated from the perspective of the German health insurance system. The robustness of the results was assessed with probabilistic sensitivity analyses using a Monte Carlo simulation. RESULTS: Life expectancy was 34.3 years (estimated costs per patient €1,459 - €2,224) for the MIBI scan and 34.1 years (estimated costs €3,560 - €4,071) for the molecular test. These results were confirmed by the Monte Carlo simulation. CONCLUSION: MIBI thyroid scintigraphy is more cost-effective than the gene expression classifier.

A low molecular weight zinc2+-dipicolylamine-based probe detects apoptosis during tumour treatment better than an annexin V-based probe.

OBJECTIVES: Molecular imaging of apoptosis is frequently discussed for monitoring cancer therapies. Here, we compare the low molecular weight phosphatidylserine-targeting ligand zinc2+-dipicolylamine (Zn2+-DPA) with the established but reasonably larger protein annexin V. METHODS: Molecular apoptosis imaging with the fluorescently labelled probes annexin V (750 nm, 36 kDa) and Zn2+-DPA (794 nm, 1.84 kDa) was performed in tumour-bearing mice (A431). Three animal groups were investigated: untreated controls and treated tumours after 1 or 4 days of anti-angiogenic therapy (SU11248). Additionally, µPET with 18 F-FDG was performed. Imaging data were displayed as tumour-to-muscle ratio (TMR) and validated by quantitative immunohistochemistry. RESULTS: Compared with untreated control tumours, TUNEL staining indicated significant apoptosis after 1 day (P < 0.05) and 4 days (P < 0.01) of treatment. Concordantly, Zn2+-DPA uptake increased significantly after 1 day (P < 0.05) and 4 days (P < 0.01). Surprisingly, annexin V failed to detect significant differences between control and treated animals. Contrary to the increasing uptake of Zn2+-DPA, 18 F-FDG tumour uptake decreased significantly at days 1 (P < 0.05) and 4 (P < 0.01). CONCLUSIONS: Increase in apoptosis during anti-angiogenic therapy was detected significantly better with the low molecular weight probe Zn2+-DPA than with the annexin V-based probe. Additionally, significant treatment effects were detectable as early using Zn2+-DPA as with measurements of the glucose metabolism using 18 F-FDG. KEY POINTS: • The detection of apoptosis by non-invasive imaging is important in oncology. • A new low molecular weight probe Zn2+-DPA shows promise in depicting anti-angiogenic effects. • The small Zn2+-DPA ligand appears well suited for monitoring therapy. • Treatment effects are detectable just as early with Zn2+-DPA as with 18F-FDG.

Diagnosis of pulmonary embolism: conventional ventilation/perfusion SPECT is superior to the combination of perfusion SPECT and nonenhanced CT.

BACKGROUND: Ventilation/perfusion single-emission photon CT (V/P-SPECT) is widely used to detect pulmonary embolism (PE). Any pathological deficit on P-SPECT with a corresponding unremarkable V-SPECT is considered an embolism. This means that a deficit on P-SPECT with a corresponding deficit on the ventilation scan correlates with other lung pathologies such as pneumonia, bullous emphysema or tumor. In principle, it is possible to identify any of these lung pathologies on nonenhanced chest CT and so this technique has the potential to replace V-SPECT in the diagnosis of PE. Today, SPECT/CT hybrid imaging systems are increasingly applied in clinical routines. OBJECTIVES: We investigated whether embolism can be diagnosed using a combined P-SPECT/CT hybrid imaging approach without V-SPECT. METHODS: Ninety-three patients with clinically suspected embolism were investigated with standard V/P-SPECT and a nonenhanced CT scan on a combined SPECT/CT system. A diagnosis of embolism was based on V/P-SPECT (gold standard). P-SPECT/CT datasets were blinded and analyzed without any knowledge of the V-SPECT data. The accuracy of P-SPECT/CT was compared to the gold standard. RESULTS: Embolism was diagnosed in 24/93 patients using V/P-SPECT. In total, 57 lung lobes were affected. P-SPECT/CT significantly (p < 0.01) overdiagnosed embolism in nonaffected patients. In total, 36 cases with 88 affected lung lobes were shown. The sensitivity was 95.8%, the specificity 82.6%, the false-negative rate 4.2% and the false-positive rate 17.3%. CONCLUSIONS: Our results demonstrate that a nonenhanced CT scan in a novel hybrid imaging system cannot replace V-SPECT in the scintigraphy-based diagnosis of PE. V-SPECT increases specificity and reduces the number of false-positive results when compared to 'perfusion-only' SPECT/CT.

