Liver SPECT Research Articles

Prior ablation and progression of disease correlate with higher tumor-to-normal liver 99mTc-MAA uptake ratio in hepatocellular carcinoma.

Factors affecting tumor-to-normal tissue ratio (T:N) have implications for patient selection, dosimetry, and outcomes when considering radioembolization for HCC. This study sought to evaluate patient, disease specific, and technical parameters that predict T:N as measured on planning pre-90Y radioembolization 99mTc-MAA scintigraphy for hepatocellular carcinoma (HCC). 99mTc-MAA hepatic angiography procedures with SPECT/CT over a 4-year period were reviewed. Data recorded included patient demographics, details of underlying liver disease, tumor size, history of prior treatments for HCC and technical parameters from angiography. Anatomic-based segmentation was performed in 93 cases for measurement of tumor and perfused liver volumes and SPECT counts. T:N were calculated and correlated with collected variables. Mean calculated T:N was 2.52. History of prior ablation was significantly correlated with higher T:N (mean 3.39 vs 2.24, p = 0.003). Cases in which mapping was being performed for treatment of disease progression was significantly correlated with higher T:N (mean 3.35 vs 2.14, p = 0.001). Larger tumor size trended toward lower T:N (p = 0.052). Patients with history of ablation and those undergoing treatment for disease progression have higher T:N and, therefore, could be considered for radioembolization preferentially over alternative treatments.

Liver Function Preservation and Outcome after SBRT with Functional Treatment Planning in Patients with HCC and Advanced Hepatic Cirrhosis: From Nuclear Medicine to MRI-Based Functional Treatment Planning Platform

<h3>Purpose/Objective(s)</h3> To evaluate treatment outcomes of ablative SBRT with SPECT/CT and MRI-guided functional treatment planning for localized HCC in patients with Child-Pugh B (CP-B) cirrhosis. <h3>Materials/Methods</h3> Liver SPECT with ^99mTc-sulfur colloid was co-registered to 3D-CT for identification and avoidance of functional hepatic parenchyma during SBRT in patients with advanced cirrhosis. Likewise, MRI scanner of the Unity® MR-Linac with super-paramagnetic iron oxide nanoparticle (SPION) agent Feraheme® as an alternative contrast was used for treatment planning with visualization of tumor and functional liver parenchyma during SBRT. Functional liver volumes (FLV) obtained from CT-SPECT or SPION-MRI were compared to anatomical liver volumes, as were dosimetric parameters when radiation dose constraints were adapted exclusively to FLV. Hepatic function, toxicity, and radiographic response were documented every 3-4 months following SBRT. <h3>Results</h3> With a median follow-up of 25 months, 44 patients (59 lesions treated) with CP-B cirrhosis received ablative SBRT to a median dose of 48 Gy (3–5 fractions). An automated contouring algorithm was generated for delineation and guided avoidance of best functional hepatic parenchyma on SPION-MRI. Prolonged SPION-contrast retention within hepatic parenchyma allowed per fraction treatment plan adaptation with SPION-enhanced MR imaging of tumor throughout the treatment course. FLV loss (509 cc or 41.3%, p<0.001) was observed in all patients, while the functional and anatomical liver volumes matched well in a control group of non-cirrhotic/non-HCC patients. Mean dose to residual FLV was maintained well below the liver threshold tolerance to radiation in all patients. Thirty-six transplant eligible patients received SBRT as a bridging treatment and 26 patients (60% of the cohort) were listed for liver transplant after completion of SBRT. Twenty-two patients successfully completed orthotopic liver transplant (OLT) with a median time to transplant of 6.1 months. Eight of 10 patients with intrahepatic progression received additional SBRT during follow-up and four of them completed transplant. With 95% in-field local control rate, overall, 2-year survival was 63% (90% after the OLT) with no incidence of RILD or CP class migration observed at 6+ months post SBRT. <h3>Conclusion</h3> SBRT with functional treatment planning on SPEC/CT allows identification and guided avoidance of residual functionally active hepatic parenchyma in patients with advanced hepatic cirrhosis. SPION-enhanced MRI provides consistent visibility of liver tumors and functional hepatic parenchyma on the day of treatment planning and throughout the online MR-guided SBRT. We report high local control and low toxicity leading to satisfactory pre- and post-liver transplant outcomes. Prospective clinical trial investigating MRI-SPION adaptive planning on the 1.5T Elekta Unity® MR-Linac is ongoing in our institution.