Phantom studies and clinical application of high resolution, image reconstruction using (18)F-fluoromethylcholine PET/CT for prostate cancer.

The aim of this study is to evaluate the impact of a high resolution (HR) image reconstruction with a voxel size of 2mm in comparison to the most routinely used standard reconstruction with 4mm voxels in patients suffering from prostate cancer having undergone (18)F-methylcholine PET/CT. Phantom studies were performed using a Jaszczak phantom and a custom made phantom containing small hot lesions (size 2-10mm). Clinical evaluation was performed on PET/CT scans of 50 patients. Images were reconstructed with 4mm and 2mm voxel size and analyzed quantitatively using AMIDE and MATLAB. Clinical images were judged by two observers concerning TNM staging, image quality and the correlation of PET and CT data. Phantom studies revealed increased SUVmean and SUVmax values in the HR images (P<0.01). The lower detection limit was approximately 3mm in the HR and 4-5mm in the conventional images. Lower FWHM values were found in the HR images. No significant difference was found concerning the image quality and the correlation of PET and CT (each P>0.5). For both reconstructions, a comparable total amount of lesions was reported (P>0.5) with no impact on the TNM staging. In conclusion, the HR PET reconstruction provides semi-quantitative advantages in the sense of an improved lower detection limit and increased semi-quantitative tumour-to-background ratios. In the setting of choline PET/CT for prostate cancer the high resolution reconstruction could be implemented clinically as there are no relevant qualitative differences between this and the conventional image resolution in terms of image quality, assessment confidence and lesion identification rate.

Contrast medium injection protocol adjusted for body surface area in combined PET/CT.

OBJECTIVES: To evaluate the effect of contrast medium dose adjustment for body surface area (BSA) compared with a fixed-dose protocol in combined positron emission tomography (PET) and computed tomography (CT) (PET/CT). METHODS: One hundred and twenty patients were prospectively included for (18)F-2-deoxy-fluor-glucose ((18)F-FDG)-PET/CT consisting of a non-enhanced and a venous contrast-enhanced CT, both used for PET attenuation correction. The first 60 consecutive patients received a fixed 148-ml contrast medium dose. The second 60 patients received a dose that was based on their calculated BSA. Mean and maximum standardised FDG uptake (SUVmean and SUVmax) and contrast enhancement (HU) were measured at multiple anatomical sites and PET reconstructions were evaluated visually for image quality. RESULTS: A decrease in the variance of contrast enhancement in the BSA group compared with the fixed-dose group was seen at all anatomical sites. Comparison of tracer uptake SUVmean and SUVmax between the fixed and the BSA group revealed no significant differences at all anatomical sites (all P > 0.05). Comparison of the overall image quality scores between the fixed and the BSA group showed no significant difference (P = 0.753). CONCLUSIONS: BSA adjustment results in increased interpatient homogeneity of contrast enhancement without affecting PET values. In combined PET/CT, a BSA adjusted contrast medium protocol should be used preferably. KEY POINTS: • Intravenous contrast medium is essential for many applications of PET/CT • Body surface area adjustment of contrast medium helps standardise contrast enhancement • Underdosing or overdosing of contrast medium will be reduced • PET image quality is not influenced • BSA adjusted contrast medium protocol should be used preferably in combined PET/CT.

Simultaneous dual-isotope SPECT/CT with (99m)Tc- and (111)In-labelled albumin microspheres in treatment planning for SIRT.

OBJECTIVES: To investigate simultaneous dual-isotope SPECT/CT with two differently radioisotope-labelled albumin-microsphere fractions for treatment planning of hepatic radioembolisation. METHODS: In addition to (99m)Technetium-labelled albumin microspheres (commercially available), we performed labelling with (111)Indium. Binding stability of (111)Indium-labelled microspheres was tested in vitro and in vivo in mice. Simultaneous dual-isotope SPECT/CT imaging was validated in an anthropomorphic torso phantom; subsequently, dual-isotope SPECT/CT was performed under in-vivo conditions in pigs (n = 3) that underwent transarterial injection of (99m)Technetium- and (111)Indium-labelled microspheres in the liver (right and left hepatic artery, respectively), in both kidneys and in the gluteal musculature. In total, n = 18 transarterial injections were performed. RESULTS: In-vitro testing and in-vivo studies in mice documented high binding stability for both (99m)Technetium-labelled and (111)Indium-labelled microsphere fractions. In phantom studies, simultaneous dual-isotope SPECT/CT enabled reliable separation of both isotopes. In pigs, the identified deposition of both isotopes could be accurately matched with intended injection targets (100 %, 18/18 intended injection sites). Furthermore, an incidental deposition of (99m)Technetium-labelled microspheres in the stomach could be correlated to the test injection into a right hepatic artery. CONCLUSION: Simultaneous dual-isotope SPECT/CT after transarterial injection with (99m)Technetium- and (111)Indium-labelled microspheres is feasible. Thus, it may offer additional, valuable information compared to single (99m)Technetium-labelled albumin examinations. KEY POINTS: • Simultaneous dual-isotope SPECT/CT with (111) In- and (99m) Tc-labelled albumin microspheres is feasible. • Differentiation of two microsphere fractions after transarterial injection is possible. • The origin of an extra-hepatic microsphere deposition can be correlated to the corresponding artery. • This technique could reduce the setup time for selective internal radiation treatment.

Identification of the iodine concentration that yields the highest intravascular enhancement in MDCT angiography.

OBJECTIVE: The objective of our study was to identify the iodine concentration that yields the highest intravascular contrast enhancement in MDCT angiography by intraindividual comparison in an animal model. MATERIALS AND METHODS: Six pigs underwent repeated chest MDCT examinations under standardized conditions using the same contrast medium (iopromide) with different iodine concentrations (150, 240, 300, and 370 mg I/mL). The contrast injection protocol was adapted to ensure an identical iodine delivery rate of 1.5 g I/s and the same total iodine dose of 300 mg/kg of body weight for all studies. Dynamic CT scans were acquired at the levels of the pulmonary artery and the ascending and descending aorta. Pulmonary and aortic peak enhancement values as well as time to peak (TTP) were calculated from time-enhancement curves. RESULTS: Pulmonary and aortic peak contrast enhancement values were significantly higher with the 240 and 300 mg I/mL contrast media than the 150 and 370 mg I/mL contrast media (e.g., ascending aorta: 240 vs 150, p = 0.0070; 300 vs 150, p = 0.0096; 240 vs 370, p = 0.0262; 300 vs 370, p = 0.0079). TTP values tended to be lower for the 150 mg I/mL contrast medium than for the contrast media with higher iodine concentrations. CONCLUSION: Comparison of contrast media with iodine concentrations ranging from 150 to 370 mg I/mL showed that contrast enhancement was significantly improved with the use of 240 and 300 mg I/mL contrast media given a fixed identical iodine delivery and normalized total iodine load in a porcine model. Contrast media with a moderate iodine concentration are most suitable for obtaining the highest intravascular contrast enhancement in CT angiography.

PET/CT in lung cancer: Influence of contrast medium on quantitative and clinical assessment.

OBJECTIVES: To evaluate the influence of intravenous contrast medium and different contrast medium phases on attenuation correction, PET image quality and clinical staging in combined PET/CT in patients with a suspicion of lung cancer. METHODS: Sixty patients with a suspicion of lung cancer were prospectively enrolled for combined (18)F-FDG-PET/CT examination. PET images were reconstructed with non-enhanced and arterial and venous phase contrast CT. Maximum and mean standardised uptake values (SUVmax and SUVmean) and contrast enhancement (HU) were determined in the subclavian vein, ascending aorta, abdominal aorta, inferior vena cava, portal vein, liver and kidney and lung tumour. PET data were evaluated visually for clinical staging and image quality. RESULTS: SUVmax was significantly increased between contrast and non-contrast PET/CT at all anatomic sites (all P < 0.001). SUVmax was significantly increased for arterial PET/CT compared to venous PET/CT in the arteries (all P < 0.001). Venous PET/CT resulted in significantly higher SUVmax values compared to arterial PET/CT in the parenchymatous organs (all P < 0.05). Visual clinical evaluation of malignant lesions showed no differences between contrast and non-contrast PET/CT (P = 1.0). CONCLUSIONS: Contrast enhanced CT is suitable for attenuation correction in combined PET/CT in lung cancer; it affects neither the clinical assessment nor image quality of the PET images. KEY POINTS : • Positron emission tomography combined with computed tomography is now a mainstream investigation • There has been debate about whether CT contrast agents affect PET results • Contrast-enhanced CT is satisfactory for attenuation correction in lung cancer PET/CT • Multiphase CT does not affect PET; additional unenhanced CT is unnecessary • For quantitative follow-up PET analysis, an identical PET/CT protocol is required.