Estimation of post-therapeutic liver reserve capacity using 99mTc-GSA scintigraphy prior to carbon-ion radiotherapy for liver tumors.

There is currently no established imaging method for assessing liver reserve capacity prior to carbon-ion radiotherapy (CIRT) for liver tumors. In order to perform safe CIRT, it is essential to estimate the post-therapeutic residual reserve capacity of the liver. To evaluate the ability of pre-treatment 99mTc-galactosyl human serum albumin (99mTc-GSA) scintigraphy to accurately estimate the residual liver reserve capacity in patients treated with CIRT for liver tumors. This retrospective study evaluated patients who were performed CIRT for liver tumors between December 2018 and September 2020 and underwent 99mTc-GSA scintigraphy before and 3 months after CIRT, and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI within 1 month before CIRT were evaluated. The maximal removal rate of 99mTc-GSA (GSA-Rmax) was analyzed for the evaluation of pre-treatment liver reserve capacity. Then, the GSA-Rmax of the estimated residual liver (GSA-RL) was calculated using liver SPECT images fused with the Gd-EOB-DTPA-enhanced MRI. GSA-RL before CIRT and GSA-Rmax at 3 months after CIRT were compared using non-parametric Wilcoxon signed-rank test and linear regression analysis. Overall, 50 patients were included (mean age ± standard deviation, 73 years ± 11; range, 29-89 years, 35 men). The median GSA-RL was 0.393 [range, 0.057-0.729] mg/min, and the median GSA-Rmax after CIRT was 0.369 [range, 0.037-0.780] mg/min (P = .40). The linear regression equation representing the relationship between the GSA-RL and GSA-Rmax after CIRT was y = 0.05 + 0.84x (R2 = 0.67, P < .0001). There was a linear relationship between the estimated and actual post-treatment values for all patients, as well as in the group with impaired liver reserve capacity (y = - 0.02 + 1.09x (R2 = 0.62, P = .0005)). 99mTc-GSA scintigraphy has potential clinical utility for estimating the residual liver reserve capacity in patients undergoing carbon-ion radiotherapy for liver tumors. UMIN000038328, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000043545 .

Stereotactic body radiotherapy (SBRT) with functional treatment planning in patients with hepatocellular carcinoma (HCC) and advanced hepatic cirrhosis: Survival outcomes and toxicity.

460 Background: To evaluate outcomes and dosimetric parameters of ablative stereotactic body radiotherapy (SBRT) with functional treatment planning for localized hepatocellular carcinoma (HCC) in patients with Child-Pugh B (CP-B) hepatic cirrhosis. Methods: Liver SPECT with 99mTc-sulfur colloid was co-registered to 3D-CT for identification and avoidance of functional hepatic parenchyma during SBRT in patients with advanced cirrhosis. Functional liver volumes (FLV-SPECT) were compared to anatomical liver volumes, as were dosimetric parameters when radiation dose constraints were adapted exclusively to FLV-SPECT. Hepatic function, toxicity, and radiographic response were documented every 4–6 months following SBRT. Results: With a median follow-up of 25 months 37 patients (48 lesions treated) with CP-B cirrhosis received SBRT to a median dose 48 Gy (4–5 fractions). FLV-SPECT volume loss (509 cc or 41.3%, p &lt; 0.001) was observed in all patients, while the functional and anatomical liver volumes matched well in a control group of non-cirrhotic/non-HCC patients. While tumors received ablative irradiation, mean dose to FLV-SPECT was maintained at 1.3 – 16 Gy (median 9.17 Gy), well below the liver threshold tolerance to radiation. Seventeen patients successfully completed liver transplant at a median time to transplant of 6.5 months. The dropout rate from the transplant list was 9 % with intrahepatic progression outside treated tumors. Eight of 10 patients with intrahepatic progression received additional SBRT during follow-up. Overall 2-year survival rate was 65% with no incidence of RILD or CP class migration from B to C was observed at 6+ months post SBRT. Two patients completed liver SBRT on a hybrid linear accelerator combined with MRI scanner (Unity MR-Linac, Elekta) utilizing Super-Paramagnetic Iron Oxide (SPIO) nanoparticle agent as an alternative contrast media for functionally active liver parenchyma. Prolonged SPIO-contrast retention also allowed per fraction treatment plan adaptation and enhanced tumor imaging. Conclusions: SBRT planning with 99mTc sulfur colloid SPECT allows identification and conformal avoidance of residual functionally active hepatic parenchyma in patients with CP-B cirrhosis. We report high local control and low toxicity leading to satisfactory pre- and post-liver transplant outcomes. Prospective clinical trial investigating MRI-SPIO functional treatment planning for liver SBRT is ongoing at our institution.