Development and validation of an intrinsic landmark-based gating protocol applicable for functional and molecular ultrasound imaging.

OBJECTIVES: To implement a retrospective intrinsic landmark-based (ILB) gating protocol for contrast-enhanced ultrasound (CEUS) and to compare its efficiency to non-gated, manually gated and extrinsically gated CEUS. METHODS: CEUS of the liver was performed in healthy mice (n = 5) and in NEMO knockout mice with dysplastic livers (n = 5). In healthy animals, first-pass kinetics of non-specific microbubbles was recorded. Knockout mice were analysed regarding retention of VEGFR2-specific microbubbles. For retrospective gating, a landmark which showed respiratory movement was encircled as a region of interest (ROI). During inspiration, the signal intensity within the ROI altered, which served as gating signal. To evaluate the accuracy, non-gated, extrinsically gated and ILB-gated time-intensity curves were created. For each curve, descriptive parameters were calculated and compared to the gold standard (manual frame-by-frame gating). RESULTS: No significant differences in the variation of ILB- and extrinsically gated time-intensity curves from the gold standard were observed. Non-gated data showed significantly higher variations. Also the variation of molecular ultrasound data was significantly lower for ILB-gated compared to non-gated data. CONCLUSION: ILB gating is a robust and easy method to improve data accuracy in functional and molecular ultrasound liver imaging. This technique can presumably be translated to contrast-enhanced ultrasound examinations in humans. KEY POINTS: • Quantitative analysis of the uptake of contrast agents during ultrasound is complex. • Intrinsic landmark-based gating (ILB) offers a simple implementable method for motion correction. • Results using ILB-gating are comparable to extrinsic gating using external biomonitoring devices. • Functional and molecular imaging of mobile organs will benefit from ILB gating.

Differences in predicted and actually absorbed doses in peptide receptor radionuclide therapy.

PURPOSE: An important assumption in dosimetry prior to radionuclide therapy is the equivalence of pretherapeutic and therapeutic biodistribution. In this study the authors investigate if this assumption is justified in sst2-receptor targeting peptide therapy, as unequal amounts of peptide and different peptides for pretherapeutic measurements and therapy are commonly used. METHODS: Physiologically based pharmacokinetic models were developed. Gamma camera and serum measurements of ten patients with metastasizing neuroendocrine tumors were conducted using (111)In-DTPAOC. The most suitable model was selected using the corrected Akaike information criterion. Based on that model and the estimated individual parameters, predicted and measured (90)Y-DOTATATE excretions during therapy were compared. The residence times for the pretherapeutic (measured) and therapeutic scenarios (simulated) were calculated. RESULTS: Predicted and measured therapeutic excretion differed in three patients by 10%, 31%, and 7%. The measured pretherapeutic and therapeutic excretion differed by 53%, 56%, and 52%. The simulated therapeutic residence times of kidney and tumor were 3.1 ± 0.6 and 2.5 ± 1.2 fold higher than the measured pretherapeutic ones. CONCLUSIONS: To avoid the introduction of unnecessary inaccuracy in dosimetry, using the same substance along with the same amount for pretherapeutic measurements and therapy is recommended.

Severe gastric variceal haemorrhage due to splenic artery thrombosis and consecutive arterial bypass.