Optimization of newly developed and lead shields thicknesses for protecting taxi drivers from 99mTc injected patients

Presently, public members are exposed to sources of ionizing radiation, and health risks due to radiation exposures should be a concern. This study aims to calculate the whole-body cumulative radiation exposure of taxi drivers. Also, this study will provide the effect of using a simple lead shield and three types of glass shield AVT6, TZN-D, and SLGC-E5, by calculating the effective annual dose of the taxi drivers that work in medical centers. Two MIRD phantoms as a driver and patient, a sample body of a taxi, pure lead, and glass sheets as a shield, were simulated using the MCNP code. We assumed that the patients had undergone the brain, liver, and kidney SPECT imaging by injecting 99mTC-HMPAO, 99mTC-sulfur colloid, and 99mTC-DMSA with the activity of 740MBq, 185MBq, and 333MBq, respectively. These shields are simulated on two sides of the driver, in the back and right side. The annual effective dose was calculated for 0–3.5 g/cm2 area densities. It was observed that the 0.45, 1.09, 1.28, and 2.11 g/cm2 of Pb, TZN-D, AVT6, and SLGC-E5 respectively decrease the effective dose below the allowed limit. According to the results, using the lead shield, the effective dose was reduced by a factor up to 7.25 times. It is recommended that taxi drivers wear a 0.4 mm lead shield or its equivalent when they have Tc-99 m injected patients.

Absorbed doses of the taxi drivers in the vicinity of the patients that were injected for SPECT imaging: a Monte Carlo study

Nuclear medicine is a branch of medical science that uses radionuclides for diagnosing and treatment of diseases. In this paper, the dose of the different organs and annual effective dose of a taxi driver were calculated in a vicinity of a patient that was injected for the brain, kidney, and liver SPECT by using Monte Carlo method. Two MIRD phantoms were simulated as a driver and patient, including the simple body of a taxi in MCNPX2.4 code. The radioactivity distributions were obtained from ICRP reports and sources were defined according to them. The patients that have undergone the brain, kidney and liver SPECT with the injection of different activities of the 99mTC radioisotope were included in this study. The injected activities were 740 MBq, 185 MBq, and 333 MBq for the brain, kidney, and liver SPECT respectively. Annual effective doses were calculated for one 99mTC injected patient per working day with an assumption of 30 min ride duration. The maximum annual effective doses of the taxi driver were 2.31, 0.54, and 1.21 $$\upmu \mathrm{S}\mathrm{v}$$ in the vicinity of the patients that were injected for brain, kidney, and liver SPECT respectively. The maximum annual effective dose of the taxi driver is larger than the ICRP recommended data up to 2.3 times. We recommend that to reduce dose, the patient should sit in “position 2”, farthest back seat with respect to the driver, and the driver’s seat could have some shielding place around it.

Fast quantitative reconstruction with focusing collimators for liver SPECT

BackgroundGeneration of a SPECT scan during procedure may aid in the optimization of treatments as liver radioembolization by offering image-guided dosimetry. This, however, requires both shortened acquisition times and fast quantitative reconstruction. Focusing collimators increase sensitivity and thus may speed up imaging. Monte Carlo-based iterative reconstruction has shown to provide quantitative results for parallel hole collimators but may be slow. The purpose of this work is to develop fast Monte Carlo-based reconstruction for focusing collimators and to evaluate the impact of reconstruction and collimator choice on quantitative accuracy of liver dosimetry by means of simulations.ResultsThe developed fast Monte Carlo simulator was found to accurately generate projections compared to a full Monte Carlo simulation, providing projections in several seconds instead of several days. Monte Carlo-based scatter correction was superior to other scatter correction methods in describing recovered activity and reached similar noise levels as dual-energy window scatter correction. Although truncation artifacts were present in the cone beam collimator (50 cm), the region inside the field of view (FOV) could be reconstructed without loss of accuracy. Provided the object to image is inside the FOV, the focusing collimator with 50 cm focal distance could retrieve the same noise levels as a parallel hole collimator in 68% of the total scanning time, the multifocal collimator in 73% of the time, and the 100-cm focal distance collimator in 84% of the time.ConclusionFocusing collimators combined with Monte Carlo-based reconstruction have the ability to enable quantitative imaging of the FOV in a significantly shorter timeframe. The proposed approach to the forward projector will additionally make it possible to reconstruct within minutes. These are crucial steps in moving toward real-time dosimetry during interventions.