BACKGROUND: Upper gastrointestinal haemorrhage is mainly caused by ulcers. Gastric varicosis due to portal hypertension can also be held responsible for upper gastrointestinal bleeding. Portal hypertension causes the development of a collateral circulation from the portal to the caval venous system resulting in development of oesophageal and gastric fundus varices. Those may also be held responsible for upper gastrointestinal haemorrhage. CASE PRESENTATION: In this study, we describe the case of a 69-year-old male with recurrent severe upper gastrointestinal bleeding caused by arterial submucosal collaterals due to idiopathic splenic artery thrombosis. The diagnosis was secured using endoscopic duplex ultrasound and angiography. The patient was successfully treated with a laparoscopic splenectomy and complete dissection of the short gastric arteries, resulting in the collapse of the submucosal arteries in the gastric wall. Follow-up gastroscopy was performed on the 12th postoperative week and showed no signs of bleeding and a significant reduction in the arterial blood flow within the gastric wall. Subsequent follow-up after 6 months also showed no further gastrointestinal bleeding as well as subjective good quality of life for the patient. CONCLUSION: Submucosal arterial collaterals must be excluded by endosonography via endoscopy in case of recurrent upper gastrointestinal bleeding. Laparoscopic splenectomy provides adequate treatment in preventing any recurrent bleeding, if gastric arterial collaterals are caused by splenic artery thrombosis.

Intra-individual comparison of different contrast media concentrations (300 mg, 370 mg and 400 mg iodine) in MDCT.

OBJECTIVE: To compare intra-individual contrast enhancement in multi-detector-row computed tomography (MDCT) using contrast media (CM) containing 300, 370 and 400 mg iodine per ml (mgI/ml). METHODS: Six pigs underwent repeated chest MDCT using three different CM (iopromide 300, iopromide 370, iomeprol 400). An identical iodine delivery (IDR) rate of 1.5 gI/s and a constant total iodine dose of 300 mg/kg body weight were used. Dynamic CT were acquired at the level of the pulmonary artery, and the ascending and descending aorta. After the time enhancement curves were computed, the pulmonary and aortic peak enhancement, time to peak and plateau time above 300 HU were calculated. RESULTS: Intra-individual peak contrast enhancement was significantly higher for the 300 mgI/ml contrast medium compared with the 370 and 400 mgI/ml media: pulmonary trunk 595 HU vs 516 HU (p = 0.0093) vs 472 HU (p = 0.0005), and aorta 505 HU vs 454 HU (p = 0.0008) vs 439 HU (p = 0.0001), respectively. Comparison of time to peaks showed no significant difference. Plateau times were significantly longer for the 300 mgI/ml than for the 370 and 400 mgI/ml CM at all anatomical sites. CONCLUSION: Given normalised IDR and total iodine burden, the use of CM with a standard concentration with 300 mg iodine/ml provides improved contrast enhancement compared with highly concentrated CM in the chest.

Semiautomated versus manual evaluation of liver metastases treated by radiofrequency ablation.

PURPOSE: To determine the accuracy of semiautomated volume and density measurements of liver metastases from colorectal and breast cancer before and after radiofrequency (RF) ablation compared with manual evaluation. MATERIALS AND METHODS: Twenty-five patients (mean age, 63.2 years +/- 10.7) with 50 known liver metastases from underlying primary breast (n = 15) or colorectal cancer (n = 35) underwent triphasic contrast-enhanced multidetector computed tomography (CT) to evaluate hepatic tumor load and localization before RF ablation and for postinterventional follow-up. Each lesion was quantified in terms of volume and CT value (in HU) with a semiautomated software tool and manually by an experienced radiologist before and 4 months after RF ablation. RESULTS: Before RF ablation, all 50 liver metastases, and after ablation, 49 of 50 ablation zones (98%), were correctly evaluated by the software. Mean lesion volumes before and after the intervention were 5.5 cm(3) and 22.4 cm(3), respectively. Corresponding concordance correlation coefficients between measurement techniques were 0.98 and 0.99, respectively, for volume; and 0.90 and 0.76, respectively, for CT value. CONCLUSIONS: Compared with manual measurements, semiautomated volumetric assessment of liver metastases before and after RF ablation demonstrated a high degree of correlation. Agreement of attenuation was slightly worse, particularly when assessing the postinterventional multidetector CT examination, probably because of the different regions of interest used for manual and semiautomated assessment of CT values.