Fast technetium-99m liver SPECT for evaluation of the pretreatment procedure for radioembolization dosimetry.

PurposeThe efficiency of radioembolization procedures could be greatly enhanced if results of the 99mTc‐MAA pretreatment procedure were immediately available in the interventional suite, enabling 1‐day procedures as a result of direct estimation of the hepatic radiation dose and lung shunt fraction. This would, however, require a relatively fast, but still quantitative, SPECT procedure, which might be achieved with acquisition protocols using nonuniform durations of the projection images.Methods SPECT liver images of the 150‐MBq 99mTc‐MAA pretreatment procedure were simulated for eight different lesion locations and two different lesion sizes using the digital XCAT phantom for both single‐ and dual‐head scanning geometries with respective total acquisition times of 1, 2, 5, 10, and 30 min. Three nonuniform projection‐time acquisition protocols (“half‐circle SPECT (HCS),” “nonuniform SPECT (NUS) I,” and “NUS II”) for fast quantitative SPECT of the liver were designed and compared with the standard uniform projection‐time protocol. Images were evaluated in terms of contrast‐to‐noise ratio (CNR), activity recovery coefficient (ARC), tumor/non‐tumor (T/N) activity concentration ratio, and lung shunt fraction (LSF) estimation. In addition, image quality was verified with a physical phantom experiment, reconstructed with both clinical and Monte Carlo‐based reconstruction software.ResultsSimulations showed no substantial change in image quality and dosimetry by usage of a nonuniform projection‐time acquisition protocol. Upon shortening acquisition times, CNR dropped, but ARC, T/N ratio, and LSF estimates were stable across all simulated acquisition times. Results of the physical phantom were in agreement with those of the simulations.ConclusionBoth uniform and nonuniform projection‐time acquisition liver SPECT protocols yield accurate dosimetric metrics for radioembolization treatment planning in the interventional suite within 10 min, without compromising image quality. Consequently, fast quantitative SPECT of the liver in the interventional suite is feasible.

I163] Dosimetric planning of liver radioembolization with 90Y microspheres: Methodological problems and clinical achievements

Purpose The apparent simplicity of individualized dosimetry in radioembolization with 90Y microspheres has pushed many centres to collect data. As a result, dosimetric papers and software advances obtained in 10 years are much more than those produced in 70 years of metabolic therapy with other radiopharmaceuticals. Aim of this lecture is to enlighten the limits of the present planning methodology and to remark the importance of the clinical results obtained. Methods Dosimetric treatment planning is based on 99mTc albumin macroaggregate (MAA) SPECT/CT. Scatter correction is mandatory. The patient relative calibration method makes a correspondence between total 99mTc SPECT counts and the intended 90Y activity, using each patient as a calibration phantom for himself. Local energy deposition method more accurately represents the true activity distribution than convolution methods, but not in lung, where convolution is necessary. Breathing motion is a problem both in liver SPECT and CT. In hepatocarcinoma (HCC), segmentation of large lesions showing a necrotic core raise the problem of SPECT versus CT based segmentation. Infiltrative lesions can be evidenced with MRI only, but the two compartment model cannot be applied. Voxel dosimetry is limited by SPECT noise, which acts as intrinsic uncertainty principle. The heaviest source of uncertainty is the discrepancy between MAA and actual 90Y microsphere biodistribution. Results Despite the above mentioned limits, dose response correlations have been reported by almost all researchers, with both kind of microspheres and for several kind of disease (HCC, colorectal metastases). Dose toxicity correlation has been less studied but it has been reported. The most striking results, never reported previously for any other therapeutic agents, is that at a multivariate analysis, lesion absorbed dose is the only variable associated with overall survival. Conclusions While limitations of the treatment planning methodology result in a poor prognostic value on some individual patient, we have strong indications of improvements of clinical outcome in terms of general parameters of the treated population (response and toxicity rate, progression free and overall survival).

Liver stereotactic radiotherapy (SRT) with functional treatment planning for patients with intermediate stage hepatocellular carcinoma (HCC)

The objective of this study was to analyze hepatic failure progression and survival in patients with Barcelona Clinic Liver Cancer (BCLC) A3-B hepatocellular carcinoma (HCC) after stereotactic radiotherapy (SRT) with functional treatment planning. Liver SPECT was co-registered to 4DCT for avoidance of functional liver during SRT planning. Liver dose constraints/fractionation was based on functional liver volume. Concurrent capecitabine was administered for fraction size ≤ 4 Gy. Hepatic function, toxicity, and radiographic response were documented q4–6 months following radiotherapy. Twenty-two patients (14 Child-Pugh A, 8 Child-Pugh B Cirrhosis) with 39 lesions were analyzed. Fourteen patients received SBRT (mean dose 44.7 Gy, 5–6 fractions). Eight patients received SRT and concurrent capecitabine (mean dose 40.7 Gy, 14–18 fractions). Mean follow-up was 20 months. Nine patients developed grade ≤ 2 transient elevation of liver enzymes. At 24 months, Child-Pugh class was stable in 59% patients and MELD progression free survival was 76%. No RILD or accelerated hepatic failure was observed. In-field local control was 97.4% and overall survival was 59% at 2 years. Liver SRT with functional treatment planning is safe in intermediate hepatocellular carcinoma. Liver failure is not hastened despite the inclusion of 36% Child-Pugh B patients.

Preparation and biological evaluation of 99m Tc-timonacic acid as a new complex for hepatobiliary imaging

Timonacic acid (TCA) was successfully labeled with 99mTc. The influence exerted on the reaction by the substrate and reducing agent concentrations, pH of the reaction mixture, and reaction time was examined, and in vitro stability of 99mTc-TCA was evaluated. The maximum labeling yield was 98.5 ± 0.6%. The complex was stable throughout the working period (6 h). A study of in-vivo biodistribution in mice showed that the maximum uptake of 99mTc-TCA in the liver was 22.3 ± 0.3% of the injected activity per gram of the tissue or organ (% ID/g) at 30 min post injection. The clearance from the mice appeared to proceed via the circulation mainly through the kidneys and urine (approximately 56% of the injected dose at 1 h after injection). The liver uptake of 99mTc-TCA is higher than that of 99mTc-UDCA (ursodeoxycholic acid); therefore, 99mTc-TCA shows more promise for liver SPECT.

Kit formulated asialoglycoprotein receptor targeting tracer based on copolymer for liver SPECT imaging.

Specific targeting of galactose-carrying molecule to ASGP-R in normal hepatocytes has been demonstrated before. In this study, galactosyl polystyrene was synthesized from controllable ratio of functional monomers and radio-labelled with (99m)Tc by formulated kit for SPECT imaging of hepatic function. p(VLA-co-VNI)(46:54) was synthesized by free-radical copolymerization initiated by AIBN, purified by dialysis, lyophilized to kit with Tricine and TPPTS as co-ligands for (99m)Tc labeling. Radiotracer (99m)Tc-p(VLA-co-VNI)(46:54)(Tricine)(TPPTS) was prepared and evaluated by in vitro stability, in vivo metabolism, ex vivo biodistribution and microSPECT/CT imaging in normal KM mice. MicroSPECT/CT and microMRI imaging were also performed in C57BL/b6 mice with xenograft hepatic carcinoma for hepatic function evaluation. (99m)Tc-p(VLA-co-VNI)(46:54)(Tricine)(TPPTS) was obtained in high radio chemical purity (RCP) (>99%) by using instant kit without further purification and excellent in vitro and in vivo stability. The result of biodistribution showed that liver had high uptake (90.49±10.68 ID%/g) at 30 min after injection and was blocked significantly by cold copolymer. MicroSPECT imaging in normal KM mice at 1h and 4h after injection showed good liver retention and targeting properties. Significant defect of activity was observed in the tumor site which was confirmed by MRI imaging. (99m)Tc-p(VLA-co-VNI)(46:54)(Tricine)(TPPTS) with lower ratio of targeting moiety has no observable effect on the specific binding affinity and liver uptake. This makes it possible to introduce more imaging units for multi-modality imaging. Furthermore, the instant kit preparation of (99m)Tc-labeling provides great potential for the evaluation of hepatocyte function in clinical application.

Predictive value of Tc-99m galactosyl human serum albumin liver SPECT on the assessment of functional recovery after partial hepatectomy: a comparison with CT volumetry

Predicting liver functional reserve is important before partial hepatectomy. However, it is difficult to predict using morphologic imaging modalities, such as CT and MRI. In this study, we assess the usefulness of galactosyl human serum albumin (GSA) scintigraphy in predicting liver function recovery. We performed 99mTc-GSA scintigraphy before operation in 56 patients. Each patient was administered 185 MBq of 99mTc-GSA by intravenous injection. Serial images were taken immediately after the administration for 40 min. SPECT images were obtained to make a functional map. We calculated the functioning parameter residual GSA-Rmax (GSA-RL) using analysis software developed by Dr.N. Shuke. In addition, we compared GSA-RL with the morphological parameter residual liver volume (RLV-CT) calculated by conventional CT and serum albumin (Alb) or cholinesterase (ChE). We analyzed the correlation between imaging parameters and the postoperative recovery periods of serum albumin (r-Alb) and cholinesterase (r-ChE) and the values at 1 and 3 months for serum albumin (1M-Alb, 3M-Alb) and cholinesterase (1M-ChE, 3M-ChE). We found significant correlations between GSARL and r-Alb, r-ChE, 1M-Alb, 3M-Alb, 1M-ChE and 3M-ChE, but not between RLV-CT and the same parameters. The GSA-RL calculated by 99mTc GSASPECT was a useful parameter for predicting postoperative liver function recovery that should be implemented before partial hepatectomy.

A study on attenuation correction using Tc-99m external TCT source in Tc-99m GSA liver SPECT

In attenuation correction of ECT images by transmission CT (TCT) with an external 99mTc gamma-ray source, simultaneous TCT/ECT data acquisition is difficult, when the same radionuclide such as 99mTc-tetrofosmin or 99mTc-GSA is used as the tracer. In this case, TCT is usually acquired before administration of the tracer, and ECT is acquired separately after the tracer injection. However, misregistration may occur between the TCT and ECT images, and the repetition of examinations add to the mental and physical stress of the patients. In this study, to eliminate this problem, we evaluated whether attenuation correction of ECT images can be achieved by acquiring TCT and ECT simultaneously, then acquiring ECT alone, and preparing an attenuation map by subtracting the latter from the former using 99mTc-GSA liver ECT. The ECT system used was a three-head gamma camera equipped with one cardiac fan beam collimator and two parallel beam collimators. External gamma-ray source for TCT of 99mTc was 740 MBq, and ECT of 99mTc-GSA was 185 MBq. First, pure TCT data were acquired for the original TCT-map, then, ECT/TCT data were acquired for the subtracted TCT-map, and finally, pure ECT data were acquired. The subtracted attenuation map was produced by subtracting the pure ECT image from the TCT/ECT image, and attenuation correction of the ECT image was done using both this subtracted TCT map and attenuation map from pure TCT. These two attenuation corrected images and non-corrected images were compared. Hot rods phantom, a liver phantom with a defect, and 10 patients were evaluated. Attenuation corrected ECT values using the subtraction attenuation map showed an error of about 5% underestimation compared with ECT values of the images corrected by original attenuation map at the defect in the liver phantom. A good correlation of y = 22.65 + 1.06x, r = 0.958 was observed also in clinical evaluation. By means of the method proposed in this study, it is possible to perform simultaneous TCT/ECT data acquisition for attenuation correction using Tc-99m external source in Tc-99m GSA liver SPECT. Moreover, it is thought that this method decreases the mental and physical stress of the patients.

Nodular regenerative hyperplasia of the liver: SPECT evaluation with Tc-99m stannous colloid and Tc-99m neoglycoalbumin

The authors describe a case of nodular regenerative hyperplasia of the liver and its findings on liver SPECT with Tc-99m radiocolloid and Tc-99m neoglycoalbumin. A 22-year-old woman with systemic lupus erythematosus was hospitalized for intractable thrombocytopenia. A diagnostic work-up including CT revealed multiple liver nodules and portal hypertension with splenomegaly, suggesting hypersplenism as a cause of the thrombocytopenia. Liver SPECT with Kupffer cell–oriented Tc-99m stannous colloid and hepatocyte-oriented Tc-99m neoglycoalbumin showed increased uptake in the liver nodules, indicating the presence of Kupffer cells and hepatocytes. The patient underwent splenectomy and wedge liver biopsy. Pathologic analysis of the liver specimen revealed many hyperplastic nodules and sinusoidal congestion without cirrhosis. Based on these histopathologic features, the diagnosis of nodular regenerative hyperplasia of the liver was made. FIGURE 1Fig. 1: (A) CT shows no appreciable liver nodules. Contrast-enhanced liver nodules are demonstrated in (B) the arterial-dominant and (C) the portal-dominant phases of the sequential contrast-enhanced liver CT. (D) CT during arterioportography shows many contrast-enhanced liver nodules. The largest nodule is seen in the left medial segment. These findings indicate that these nodules had arterial and portal blood supplies. Although most nodules were described to be hypodense as seen on plain CT (1), all nodules in this case are isodense.FIGURE 2Fig. 2: Planar (A) anterior and (B) posterior images with Tc-99m stannous colloid show a heterogeneous distribution and focal increased uptake. Splenomegaly with increased splenic uptake is also noted. According to previous reports, patchy liver uptake, focal photopenic areas with focal patchy uptake within the nodule, and photon-deficient defects were described as the findings of nodular regenerative hyperplasia on radiocolloid liver scintigraphy (2,3).FIGURE 3Fig. 3: Transaxial SPECT images with Tc-99m stannous colloid show focal increased uptake in the liver. The obvious focal uptake (arrow) corresponds to the nodule seen in the left medial segment on the contrast-enhanced CT. Because Smith (3) has raised the possibility of this finding, the focal increased uptake could be related to hyperplasia of Kupffer cells and to possible heterogeneous blood flow (4).FIGURE 4Fig. 4: Transaxial SPECT images with Tc-99m neoglycoalbumin, which is a specific ligand for the asialoglycoprotein (galactose-terminated glycoprotein) receptor on the surface of the hepatocyte (5), show focal increased uptake in the same areas as in the Tc-99m stannous colloid SPECT. The obvious focal uptake (arrow) corresponds to the nodule seen in the left medial segment on Tc-99m stannous colloid SPECT. Because the presence of both Kupffer cells and virtually normal hepatocytes in the nodules were shown, these SPECT findings suggested that the hepatic nodules could have a benign character, although it was difficult to recognize small nodules and confluent nodules on the SPECT images. Multiple benign liver nodules associated with systemic lupus erythematosus and portal hypertension raised the possibility of nodular regenerative hyperplasia of the liver. The patient underwent splenectomy to treat the thrombocytopenia, and a wedge liver biopsy was performed. Histopathologic examination of the liver specimen revealed many noncirrhotic hyperplastic liver nodules without perinodular fibrosis, the sizes of which ranged from 1 mm to 2 cm in diameter. Microscopic examination showed that the the nodules consisted of hyperplastic normal hepatocytes. Perivascular fibrosis was also seen. However, fibrous septa or infiltration of the inflammatory cells, which were suggestive of cirrhosis, were not seen. The diagnosis of nodular regenerative hyperplasia of the liver was made based on these histopathologic findings (4).

Normal vasculature in Tc-99m RBC labeled liver SPECT with corresponding CT: all is not tumor that is hot.

Hepatic tumors are often observed as hot spots on Tc-99m labeled RBC SPECT imaging. Because normal blood vessels also show increased activity, it would be important to know their location and appearance. The authors show contrast enhanced CT images with corresponding SPECT images of a patient who does not have a hepatic tumor. Additional SPECT images with different reconstruction processing are also shown to emphasize the importance of optimal processing.

Scintigraphic Study of Propylthiouracil Induced Submassive Hepatic Necrosis

Drug induced hepatitis is a rare complication of thiourea antithyroid drugs. In some patients, the hepatotoxicity may be severe and lead to submassive hepatic necrosis (SHN). Submassive hepatic necrosis is a potentially fatal complication which is usually recognized on the liver biopsy and histological examination or autopsy. In the case presented here, SHN was identified on Tc-99m SC liver images. Sharply defined intrahepatic photopenic abnormalities without significant colloid shift were noted. SPECT images were most remarkable and exhibited extensive liver necrosis. Resolution of hepatic abnormalities correlated with clinical and biochemical resolution of SHN. In patients with propylthiouracil hepatotoxicity, serial liver SPECT images with Tc-99m SC appear helpful for the diagnosis and follow up of SHN and, in an appropriate clinical context, may obviate the need for liver biopsy.

Cavernous Hemangiomas of the Liver

To determine if the sonographic appearance of cavernous hemangiomas of the liver correlated with their detectability on Tc-99m labeled red blood cell (RBC) SPECT scintigraphy, studies of 30 cavernous hemangiomas, 14 with typical and 16 with atypical sonographic appearance, were retrospectively reviewed. The 14 typical hemangiomas had uniform hyperechoic sonographic appearance, and ranged in size from 0.8-3.9 cm (mean 2.0 cm). The 16 atypical hemangiomas ranged in size from 1.0-9.0 cm (mean 3.4 cm) and sonographic appearance was hypoechoic (n = 9), echogenic (with hypoechoic or cystic center [n = 3] or with irregular margins or shape [n = 2]); or heterogeneous (n = 2). Nine of 14 (64%) typical cavernous hemangiomas were identified on SPECT, compared with 15 of 16 (94%) atypical cavernous hemangiomas (P = 0.07). All 18 lesions > or = 2 cm (6 typical, 12 atypical) were identified on SPECT. Sensitivity of SPECT for hemangiomas of smaller than 2 cm was 38% (3 of 8) for those with typical and 75% (3 of 4) for those with atypical sonographic appearance. Four of the five typical hemangiomas not seen on SPECT were < or = 1 cm in at least one dimension. Detection of cavernous hemangiomas on RBC liver SPECT is primarily dependent on lesion size, with the influence of the sonographic appearance of these lesions mostly associated with the smaller size of those with typical characteristics.

Bone marrow scintigraphy in lung carcinomas using nanosized colloids: when is it useful and how useful is it?

Bone marrow scintigrams (MS) combined with single photon emission computed tomographic investigation of the liver (liver SPECT) were obtained using 99Tcm-labelled human serum albumin nanosized colloids in 52 patients with histologically proven lung carcinomas (adenocarcinomas = 17, squamous cell = 16, small cell = 14, large cell = 5, 31 generalized cases at the time of the first MS investigation among whom 13 patients had proven skeletal metastases). They were compared with conventional bone scintigrams (BS) as well as clinical, biological, radiological and follow-up data obtained for the same patients. In the present series, MS appeared as sensitive as BS in diagnosing skeletal metastases (77%) if all abnormal MS and BS presentations are considered as diagnostic, but more sensitive (77% versus 54%) if more restrictive analytical criteria are applied. The two investigations yielded the same specificities whatever the analytical criteria applied. These preliminary conclusions have, however, to be confirmed on larger populations than the present series. The most striking differences between BS and MS were observed in the case of small-cell lung carcinomas, with more lesions detected by MS than by BS. Liver SPECT also made it possible to diagnose seven and to suspect one out of the ten situations of hepatic metastases. The combination of liver spect and MS in the framework of a single injection of 99Tcm-labelled nanosized colloids thus allowed us to diagnose 80% of the patients with osseous and/or hepatic metastasis or 40% of all generalized cases.

Is SPECT of the spleen worthwhile in the evaluation of liver disease severity?

SPECT of the spleen has been performed with 99Tcm-sulphur colloid in 53 patients, and SPECT of the liver has been performed in 57 patients. All patients had histologically proven liver disease and were classified by the degree of severity, Group A-severe, Group B-moderate, Group C-mild. The patients were further classified as cirrhotic and non-cirrhotic. Eight controls were also studied. There is positive though poor correlation between splenic volume and uptake (r2 = 0.55). Splenic volume and uptake are significantly different in Group A patients compared with all other groups (p less than 0.001). They are also significantly different in cirrhotics versus non-cirrhotics and cirrhotics versus controls (p less than 0.001). Splenic SPECT was unhelpful in distinguishing between moderate and mild liver disease. SPECT of the spleen is a time consuming technique but a useful adjunct to liver SPECT in patients with portal hypertension.